EP1042369A1 - Gel-free process for making functionalized anionically polymerized polymers - Google Patents

Abstract

The present invention relates to a process for making gel-free functionalized anionic polymers using multi-alkali metal initiators which comprises: anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, capping the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly associating chain ends are formed wherein a strongly associating gel is formed, and adding a trialkyl aluminum compound to the gel. According to a further embodiment, the invention relates to a gel-free process for making functionalized anionic polymers using multi-alkali metal initiators which comprises: anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, adding a trialkylaluminum compound before or during polymerization or before or at the same time as the capping agent, and capping the polymer by adding to the polymer a capping agent which, in the absence of the trialkylaluminum compound, would react with the polymer chain ends to form strongly associating chain ends wherein a strongly associating gel would be formed. Further aspects of the invention relate to a process for making functionalised polymer from unfunctionalised polymer; to a process for making functionalised polymer from polymers that are functionalised with a different functionality; and to a process for hydrogenating the polymers prepared by the above processes.

Description

- 1 -

GEL-FREE PROCESS FOR MAKING FUNCTIONALIZED ANIONICALLY POLYMERIZED POLYMERS

Field of the Invention

This invention relates to a gel-free process for making functionalized polymers, primarily functionalized anionic polymers which are made using multi-lithium initiators. More particularly, this invention relates to a gel-free process for making polydiene diols. Background of the Invention

Functionalized anionically polymerized polymers of conjugated dienes and other monomers wherein the functionalization is terminal and/or internal are known. Particularly, U.S. Patent 5,393,843 describes polybutadiene polymers having terminal functional groups . One of the methods described for making such polymers involves anionic polymerization utilizing a dilithium initiator such as the adduct derived from the reaction cf m-diisopropenylbenzene with two equivalents of s_-BuLi . Monomer is added to the initiator in hydrocarbon solution and anionic living polymer chains grow outwardly from the ends of the dilithium initiator. These polymers are then capped to form functional end groups as described in U.S. Patent Nos. 4,417,029, 4,518,753, and 4,753,991. Of particular interest herein are terminal hydroxyl, carboxyl, sulfonate, and amine groups.

It has been observed that when the living polymer is reacted with the commonly available "capping" agents, the polymer in the hydrocarbon solution forms a gel . For purposes of this invention, a polymer gel is defined as a blend of a polymer and a hydrocarbon solvent that has a yield stress, that is, it will not flow unless it is acted on by at least some critical stress. A polymer gel - 2 -

as defined herein will require a significant application of force in order to initiate flow through an orifice. Of particular interest are gels that will not flow under the force of their own weight. The presence of gel that will not flow under the force of its own weight is readily detected by visual observation. This effect is observed by inverting a bottle containing the solution to see whether it flows to the bottom of the inverted flask. Gelled solutions will not readily flow to the bottom of the bottle.

The physical characteristics of these gels make them more difficult to handle in equipment which is designed for moving, mixing, or combining freely flowing liquids, i.e. materials without a significant yield stress. Pumps, reactors, heat exchangers, and other equipment that are normally used for making polymer solutions that can be characterized as viscous fluids are not typically suited to handling polymer gels. Thus, one would expect that processing equipment likely to be found at a manufacturing location that is designed to handle liquid polymer solutions, as defined above, would be ill suited to handling gels of this nature.

Without limiting the invention thereto, we offer the following theory as to why this gelation occurs. We believe that gelation results from the strong association of the "capped" polymer chain ends in the hydrocarbon solvents used, i.e., cyclohexanes/diethylether . In the case of an ethylene oxide capping agent, the polymer chain ends would be lithium alkoxides. In essence, these very polar lithium alkoxide sites interact strongly as they are formed and, in the nonpolar solvent, self- assemble into aggregates having multiple alkoxide centers. The association of alkoxide ends from multiple chains in a single aggregate provides a mechanism for network formation. Since the polymer chains each have two - 3 - alkoxide ends, having the ends anchored in different aggregates leads to elastic properties, creating a gel as defined herein.

A suggested mechanism for the formation of a strongly associating gel in the case of a polybutadiene diol is as follows :

Li — Li + Butadiene *» Li— CH₂PolymerCH₂— Li

CH2 PolymerCH2 — Li + 2 (ethyleneoxide ) -CH2 PolymerCH2 -

OLi LiO

Strongly Associating Gel

The dilithium initiation technology discussed above has advantages over other technologies used to make functionalized anionically polymerized polymers including polydiene diols and polyols. For instance, U.S. Patent 5,416,168 describes a process which utilizes a monolithium initiator which contains a protected functional center (Protected Functional Initiator) to make a polybutadiene mono-ol. The preparation of the initiator is complicated by the fact that the precursor to the initiator must contain the functional center that is desired in the final polymer and further that this center must be derivatized to make it inert to the chemistry used in making the C-Li bond in the initiator. Once the Protected functional initiator is prepared, it may be used to polymerize a suitable monomer such as butadiene. This process leaves the protected functional initiator on one end of the polymer chain and a living C-Li center on the other end of the chain. Optionally, the "living" end of the polymer chain may be reacted with a capping agent. If ethylene oxide is used as the capping agent, then a polybutadiene mono-ol is the product. These steps are then followed by a step of deprotecting the - 4 -

first functionalized polymer chain end. This chemistry frees the functionality on the other end of the polymer chain. Finally, the polymer product must be washed to remove the residue of the protecting agent and the residues of the reagent that were used to remove it.

It can be seen that a dilithium initiation process would be highly advantageous over such a protected functional initiator process in terms of elimination of process steps, cost, etc. The invention described herein is a process for producing terminally functional polymers using the di- or multi- organo alkali metal initiator method. This process for making terminally functional polymers avoids gel formation through the addition of "screening agents" which block or weaken the association of the polar functional moieties. Summary of the Invention

This invention relates to a gel-free process for making functionalized polymers. When multi-organo alkali metal initiators are used to make these polymers anionically, the process comprises anionically polymerizing at least one monomer with a multi-organo alkali metal initiator in a hydrocarbon solvent and then capping the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly associating chain ends are formed wherein a polymer gel is formed. The important characteristic of the capping agent herein is that it caps the living polymer and adds a functional group to the polymer chain end which will be strongly associating in the hydrocarbon solvent. The result of the association of the chain ends is that the solution will gel. The final step of the process is adding a trialkyl aluminum compound to the polymer gel which results in a freely flowing solution. In a second embodiment, the present invention relates to a process for making such polymers which comprises anionically polymerizing them as described and then capping the polymer by adding the above-described capping agent. An aluminum trialkyl is added before or during polymerization or before or with the capping agent (i.e., before a gel can form—prior to any reaction of the alkali metal with the gel-forming functionality) .

In the first embodiment, a gel is formed and then removed. In the second embodiment, the gel never is formed because of the presence of the trialkyl aluminum compound.

In a third embodiment, an unfunctionalized polymer is functionalized by lithiation and reaction with a capping agent of this invention, whereby a strongly associating gel is formed. A promoter such as triethylamine or tetramethylethylenediamine is necessary. In a fourth embodiment, an already functionalized polymer is reacted with R i_n (or an active Na or K compound) in order -to convert to a different functionality. In both embodiments, the gel can be broken by addition of trialkyl aluminum to the gel or prevented by addition thereof prior to the reaction of Li (or Na or K) with the gel-forming functionality. Detailed Description of the Invention

This invention relates to functionalized polymers and processes for avoiding gel formation, especially when such polymers are made by anionic polymerization using di- or multi-alkali metal, generally lithium, initiators. Sodium or potassium initiators can also be used. For instance, polymers which can be made according the present invention are those from any anionically polymerizable monomer, especially including terminal and internal functionalized polydiene polymers, including random and block copolymers with styrene, polyether - b - polymers, polyester polymers, polycarbonate polymers, polystyrene, acrylics, methacrylics, etc. Polystyrene polymers hereunder can be made in the same manner as the polydiene polymers and can be random or block copolymers with dienes .

In general, when solution anionic techniques are used, copolymers of conjugated diolefins, optionally with vinyl aromatic hydrocarbons, are prepared by contacting the monomer or monomers to be polymerized simultaneously or sequentially with an anionic polymerization initiator such as group IA metals, their alkyls, amides, silanolates, naphthalides, biphenyls or anthracenyl derivatives. It is preferred to use an organo alkali metal (such as lithium or sodium or potassium) compound in a suitable solvent at a temperature within the range from about -150 °C to about 150 °C, preferably at a temperature within the range from about -70 °C to about 100 °C. Particularly effective anionic polymerization initiators are organo lithium compounds having the • general formula:

RLi_n wherein R is an aliphatic, cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radical having from 1 to about 20 carbon atoms and n is an integer of 1 to 4. The organolithium initiators are preferred for polymerization at higher temperatures because of their increased stability at elevated temperatures.

Polyester polymers would be made by anionic polymerization of a cyclic ester such as a lactone. Caprolactone is frequently used. Polyether polymers would be made by anionic polymerization of a cyclic ether such as an epoxide . Ethylene oxide is frequently used. Polycarbonate polymers would be made by anionic polymerization of a cyclic carbonate. The cyclic carbonate of 1, 3-propanediol may be used. - 7

Functionalized polydiene polymers, especially terminally functionalized polybutadiene and polyisoprene polymers, optionally as copolymers, either random or block, with styrene, and their hydrogenated analogs are preferred for use herein. Especially preferred are polybutadiene diols. Such polymers are made as generally described above. One process for making these polymers is described in U.S. Patent No. 5,393,843 which is herein incorporated by reference.

Using a polydiene diol as an example, butadiene is anionically polymerized using a difunctional lithium initiator such as the sec-butyllithium adduct of diisopropenylbenzene as an example. The living chain ends are then capped with a capping agent such as described in U.S. Patents 4,417,029, 4,518,753, and 4,753,991, which are herein incorporated by reference. There are many multilithium initiators that can be used herein. The di- s-butyllithium adduct of m-diisopropenylbenzene is preferred because of the relatively low cost of the- reagents involved and the relative ease of preparation. Diphenylethylene, styrene, butadiene, and isoprene will also work well to form dilithium (or disodium) initiators by the reaction:

Li .Li

+ Li^u - (or Na°]

Styrene

Still another compound which will form a diinitiator with an organo alkali metal such as lithium and will work herein is the adduct derived from the reaction of 1,3- bis ( 1-phenylethenyl) benzene (DDPE) with two equivalents of a lithium alkyl:

CH₂R Li CH₂R Li RLi +

Related adducts which are also known to give effective dilithium initiators are derived from the 1,4-isomer of DDPE. In a similar way, it is known to make analogs of the DDPE species having alkyl substituents on the aromatic rings to enhance solubility of the lithium adducts. Related families of products which also make good dilithium initiators are derived from bis[4-(l- phenylethenyl) phenyl] ether, 4,4' -bis (1-phenylethenyl) - 1, 1' -biphenyl, and 2, 2 ' -bis [4- (1-phenylethenyl) - phenyl] propane (See L. H. Tung and G. Y. S. Lo, Macromolecules, 1994, 27, 1680-1684 (1994) and U.S. Patents 4,172,100, 4,196,154, 4,182,818, and 4,196,153 which are herein incorporated by reference) . Suitable lithium alkyls for making these dilithium initiators include the commercially available reagents (i.e., sec- butyl and n-butyl lithium) as well as anionic prepolymers of these reagents, polystyryl lithium, polybutadienyl lithium, polyisopreneyl lithium, and the like.

The polymerization is normally carried out at a temperature of 20 to 80 °C in a hydrocarbon solvent. Suitable solvents include straight and branched chain hydrocarbons such as pentane, hexane, octane and the like, as well as alkyl-substituted derivatives thereof; cycloaliphatic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and the like, as well as alkyl- substituted derivatives thereof; aromatic and alkyl- substituted derivatives thereof; aromatic and alkyl- substituted aromatic hydrocarbons such as benzene, naphthalene, toluene, xylene and the like; hydrogenated aromatic hydrocarbons such as tetralin, decalin and the like; linear and cyclic ethers such as dimethyl ether, methylethyl ether, diethyl ether, tetrahydrofuran and the like. The capping reaction is carried out in the same solution and usually at about the same temperature as the polymerization reaction, as a matter of convenience.

The general class of capping agents useful herein which form strongly associating chain ends and cause gelation are those which form alkali metal-0 or alkali metal-N (preferably, LiO and LiN) bonds. Specific capping agents which are highly useful herein include ethylene oxide and substituted ethylene oxide compounds, oxetane and substituted oxetane compounds, aldehydes, ketones, esters, anhydrides, carbon dioxide, sulfur trioxide, aminating agents which form lithium imides, especially imines, and suitable reactive amine compounds like 1, 5-diazabicyclohexane as described in United States Patent No. 4,816,520 which is herein incorporated by reference. At least 0.1 mole of capping agent per mole of polymer chain end is necessary to give sufficient functionalization for most applications. It is preferred that from 1 to 10 moles of the capping agent per mole of polymer chain end be used in the capping of the polymer although the upper limit is only a practical one determined by cost benefit.

At this point in the process, the polymer forms a gel. A trialkyl aluminum compound is then added to this gel which then dissipates. The alternative process involves adding the trialkyl aluminum compound to the polymer mixture before the alkali metal reacts with the gel-forming functionality to form a gel. It may be added before, during, or after polymerization before the addition of the capping agent. In these cases, no polymer gel forms. If the trialkyl aluminum is added before or 10 -

during polymerization, then less than a molar ratio of Al:Li of 1:1 should be added because the polymerization will stop if the ratio reaches 1:1. In yet another alternative, the trialkyl aluminum compound is added at the same time as the capping reagent. It may be premixed with the capping agent or just added to the reactor at the same time as the capping reagent. In this process, no polymer gel forms. Using triethyl aluminum as an example, it is believed that the mechanism of these two processes, adding the trialkyl aluminum reagent either before or after capping, is as follows:

Li — CH2PolymerCH2 — Li+2 (ethyleneoxide) CH2PolymerCH2 —

OLi LiO^'

Strongly

Associating

Gel

2Et3Al 2Et3Al

Et Et

I ø I _Ω 2 (ethyleneoxide) -CH2PolymerCH2- Et — Al — CH2PolymerCH2 —Al— Et »-

⁰ _^ Et Et ,- 0

Et Et

Al

Li Li Θ / \ / \

Et Et Et Et

Aluminate Complex .Θ of Living Polymer L Ti^•© Li Gel-free Aluminate Complex of EO Capped Polymer Gel-free

As described above, gel is avoided or removed by addition of a trialkyl aluminum compound. It is important that the chain end retains activity for nucleophilic substitution reactions after the "ate" complex has formed. Even after the trialkyl aluminum reagent has been added and the "ate" complex has formed, the chain end is still capable of further reaction. The trialkyl aluminum compounds used in the present invention are those wherein - li¬

the alkyl groups contain from 1 to 10 carbon atoms. Preferred trialkyl aluminum compounds are triethyl aluminum, trimethyl aluminum, tri-n-propylaluminum, tri- n-butylaluminum, triisobutylaluminum, tri-n- hexylaluminum, and trioctyl aluminum because these reagents are readily available in commercial quantities. Triethylalu inum is most preferred as it is least expensive on a molar basis.

The molar ratio of the trialkyl aluminum compound to the polymer chain ends is generally at least 0.1:1, preferably 0.33:1 and most preferably 0.66:1 to 1:1 since this results in a freely flowing solution. If it is less than 0.1:1, then the level of reduction in gel is too low to give an observable reduction in either the shear stress or the viscosity of the solution. If the ratio is more that 1:1, then the cost goes up unnecessarily but the advantages are still achieved. It is advantageous to be able to use less aluminum for cost purposes.

This invention is also applicable in situations- wherein an existing polymer is to be functionalized or wherein it is desired to convert the functionality of an already functionalized polymer using one of the gel- forming capping agents described herein.

For example, it is known to functionalize hydrogenated styrene-butadiene-styrene (SBS) block copolymers by first lithiating them by reaction with RLi_n in the presence of a promoter such as triethylamine or tetramethylethylenediamine (TMEDA) as described in U.S. Patents Nos. 4,868,243 and 4,868,245 which are herein incorporated by reference. A number of reactive Li⁺ sites are formed in the styrene blocks. If these are reacted, for example, with CO2, strongly associated gel forms. It may be broken by addition of trialkylaluminum to the gel - 12 - or prevented by such addition prior to addition of the CO2 as described above.

Also, an existing polyol such as polybutadiene diol, for example, can be reacted in a hydrocarbon solution such as cyclohexane with KH to form the potassium alkoxide. Potassium alkoxides are known to rapidly polymerize ethylene oxide which would afford a route to a block copolymer having polyethylene oxide end blocks and a polybutadiene center block. At the start of such a synthesis, upon reaction of the polyol with the KH, a gel will form. Trialkylaluminum will break up the gel or prevent its formation as described above.

According to a further aspect the product of the process of the invention is further subjected to a hydrogenation treatment.

Hydrogenation of polymers of conjugated dienes is typically accomplished with the use of nickel catalysts, as described in U.S. Patents Re. 27,145 and 4,970,254 and U.S. Patent Application Serial No. 07/785715 which are incorporated herein by reference. The preferred nickel catalyst is a mixture of nickel 2-ethylhexanoate and triethylaluminum. Hydrogenation may also be accomplished using the catalysts described in U.S. Patents 3,415,759 and 5,057,582, which are herein incorporated by reference. These catalysts are made by contacting one or more Group VIII metal carboxylates (CAS version, Group VIIIA in the previous IUPAC form, and Groups 8, 9 and 10 in the new notation) with one or more alkyl alumoxanes which were prepared by reaction of an aluminum alkyl with water. As described in the above patents, such catalysts produce excellent results in that they selectively hydrogenate ethylenic unsaturation to a high degree while basically unaffecting the aromatic unsaturation. The preferred Group VIII metals are nickel and cobalt. Other homogeneous hydrogenation catalysts can be used including those made with Ti, Ru, Rh, etc. Heterogeneous hydrogenation catalysts can also be used including those made with Pt, Pd, Ni, Co, etc.

It has been found, however, that in order to reach an acceptable degree of hydrogenation, that is an acceptable level of residual unsaturation, relatively high amounts of catalyst and/or a relatively long reaction time is required, especially when using of nickel 2-ethyl- hexanoate and triethyl mixture aluminium as hydrogenation catalyst.

It has now been found that a solution to this problem is to wash the polymer with aqueous acid prior to hydrogenation with a hydrogenation catalyst. Therefore, according to a further aspect, the present invention relates to a gel-free process for making hydrogenated functionalized anionic polymers using a multi-alkali metal initiator which comprises:

(a) anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, (b) capping the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly associating chain ends are formed wherein a polymer gel is formed,

(c) adding a trialkyl aluminum compound to the polymer gel whereby the gel dissipates,

(d) optionally terminating the polymerization by addition of a terminating agent,

(e) washing the polymer with aqueous acid , and

(f) hydrogenating the polymer with a hydrogenation catalyst.

According to an alternative embodiment, the present invention relates to a gel-free process for making hydrogenated functionalized anionic polymers using a multi-alkali metal initiator which comprises: (a) anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent,

(b) adding a trialkyl aluminum compound before or during polymerisation or before or at the same time as the capping agent, and,

(c) capping the polymer by adding to the polymer a capping agent which, in the absence of the trialkylaluminum compound, would react with the polymer chain ends to form strongly associating chain ends wherein a polymer gel would be formed,

(d) optionally terminating the polymerization by addition of a terminating agent,

(e) washing the polymer with aqueous acid, and

(f) hydrogenating the polymer with a hydrogenation catalyst.

Following functionalization, it is common practice to terminate the reaction by the addition of a terminating agent, preferably an alkanol, more preferably methanol. It is preferable to add a sufficient quantity of the terminating alcohol to provide one mole of the alcohol per mole of alkali metal, usually lithium, and three moles of the alcohol per mole of aluminum. Reaction with the alcohol results in alcoholysis of the alkylaluminum. In the case of triethylaluminum, this is expected to result in a mixture of dialkoxyethylaluminum and trialkoxyaluminum, with the displaced ethyl groups having been converted into ethane. When terminal alcohol groups are introduced, for example, by reaction with ethylene oxide, addition of the alcohol also results in an equilibrium level of protonation of the polymer chain ends. Methanol is preferred in this case as the resulting equilibrium favors protonation of chain ends. If a less acidic alcohol, such as 2-ethylhexanol, is used, the polymer cement may exhibit the properties of a weak gel. Presumably, this is due to interaction of ionized chain ends with the alkoxy (alkyl) aluminum products. This step may be omitted. However, partial hydrolysis of the terminal "ate" complex leads to Al-O-Al bonds. In the absence of vigorous mixing, this can result in the temporary formation of a rather strong gel during the wash process. Also, this hydrolysis liberates substantial quantities of ethane gas, leading to problems with foaming. Hydrolysis of the alcohol reaction products is slower, leading to less problems with gel formation in wash, and does not liberate ethane as vigorously. For these reasons, it is generally desirable to terminate the polymerization with an alkanol after functionalization.

The polymer solution is then washed with aqueous acid. Mineral acids (phosphoric, sulfuric, hydrochloric acids, etc.) are generally preferable, as these acids are inexpensive, readily available, and have little tendency to partition into the organic phase. Acids that partition into the organic phase may interfere with hydrogenation. The quantity and strength of the acid used are chosen so that the salts that are produced are soluble. If phosphoric acid is used, it is preferable to add a sufficient quantity to supply 1 mole of acid per mole of lithium and at least 3 moles of acid per mole of Al . It is also preferable to use a relatively concentrated acid solution at a relatively low aqueous acid phase weight ratio. For a 20% solids content in the cement wherein the polymerization targets a molecular weight of about 4,000, it is most preferable to conduct the wash using 20% wt . to 40%wt. aqueous phosphoric acid at a aqueous acid phase weight ratio between about 0.1:1 and 0.25:1 aqueous acid: cement and at a temperature of about 45 °C to 55 °C. Although this extraction is relatively insensitive to mixing conditions, it is preferable to avoid unnecessarily high shear. The cement should be allowed to settle until substantially free of entrained water. The - 16 -

wash can be performed under conditions of minimal dispersion ("dancing interface") contact, which results in very little entrainment of the aqueous acid in the organic phase, or by more vigorous mixing, followed by settling. The water concentration by Karl Fisher titration should then be on the order of 400 ppm. Surprisingly, the efficiency of hydrogenation of these cements with the standard Ni/Al catalyst was found to comparable to dry, aluminum-free solutions of comparable polymers. The Ni/Al catalyst can then be extracted into aqueous acid and the liquid polymer product isolated by devolatization .

The washing step ensures that the hydrogenation step is much faster and requires less catalyst than without the washing step. It would, however, be advantageous if the washing step prior to the hydrogenation step could be omitted, whilst still retaining the fast, catalyst efficient hydrogenation process.

It has further been found that the washing step. prior to the hydrogenation step can be omitted if a proton source of a certain pKa is added in certain amounts.

Therefore, according to a further aspect, the present invention relates to a process for making gel-free hydrogenated functionalized anionic polymers using multi- lithium initiators which comprises:

(a) anionically polymerizing at least one monomer with a multi-lithium initiator in a hydrocarbon solvent,

(b) functionalizing the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly-associating chain ends are formed resulting in a polymer gel,

(c) adding a trialkyl aluminum compound to the polymer gel whereby the gel dissipates,

(d) adding a sufficient amount of a proton source to provide at least 1 mole of protons per mole of lithium ions and at least 2 moles of protons per mole of aluminum wherein the proton source is an organic acid with a pK_a of 11 or less or a mixture of the organic acid and an alkanol, provided that sufficient organic acid is added to provide at least 0.4 moles of protons per mole of lithium ions,

(e) hydrogenating the polymer with a hydrogenation catalyst, and

(f) optionally washing the terminated polymer with aqueous mineral acid.

According to an alternative embodiment, the present invention relates a process for making gel-free hydrogenated functionalized anionic polymers using multi- lithium initiators which comprises: (a) anionically polymerizing at least one monomer with a multi-lithium initiator in a hydrocarbon,

(b) adding a trialkyl aluminum compound before or during the polymerization or before or at the same time as the capping agent, and (c) functionalizing the polymer by adding to the polymer a capping agent which, in the absence of the trialkylaluminum compound, would react with the polymer chain ends to form strongly-associating chain ends resulting in a polymer gel, (d) adding a sufficient amount of a proton source to provide at least 1 mole of protons per mole of lithium ions and at least 2 moles of protons per mole of aluminum wherein the proton source is an organic acid with a pKa of 11 or less or a mixture of the organic acid and an alkanol, provided that sufficient organic acid is added to provide at least 0.4 moles of protons per mole of lithium ions,

(e) hydrogenating the polymer with a hydrogenation catalyst, and - 18 —

(f) optionally washing the terminated polymer with aqueous mineral acid.

The polymer is optionally washed with aqueous acid to extract the lithium and catalyst residue. Optionally, the polymer is further washed with water or aqueous base to extract the organic acid.

In the reagent that it the proton source, there must be at least 1 mole of protons per mole of lithium ions in the polymer cement and at least 0.4 of those must come from the organic acid, preferably from 0.5 to 1. There must also be at least 2 moles of protons per mole of aluminium in the polymer cement. The organic acid can be a carboxylic acid such as citric acid, a mineral acid ester such as di-2-ethylhexylphosphoric acid, and an aromatic alcohol such as phenol since these are acids and have a pKa of 11 or less.

It has been known to reduce the basicity in the functionalized polymer cements by adding methanol. The hydrogenation of this methanol-neutralized cement is difficult in the presence of aluminium alkyl. We have found that if an organic proton source which has a pKa of 11 or less is added to the cement at this point in the process, the hydrogenation of the cement is greatly enhanced. Adding an aromatic alcohol, carboxylic acid, or other organic compound that is more acidic than methanol (has a pKa of 11 or less) , alone or in addition to methanol or another alkanol in the neutralization step has been found to greatly improve hydrogenation catalyst performance. In general, the best results were obtained when at least one proton from the organic acid was present per mole of polymer (0.5 protons per lithium) . Thus, this invention provides a simpler process for making hydrogenated telechelic polymers, particularly telechelic diol polymers . pKa values for representative - 19 - organic compounds are tabulated in J. March "Advanced Organic Chemistry, 4th Edition," (pages 250-251) .

There must be at least 1 mole of protons per mole of lithium ions in the polymer cement. The practical range of operation is a total proton to lithium ion mole ratio of 1:1 to 5:1, preferably 1:1 to 1.5:1. At least 0.4 moles of the protons must come from the organic acid which has a pKa of 11 or less, preferably from 0.5 to 1 moles. There must also be at least 2 moles of protons per mole of aluminium in the polymer cement. All of the protons can be provided by the organic acid but it is also acceptable, within the foregoing limitations, to use an alkanol, such as methanol, ethanol, propanol, butanol and 2-ethylhexanol . Organic acids which can be used herein include aromatic alcohols such as phenol, 4-t- butylcatechol, catechol, m-cresol, p-cresol, 2,6-di-t- butyl-4-methylphenol, and hydroquinone, carboxylic acids such as citric acid, 2-ethylhexanoic acid, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, steric acid and the like, and mineral acid esters such as di-2-ethylphosphoric acid, and mono-2- ethylhexylphosphoric acid.

The optimum ratio of organic acid to polymer chains and, therefore, to lithium ions and aluminium, depends on the choice of acid, but is related to both the strength

(pKa) and functionality (number of acid protons per mole) of the organic acid. The optimum ratios are readily determined experimentally as shown in the examples. Relatively strong acids, such as carboxylic acids and mineral acid esters (which have a pKa of less than 5), are preferentially added so as to introduce 0.4 to 0.6 moles of acidic protons per lithium ion (about 1 mole per polymer chain for the polymers exemplified herein) . For most phenolic or aromatic alcohol acids, which are generally weaker acids than the foregoing, it is - 20 - preferably to provide at least 0.8 mole of phenolic protons per lithium ion. While the acid can be used as the sole source of the protons, it is preferred that an alkanol be used to provide at least some of the protons because of the problems that some acids can cause to the process and the process equipment. It is not necessary to add more than 2 moles of protons per mole of aluminium. With the exception of citric acid, adding more of the organic acid is not deleterious to hydrogenation performance in this range. However, additional acid results in little improvement in hydrogenation performance, while adding to the cost and complicating the recovery of the polymer. A practical range of operation is a ratio of protons from acid to lithium ions of 0.4:1 to 2:1, preferably 0.5:1 to 1:1.

In addition to the protons provided for the lithium ions, there must be at least 2 moles of protons provided per mole of aluminium. Preferably there are at least 3 moles of protons provided per mole of aluminium. The protons for aluminium can come from the acid, the alkanol, or both. As for the lithium, it is not necessary to add more than 3 moles per mole of aluminium. A practical range of operation is a ratio of protons to aluminium of 2:1 to 5:1, preferably 3:1 to 3.5:1. It is thus seen that it is important that the sum of the moles of protons available from the organic acid and the alkanol (generally methanol) is at least about equal to the number of moles of lithium ions plus twice the number of moles of aluminium. It is most preferable to add the organic acid after functionalization (capping), but prior to hydrogenation, and it is most preferable for the sum of moles of protons added to equal the sum of the moles of lithium ions and 3 times the moles of aluminium. If the polymer is di-initiated and the trialkylaluminium is added at a 1:1 ratio, as in these examples, these - 2 1 -

ratios can be easily expressed relative to the number of moles of polymer chains (assuming quantitative initiation by the di-initiator) . Thus, it becomes preferable to add a sufficient quantity of alkanol and organic acid to provide at least six moles of protons per chain, most preferably eight.

For the purpose of these calculations, every carboxylic acid or phenolic alcohol functional group is assumed to be active. Thus, catechol ( 1, 2-dihydroxy- benzene) is assumed to contribute two equivalents of acidic protons per mole and citric acid is assumed to contribute three equivalents of acidic protons per mole.

There are a number of possible explanations for the inhibition of hydrogenation in the presence of organoaluminium compounds observed above. The products of alkylaluminium compounds and alcohols may still be reactive towards the catalyst, either blocking active sites or bridging particles, increasing the particle size and thus lowering the effective surface area. Also,. addition of methanol does not truly neutralize the capped, such as with ethylene oxide, chains. The pKa of methanol is only slightly lower than that of higher aliphatic alcohols. It is likely that a significant population of lithium alkoxide-terminated chains is present even after methanol termination. Interaction of these chains with the catalyst may contribute to the difficulties encountered in hydrogenation, particularly in the presence of organoaluminium compounds. Phenols, mineral acid esters, and carboxylic acids are much more acidic than aliphatic alcohols. It is believed that their presence greatly decreases the concentration of ionized polymer chain ends. The poor performance observed when only two equivalents of the acid, and no alcohol, was added (see the Examples) suggest a role for the aluminium-alkyl (Al-R) bonds as well as the O-Li bonds. In addition to its impact on hydrogenation, the downstream impact of the organic acid must be considered. Although low levels of the acids are tolerable in the final product, the majority of the acid must be removed. It is preferable to chose a phenol with enough volatility to be removed along with the solvent during the devolatilization of the polymer cement which is part of the normal finishing of these polymers. Relatively low molecular weight phenols (phenol, cresol, catechol) are preferred over highly alkyl-substituted phenols such as 4-t-butylcatechol and butylatedhydroxytoluene (BHT) , based on both of these considerations. Carboxylic acids as high in molecular weight as 2-ethylhexanoic acid can be extracted into aqueous base. Aqueous ammonium hydroxide is preferred over solutions of mineral bases such as sodium hydroxide or potassium hydroxide. Any residual ammonium hydroxide will be driven off as ammonia in the devolatilazation of the polymer cement.

Telechelic hydrogenated butadiene (EB) diol polymers within the scope of this invention are prepared by the following process. Butadiene is polymerized by a difunctional alkyl lithium initiator, such as is obtained by reacting two moles of an alkyl lithium reagent with one mole of diisopropenylbenzene, in a solvent consisting of a hydrocarbon, such as cyclohexane, and an ether microstructure modifier. After polymerization is complete, one equivalent (basis Li) of a trialkylaluminum compound such as triethylaluminum is added. At least one equivalent of ethylene oxide is added to introduce the desired hydroxyl endgroups (the capping reaction) . Then the polymer is terminated with a mixture of methanol and an acid as described. This mixture is formulated to meet the following criteria: (1) provide a total of 8 moles of protons per diinitiated polymer chain (at least one equivalent of protons from the alkanol or the more acidic organic acid per mole of lithium and three equivalents per mole of Al), and (2) provide that at least one equivalent (preferably 2 equivalents if the organic acid is a phenol) of protons are from the more acidic organic acid (1 equivalent of protons per equivalent of Li) .

Hydrogenation can then be accomplished under conditions typical for these polymers with the standard hydrogenation catalysts, such as those described below. Subsequent to hydrogenation, the polymer solution is optionally washed with aqueous mineral acid. It is important to select the acid strength and relative quantity of aqueous acid (phase ratio) so as to insure that all of the metal salts are soluble. If phosphoric acid is used, it is preferable to add a sufficient quantity to supply 1 equivalent of acid per equivalent of lithium and at least 3 equivalents of acid per mole of Al . It is also preferable to use a relatively concentrated acid solution at a relatively low phase weight ratio. For a 20% solids content in the cement wherein the polymer has a molecular weight of about

4,000, it is most preferable to conduct the wash using 20 %wt to 40 %wt aqueous phosphoric acid at a phase weight ratio between about 0.1:1 and 0.25:1 aqueous acid: cement and at a temperature of about 45 °C to 55 °C. Although this extraction is relatively insensitive to mixing conditions, it is preferable to avoid unnecessarily high shear. The cement should be allowed to settle until substantially free of entrained water. It is preferable to minimize the mineral acid residues in the final product. In the case where the organic acid is a phenol, it is preferable to follow the acid wash with deionized water. The liquid polymer may then be isolated by devolatilization, preferably under vacuum. It is preferable to choose conditions that remove the majority of the phenol at the lowest practical temperature and -24- minimize exposure to oxygen during finishing. If the organic acid is a carboxylic acid or ester of a mineral acid, it is preferable to extract the acid into aqueous base, most preferably aqueous ammonium hydroxide, prior to devolatilization. EXAMPLES

Example 1 : : Procedure for Preparation of a Diinitiated

Butadiene Polymer at 10% Solids in a 1-gallon (3. .75 1) Stainless Steel Autoclave, Capping with Ethylene Oxide, and Breaking the Gel with Trialkylaluminum

A diinitiator solution was prepared by adding s-butyllithium to a solution of diisopropenyl benzene in cyclohexane and ether. The polymerization was carried out in a 1-gallon (3.75 1) stainless steel autoclave which was heated by means of a external jacket and a heated water circulation bath. The polymerization was carried out at a temperature of about 20 °C to 40 °C, adjusting charges for intended solids, according to the followinα procedure: 1445 grams of cyclohexane, 185 grams of diethyl ether, and 200 grams of 1, 3-butadiene were charged to the reactor and allowed to equilibrate to the desired temperature. All charges were made from pressure vessels or bombs under nitrogen. 172.41 grams of initiator solution (0.05 moles of diinitiator, 0.10 moles of lithium) were then added from a sample bomb. The temperature of the polymerization solution rose from 21.7 °C to 40 °C over a 43 minute period. In anionic polymerization, the number average molecular weight is determined by the molar ratio of monomer to initiator. In general, this ratio was chosen to produce a polymer, for the experiment in Table 1, with a number average molecular weight of about 4000. Before the addition of the ethylene oxide, the reactor stirrer speed was increased to 1000 rpm. We then pressured 30.8 grams of ethylene oxide, at 40 °C, into the reactor from a bomb. - 25 -

After addition of the ethylene oxide the stirrer almost stopped, indicating formation of gel. Attempts to remove any material from the sample port did not succeed. At an applied pressure of greater than 50 psi (344.7 kPa) , no flow was observed suggesting that the yield stress of the material was in greater than 0.4 psi (2.76 kPa) . We allowed the ethylene oxide to react 1 hour. We then added 69.2 grams of 1 M triethylaluminum solution to the reactor and allowed it to stir for 23 minutes. The material in the reactor was no longer a gel as evidenced by our ability to remove samples easily from the reactor sampling port. The material was removed from the reactor into 20 %wt. aqueous H3PO4 which was used to remove lithium and aluminum from the solution. Example 2: Representative Procedure for Preparation of a Diinitiated Butadiene Polymer at 10% Solids in a 2 1. Glass Autoclave, Capping with Ethylene Oxide, and Breaking the Gel.

Diinitiator solutions were prepared by adding s- butyllithium to a solution of diisopropenyl benzene in cyclohexane and ether. The active concentration of the initiator was determined to be 0.47 N by titration. The polymerizations were carried out in a 2 liter Buchi glass autoclave which made any color or viscosity changes easy to observe. Unless otherwise specified, polymerizations were carried out at a temperature of about 35 °C to 40 °C, adjusting charges for intended solids, according to the following procedure: 590 grams of cyclohexane and 100 grams of diethyl ether were charged to the reactor and allowed to equilibrate to the desired temperature.

100 grams of butadiene were added. 83 grams of initiator solution were then added from a sample bomb, resulting in a temperature increase of about 10 °C to 20 °C . The reactor contents initially took on the red/orange color of the initiator solution, changing to yellow/orange and - 26 -

increasing in viscosity as the polymerization progressed. In anionic polymerization, the number average molecular weight is determined by the molar ratio of monomer to initiator. In general, this ratio was chosen to produce polymers on a number average molecular weight of about

4,000. A bomb containing 2.2 grams of ethylene oxide (EO) was connected to the reactor and a bomb containing 34.6 grams of a 16.5 %wt . triethylaluminum solution was attached to it. The valves of the sample bombs were then opened sequentially, starting at the valve closest to the reactor, so that the EO was added first, followed very rapidly by the alkyl aluminum solution. Reaction with EO is very fast, so gel was observed to form. This gel broke very rapidly, yielding a pale yellow, freely flowing, low viscosity solution. The yield stress was less than 1 psi (6.89 kPa) , likely less than 0.1 psi (0.69 kPa) . Methanol was added after 1 hour to terminate the reaction. Details of this and other similar experiments are summarized in Table 1.

Table 1. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers, Capping with EO, Followed by Addition of TEA to Break the Gel.

Capping Reaction Sample* solids [DiLi] (N) RLi R₃A1 TEA:Li t_rxn EO/Li

(min) 1 21452-179 10% 0.35 s-BuLi TEA ΪTΪ 60 7 . 0 22930-83C 10% 0.47 s-BuLi TEA 1:1 30 1 . 20 22930-84B 10% 0.47 s-BuLi TEA 1:1 30 1 . 16

^Time interval between addition of TEA and addition of methanol . -27-

Example 3 : : Representative Procedure for Preparation of a

Diinitiated Butadiene Polymer at 10% Sol .ids in a . 1-gallon Stainless Steel Autoclave with Trialkylciluminum Present

During the Polymerization (sample 23749-121) This polymer was made essentially as the polymer in the Example 2 with the exception that 0.5 moles of triethylaluminum per mole of lithium were present from the beginning of the polymerization. 28.07 grams of 25.4% triethylaluminum in hexane was mixed with 232 grams of diinitiator made as in the previous example. This mixture was added to the reactor which contained proper charges of cyclohexane, diethoxypropane (DEP-0.4 grams) diethylether, and butadiene. Synthesis conditions for this experiment regarding preparation of diinitiated butadiene polymer with trialkylaluminium present during polymerization, then capping with EO is summarized in Table 2. Viscosity results for the polymer sample are in Table 5. Example 4: Representative Procedure for Preparation. of a Diinitiated Butadiene Polymer at 20% Solids in a 1-gallon Stainless Steel Autoclave and Capping with EO after adding Trialkyaluminum. (23749-113)

A diinitiator solution was prepared by adding s-butyllithium to a solution of diisopropenyl benzene in cyclohexane and ether. The active concentration of the initiator was determined to be 0.42 N by titration. The polymerizations were carried out in a 1-gallon stainless steel autoclave. Temperature control for the autoclave was provided by a water bath which circulated water through its external jacket. In addition, for these experiments, a chilled water circulator set at 5 °C was used to cool the autoclave as necessary. Unless otherwise specified, polymerizations were carried out at a temperature of about 35 °C to 40 °C, adjusting charges for intended solids, according to the following - 28 -

procedure: 973 grams of cyclohexane, 120 grams of diethyl ether. In this experiment, and in others as noted in Table 2, we added 0.4 grams of 1, 2-diethoxypropane (DEP) in 20 grams of cyclohexane. We then charged 200 grams of butadiene (one-half of the final charge) and we allowed the autoclave to equilibrate to the desired temperature. 464 grams of initiator solution was then added from a sample bomb. In anionic polymerization, the number average molecular weight is determined by the molar ratio of monomer to initiator. In general, this ratio was chosen to produce polymers, for the experiments in Table 2, with a number average molecular weight of about 3200 AMU. We used the chiller to maintain a temperature near 40 °C throughout the polymerization. After 45 minutes the reactor temperature was 40.5 °C and we used the chiller to bring it down to 31.4 °C . We added 200 grams more of butadiene. The polymerization exothermed to 56 °C in spite of constant chilling. After 90 minutes of polymerization the reactor temperature was 40.2 °C and we added 173 grams of 16.5 %wt triethylaluminum solution to the reactor, and then allowed it to stir for 15 minutes. We then added 13.9 grams of ethylene oxide to the reactor and allowed it to react for 1 hour. The solution was free flowing as evidenced by the fact we could remove samples from the sample port. Methanol was added to terminate the reaction. Details of this and other experiments are summarized in Table 2. Example 5: Representative Procedure for Preparation of a Diinitiated Butadiene Polymer at 20% Solids in a 2 1. Glass Autoclave and Capping with EO after adding Trialkyaluminum.

Diinitiator solutions were prepared by adding s-butyllithium to a solution of diisopropenyl benzene in cyclohexane and ether. The active concentration of the initiator was determined to be 0.48 N by titration. The - 29 - polymerizations were carried out in a 2 liter Buchi glass autoclave which made any color or viscosity changes easy to observe. Unless otherwise specified, polymerizations were carried out at a temperature of about 35 °C to 40 °C, adjusting charges for intended solids, according to the following procedure: 350 grams of cyclohexane and 100 grams of diethyl ether were charged to the reactor and allowed to equilibrate to the desired temperature. 100 grams of butadiene were added. 203 grams of initiator solution was then added from a sample bomb, resulting in a temperature increase of about 10 °C to 20 °C . After about 30 to 40 minutes, another 50 grams of butadiene was added. A third 50 g. aliquot was added after an additional 15 to 20 minutes. After a total reaction time of about 90 to 120 minutes (estimated to be about 8 to 10 half-lives), 57 grams of 25 %wt triethylaluminum solution was added, and allowed to react with the living chain ends for 15 minutes. The reaction was exothermic enough to raise the temperature a few degrees. The yellow color of the polymer anion persisted, but the solution viscosity decreased noticeably, especially at higher polymerization solids. After 15 minutes, 6 grams of ethylene oxide charge was added and flushed in with about 44 grams of cyclohexane from a bomb attached above it, as described in the previous example, resulting in a temperature increase of a few degrees and a decrease in the color of the solution, but no increase in the viscosity. After 30 minutes, methanol was added to terminate the reaction. Details of this and other experiments are summarized in Table 2. - 30 -

Table 2. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and Capping with EO Aftςr Addition of Trialkylaluminum.

Capping Reaction

Sample* solids [DiLi] RLi R3AI TEA:Li t_rxn EO/Li DEP

(N) (min)

23749-75 5% 0.48 s-BuLi None 0:1 na 1. ,49 Y

23749-79 5% 0.48 s-BuLi TEA 1:1 15 1. ,34 Y

23749-81 5% 0.56 s-BuLi TEA 0.67:1 15 1. ,44 Y

23749-83 5% 0.56 s-BuLi TEA 0.33:1 15 1. ,44 Y

21452-175 10% 0.35 s-BuLi TEA 1:1 15 1. ,26 N

21452-185 10% (1) s-BuLi None 0:1 na 4. ,4 N

21452-189 30% (1) s-BuLi None 0:1 na 3. ,3 N

23749-85 10% 0.56 s-BuLi TEA 1:1 15 1. ,47 Y

23749-87 10% 0.56 s-BuLi TEA 0.67:1 15 1. .58 Y

23749-89 10% 0.56 s-BuLi TEA 0.33:1 15 1. .52 Y

23749-97 30% 0.52 s-BuLi TEA 1:1 15 1. .6 Y

23749-101 30% 0.52 s-BuLi TEA 0.67:1 15 1, .56 Y

23749-113 20% 0.42 s-BuLi TEA 1:1 15 1. .26 Y

23749-121 10% 0.42 s-BuLi TEA 0.5:1 Lengt 1. .4/1 Y h of poly

22930-99A 20% 0.49 t-BuLi TEA 1:1 15 3. .08 N

22930104C 20% 0.57 t-BuLi TEA 1:1 15 2. .43 N

22930-105A 20% 0.57 t-BuLi TEA 1:1 15 3. .21 N

22930-107B 20% 0.5 t-BuLi TEA 1:1 15 2, .41 N

22930-91A 10% 0.38 s-BuLi TMAL¹ 1:1 15 3, .01 N

22930-102A 20% 0.52 s-BuLi TEA 1:1 15 2. .58 N

22930-103A 20% 0.61 s-BuLi TEA 1:1 15 2 .54 N

22930-109B 10% 0.57 s-BuLi TEA 1:1 15 1 .47 N

23838-13 10% 0.48 s-BuLi TEA 1:1 15 1 .38 N

23838-16 10% 0.48 s-BuLi TEA 1:1 15 1 .58 N

23838-20 10% 0.48 s-BuLi TEA 1:1 15 1 .32 N 23838-22 10% 0.48 s-BuLi TEA 1:1 15 1 .52 N - 31 -

Table 2 (cont'd). Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and Capping with EO After Addition of Trialkylaluminum.

Capping Reaction

Sample* solids [DiLi] RLi R A1 TEA: Li t_rxn EO/Li DEP

<^N> (min)

23838-24 20% 0. ,48 s-BuLi TEA 1:1 15 1.37 N

23838-26 10% 0. .48 s-BuLi TEA 1:1 15 1.35 N

23838-28 10% 0. .48 s-BuLi TEA 1:1 15 1.47 N

23838-30 10% 0. .52 s-BuLi TEA 1:1 15 1.38 N

23838-32 10% 0. .52 s-BuLi TEA 1:1 15 1.24 N

23838-34 10% 0, .52 s-BuLi TEA 1:1 15 1.59 N

23838-36 10% 0. .52 s-BuLi TEA 1:1 15 1.17 N

23838-38 10% 0. .52 s-BuLi TEA 1:1 15 1.29 N

23838-40 10% 0, .52 s-BuLi TEA 1:1 15 1.39 N 23838-43 10% 0, .52 s-BuLi TEA 1:1 15 1.38 N

(1) made in situ in autoclave

^-Trimethylaluminum

^Triethylamine used in initiator synthesis instead of DEE.

Example 6: Representative Procedure for Preparation of a

Diinitiated . Butadiene Polymer at 105 Solids in a 2 1. Glass Autoclave and Reaction with a Mixture of EO and

Trialkyaluminum. Diinitiator solutions were prepared by adding t-butyllithium to a solution of diisopropenyl benzene in cyclohexane and ether. The active concentration of the initiator was determined to be 0.44 N by titration. The polymerizations were carried out in a 2 liter Buchi glass autoclave which made any color or viscosity changes easy to observe. Unless otherwise specified, polymerizations were carried out at a temperature of about 35 °C to 40 °C, adjusting charges for intended solids, according to the following procedure: 590 grams of cyclohexane and 100 grams of diethyl ether were charged to the reactor and allowed to equilibrate to the desired temperature. 100 grams of butadiene were added. 88.6 grams of initiator solution was then added from a sample bomb, resulting in a temperature increase of about 10 °C to 20 °C. The reactor contents initially took on the red/orange color of the initiator solution, changing to yellow/orange and increasing in viscosity as the polymerization progresses. Two bombs, one containing 2.4 grams of EO and the other 34.6 grams of an approximately 16.5% wt . solution of triethylaluminum (TEA) in hexane, were attached to the reactor as described above. When the polymerization was complete, the TEA solution was pressured into the bomb containing the EO and allowed to interact for about one minute. The contents were then pressured into the autoclave and allowed to react with the living chain ends for 30 minutes. While the heat of mixing of the EO and TEA was appreciable, ^XH NMR of the mixture suggested that the reaction between EO and TEA was relatively slow under these conditions. As in the previous example, no increase in viscosity was observed on addition of the mixture and the color faded to pale yellow, indicative of capping. After 30 minutes, methanol was added to terminate the reaction. Details of this and other experiments are summarized in Table 3.

- 33

Table 3. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and Capping with a Mixture of EO and TEA.

Capping Reaction

Sample* solids [DiLi] (N) Rli R₃A1 TEA:Li t_rxn EO/Li

(min) 1

90A 10% 0, .38 sBuLi TEA 1:1 1 2.3

93B 10% 0. .44 tBuLi TEA 1:1 1 2.40

98A 15% 0, .49 tBuLi TEA 1:1 1 2.63 98B 20% 0, .49 tBuLi TEA 1:1 1 2.58

^Time TEA and EO allowed to mix before addition to autoclave .

^Triethylamine used in initiator synthesis instead of DEE.

Yield Stress and Viscosity Measurements

Yield stress and viscosity measurements for the polymers in Tables 4-7 were carried out using a modified melt flow device, and a steel tube attached to the polymerization reactor. Yield stress measurement

We measured yield stress using a modified melt flow device, which consisted of a barrel, plunger, die, and several standard weights . We placed the apparatus into a nitrogen-filled glove box. The atmosphere in the glove box was monitored by sensors, and had <10 pp moisture and oxygen. To measure a sample, we removed a sample of polymer (gel) from the autoclave into a nitrogen-purged bottle, then took the sample into the glove box. We placed the die into the melt flow barrel, placed a small quantity of polymer into the barrel, put in the plunger, then added weight until the material just began to - 34 -

extrude from the die. The amount of weight necessary to cause flow was used to calculate the yield stress as follows :

w = stress (dynes/cm²) - this value is yield stress when the weight just causes polymer flow through the die R,j = die radius (cm)= .104775 cm

W = weight added to plunger (gm) L,-₎ = die length (cm)= 0.8001 cm

PD = plunger diameter = 0.9525 cm w = (R * (W/π* (PD/2)²) *980.6 dynes/gram) / (2L_d)

Viscosity Measurement

We measured viscosity using a tube attached to the polymerization reactor. The tube was made of 316 stainless steel, 0.476 cm in diameter, and 6.19 cm in length, and was attached to the drain port of the reactor. Polymer samples were taken through the tube int; tared, nitrogen-purged bottles that were vented with a needle. The sample was timed, then weighed, and the viscosities were calculated as follows: R_c = capillary/tube radius (cm)

L_c = capillary/tube length (cm)

Q = (grams polymer collected/second) / (polymer solution density)

Polymer solution density = 0.78 grams/cm^ A = capillary/tube cross-section area = π * (.149 cm) 2 =

.0697 cm² V_z = Q/A

ΔP = psig on reactor converted as follows:

(psig*445000) / (2.54) ² = dynes/cm² η = (R_c ²/8 (V_z) ) * (ΔP/L_C) Table 4. Yield Stress and Rheology Data for 5 wt% Solutions of Dilithium Initiated Diol Polymers. The Affect of Added Trialkylaluminum Reagent on Properties. o

Sample* MW R3AI R3Al:Li Order of Yield Viscosity

(type) (mol: ol) Addition Stress (Shear Rate)

(psi) centipoise

(1/sec)

23749-79 4,405 TEA 1:1 Before EO <1 (BDL) <100 (BDL)

(-

23749-81 (*)2,896 TEA 0.67:1 Before EO <1 (BDL) 213(6,856)

141(8,634) 114 (10,636)

23749-83 (*)2,660 TEA 0.33:1 Before EO <1 (BDL) 306(7,968)

218 (11,151) 218 (11,175)

23749-75 3,004 None 0:1 None Added Gel (visual) NA

A3

H

13 δ

OoN

- 36 -

In most instances, molecular weight (MW) was measured using an Nuclear Magnetic Resonance (NMR) technique. Values denoted with ( * ) were assayed using a Gel Permeation Chromatograph (GPC ) method. The column labeled R3AI (type) is indicating the nature of the aluminum reagent that was used to mitigate the tendency of the product to gel, where TEA=triethylaluminum. The column labeled R3AI : Li is noting the stoichiometric relationship between the amount of Al reagent that was used as it related to the number of polymer chain ends in the sample. At a 1:1 ratio, there is an Al reagent for every polymer chain end. "Order of Addition" is an indication of the point in the synthesis process where the Al reagent was added. The choices were 1) "After EO" which is also after the gel had already formed, 2) "With EO" which is the case where the EO and the Al reagent are premixed before addition to the polymer (this method avoids the gel forming step) 3) "Before EO" which is after polymerization is over and before the capping^' agent was added; this process avoids the gel forming step) , and 4) "Before Bd" which is before the butadiene monomer was added; this method avoids the gel forming step) . "Yield Stress" was measured on samples having a value greater then lpsi (6.9 kPa) . Samples having lower, to include 0 psi, yield stress were too weak to be assayed by this method and were noted as Below Detectable Limit ("BDL") . Some samples clearly contained gel based on visual observation but were not assayed using the rheometer technique noted in the text. These samples were labeled "Gel (visual)". Where viscosity could be measured, it was reported in combination with the shear rate as "Viscosity (Shear Rate) ." Samples with very low viscosity (<100 cps) were visually observed to be "Below the Detection Limit" - 37 -

and were reported as "BDL". Most measurements were at 40 °C. NA=Not Analyzed by this method.

Table 5. Yield Stress and Rheology Data for 10 %wt Solutions of Dilithium Initiated Diol ^

O Polymers. The Affect of Added Trialkylaluminum Reagent on Properties. o o »--

Sample* MW R3AI R3Al:Li Order of Yield Stress Viscosity

(type) (mol: ol) Addition (psi) (Shear Rate) centipoise (1/sec)

23749-85 4,292 TEA 1:1 Before EO (1) 1,977(1,234)

2,033 (1,200) 1,503 (1, 622)

1,839(1,326) ,

23749-87 3,459 TEA 0.67:1 Before EO <1 (BDL) 279(4363) ∞

926(1316) '

392 (3109) 23749-121 3646 TEA 0.5:1 Before Bd <1 (BDL) 64,358(68)

64, 041 (68) 23749-89 (*)3,296 TEA 0.33:1 Before EO (1) 26,948(231)

22,087 (281) 16,373 (507)

15,427(538) ,

5,592(2,226) g

5,195(2,396) 3

© o σ\ o\

Table 5 (cont'd). Yield Stress and Rheology Data for 10 %wt Solutions of Dilithium Initiated Diol Polymers. The Affect of Added Trialkylaluminum Reagent on Properties. O o

Sample* MW R₃A1 R Al:Li Order of Yield Stress Viscosity (type; (mol :mol ' Addition (psi) 'Shear Rate!

21452-185 6,991 None 0:1 None Added 1,422,000 (21. kPa'

1, , 181,000 (30

22930- -83C 3,700 TEA 1:1 After EO (BDL) < 100

22930- -84B 3,790 TEA 1:1 After EO (BDL) < 100

22930- -91A 3,800 TMAL 1:1 After EO (BDL) < 100 CO

22930- -109B 4,358 TEA 1:1 After EO (BDL) < 100

23838- -13 2,957 TEA 1:1 After EO (BDL) < 100

23838- -16 4,018 TEA 1:1 After EO (BDL) < 100

23838- -20 3,887 TEA 1:1 After EO (BDL) < 100

23838- -22 4,169 TEA 1:1 After EO (BDL) < 100

23838- -26 3, 940 TEA 1:1 After EO (BDL) < 100

23838- -28 4,020 TEA 1:1 After EO (BDL) < 100

23838- -30 4,013 TEA 1:1 After EO (BDL) < 100

23838- -32 3,619 TEA 1:1 After EO (BDL) < 100 o •0

23838- -34 4,622 TEA 1:1 After EO (BDL) < 100 23838- -36 3,414 TEA 1:1 After EO (BDL) < 100 oo as -a

Table 5 (cont'd). Yield Stress and Rheology Data for 10 %wt Solutions of Dilithium Initiated Diol Polymers. The Affect of Added Trialkylaluminum Reagent on Properties.

;© o

Sample* MW R3AI R3Al:Li Order of Yield Stress Viscosity (type) (mol:mol) Addition (psi) (Shear Rate]

23838-38 3,757 TEA 1:1 After EO <1 (BDL) < 100 23838-40 4, 050 TEA 1:1 After EO <1 (BDL) < 100 23838-43 4,009 TEA 1:1 After EO <1 (BDL) < 100

22930-90A 3,947 TEA 1:1 With EO <1 (BDL) < 100 22930-93B 4,358 TEA 1:1 With EO <1 (BDL) < 100 .0 o

"ø O H

-3 vo δo as

ON

- 4 1 -

(1) Flowable at pressure at which viscosity measurements were taken (last column after viscosities) . In most instances, molecular weight (MW) was measured using an Nuclear Magnetic Resonance (NMR) technique. Values denoted with (*) were assayed using a Gel Permeation Chromatograph (GPC ) method. The column labeled R₃A1

(type) is indicating the nature of the aluminum reagent that was used to mitigate the tendency of the product to gel where TEA=triethylaluminum and TMAL = trimethyl- aluminum. The column labeled R3Al:Li is noting the stoichiometric relationship between the amount of Al reagent that was used as it related to the number of polymer chain ends in the sample. At a 1:1 ratio, there is an Al reagent for every polymer chain end. "Order of Addition" is an indication of the point in the synthesis process where the Al reagent was added. The choices were 1) "After EO" which is also after the gel had already formed, 2) "With EO" which is the case where the EO and the Al reagent are premixed before addition to the ' polymer (this method avoids the gel forming step), 3) "Before EO" which is after polymerization is over and before the capping agent was added (this process avoids the gel forming step), and 4) "Before Bd" which is before the butadiene monomer was added (this method avoids the gel forming step) . "Yield Stress" was measured on samples having a value greater then lpsi. Samples having lower, to include 0 psi, yield stress were too weak to be assayed by this method and were noted as Below Detectable Limit ("BDL") . Some samples clearly contained gel based on visual observation but were not assayed using the rheometer technique noted in the text. These samples were labeled "Gel (visual)". Where viscosity could be measured, it was reported in combination with the shear rate as "Viscosity (Shear Rate) ." Samples with very low viscosity (<100 cps) were visually observed to be "Below - 42 -

the Detection Limit" and were reported as "BDL" . Most measurements were at 40 °C. NA=Not Analyzed by this method. The viscosity of samples prepared in the glass autoclave was estimated from the approximate time it took to recover a sample from a DOPAC sample port. About

25 grams of sample could be collected in about 5 seconds with a head pressure of about 30 psig. The sampler is basically a sample needle, a vent needle, and a cage for the sample bottle. Sample bottles are capped with a septum. Pushing the bottle into the cage forces both needles through the septum. Based on a drawing provided by the manufacturer, the sampler was modeled as a capillary, 1.57 inches in length an 0.053 inches in diameter. None of these values were measured with high precision. The value of < 100 cp . should be taken as an order of magnitude estimate.

Table 6. Yield Stress and Rheology Data for 20 wt% Solutions of Dilithium Initiated Diol Polymers. The Affect of Added Trialkylaluminum Reagent on Properties.

Sample* MW R3AI R3Al:Li Order of Yield Viscosity o I type) (mol:mol) Addition stress (Shear Rate] [psi) centipoise (1/sec)

23749- -113 3,042 TEA 1:1 Before EO <1 (BDL) NA

22930- -99A 4, 639 TEA 1:1 Before EO <1 (BDL) < 100

22930- ^■104C(*) 4, 669 TEA 1:1 Before EO <1 (BDL) < 100

22930- -105A 3, 970 TEA 1:1 Before EO <1 (BDL) < 100

22930- -107B 4,013 TEA 1:1 Before EO <1 (BDL) < 100

22930- -102A 4,859 TEA 1:1 Before EO <1 (BDL) < 100

22930- ^■103A(*) 5, 000 TEA 1:1 Before EO <1 (BDL) < 100

23838- -24 4,268 TEA 1:1 Before EO <1 (BDL) < 100 22930- -98B 4,358 TEA 1:1 With EO <1 (BDL) < 100

n H

13 vo δo ON as -4

- 4 4 -

(1) Flowable at pressure at which viscosity measurements were taken (last column after viscosities) . In most instances, molecular weight (MW) was measured using an Nuclear Magnetic Resonance (NMR) technique. Values denoted with (*) were assayed using a Gel Permeation Chromatograph (GPC ) method. The column labeled R3AI

(type) is indicating the nature of the aluminum reagent that was used to mitigate the tendency of the product to gel where TEA=triethylaluminum and TMAL = trimethyl- aluminum. The column labeled R3AI : Li is noting the stoichiometric relationship between the amount of Al reagent that was used as it related to the number of polymer chain ends in the sample. At a 1:1 ratio, there is an Al reagent for every polymer chain end. "Order of Addition" is an indication of the point in the synthesis process where the Al reagent was added. The choices were 1) "After EO" which is also after the gel had already formed, 2) "With EO" which is the case where the EO and the Al reagent are premixed before addition to the polymer (this method avoids the gel forming step), 3) "Before EO" which is after polymerization is over and before the capping agent was added (this process avoids the gel forming step), and 4) "Before Bd" which is before the butadiene monomer was added (this method avoids the gel forming step) . "Yield Stress" was measured, on samples having a value greater then lpsi. Samples having lower, to include 0 psi, yield stress were too weak to be assayed by this method and were noted as Below Detectable Limit ("BDL"); some samples clearly contained gel based on visual observation but were not assayed using the rheometer technique noted in the text. These samples were labeled "Gel (visual)". Where viscosity could be measured, it was reported in combination with the shear rate as "Viscosity (Shear Rate) ." Samples with very low - 45 -

viscosity (<100 cps) were visually observed to be "Below the Detection Limit" and were reported as "BDL". Most measurements were at 40°C. NA=Not Analyzed by this method. The viscosity of samples prepared in the glass autoclave was estimated from the approximate time it took to recover a sample from a DOPAC sample port. About 25 grams of sample could be collected in about 5 seconds with a head pressure of about 30 psig. The sampler is basically a sample needle, a vent needle, and a cage for the sample bottle. Sample bottles are capped with a septum. Pushing the bottle into the cage forces both needles through the septum. Based on a drawing provided by the manufacturer, the sampler was modeled as a capillary, 1.57 inches in length an 0.053 inches in diameter. None of these values were measured with high precision. The value of < 100 cp . should be taken as an order of magnitude estimate.

Table 7. Yield Stress and Rheology Data for 30 wt% Solutions of Dilithium Initiated Diol _

O

Polymers. The Affect of Added Trialkylaluminum Reagent on Properties. if o

Sample* MW R R33AAI1 R R3₃AAIl :: LLii Order of Yield Stress Viscosity (Shear Rate)

(type) (mol :mol Addition (psi) centipoise (1/sec)

23749-97 3642 T TEEAA 1 1::11 Before EO <1 (BDL) 565(3828) 23749-101 3469 T TEEAA 0 0..6677::11 Before EO <1 (BDL) 187(8486)

185 (16613) 21452-189 (*)3,365 None 0:1 None Added 11.03 10,570,000(7)

(76.1 kPa) 11.86 81.8 kPa) 7,105, 900(11)

3 O H

,3 δo OS -J

- 47 -

In most instances, molecular weight (MW) was measured using an Nuclear Magnetic Resonance (NMR) technique. Values denoted with (*) were assayed using a Gel Permeation Chromatograph (GPC ) method. The column labeled R3AI (type) is indicating the nature of the aluminum reagent that was used to mitigate the tendency of the product to gel, where TEA=triethylaluminum. The column labeled R3AI : Li is noting the stoichiometric relationship between the amount of Al reagent that was used as it related to the number of polymer chain ends in the sample. At a 1:1 ratio, there is an Al reagent for every polymer chain end. "Order of Addition" is an indication of the point in the synthesis process where the Al reagent was added. The choices were 1) "After EO" which is also after the gel had already formed, 2) "With EO" which is the case where the EO and the Al reagent are premixed before addition to the polymer (this method avoids the gel forming step) 3) "Before EO" which is after polymerization is over and before the capping agent was added; this process avoids the gel forming step) , and 4) "Before Bd" which is before the butadiene monomer was added; this method avoids the gel forming step) . "Yield Stress" was measured on samples having a value greater then lpsi. Samples having lower, to include 0 psi, yield stress were too weak to be assayed by this method and were noted as Below Detectable Limit ("BDL"). Some samples clearly contained gel based on visual observation but were not assayed using the rheometer technique noted in the text. These samples were labeled "Gel (visual)". Where viscosity could be measured, it was reported in combination with the shear rate as "Viscosity (Shear Rate) ." Samples with very low viscosity (<100 cps) were visually observed to be "Below the Detection Limit" and - 4 8 - were reported as "BDL". Most measurements were at 40 °C. NA=Not Analyzed by this method.

Comparative Example7 : Polymerization in a 2 1. Glass Autoclave and Capping with EO after adding Diethylzinc or Dibutylmagnesium.

Butadiene was polymerized at 20% solids using an initiator prepared from t-butyllithium and diisopropenyl benzene. After the polymerization was complete, one mole of diethylzinc was added per mole of lithium. As with trialkylaluminum, the viscosity of the living polymer solution decreased, while the color remained essentially unchanged. After 15 minutes, ethylene oxide was added (about 20% over the stoichiometric requirement) . The reactor contents immediately gelled. Within seconds, the reactor could not be stirred. Identical results were obtained with dibutylmagnesium. These metal alkyls appear to form complexes with the living chain ends that are capable of adding EO, but fail to prevent the resulting alkoxide from forming a gel. Example 8

Diol Synthesis Reactions

Synthesis conditions and characterization are described in Table 8. Unless otherwise specified, the initiators were prepared by adding two moles of either s-butyllithium or t-butyllithium to one mole of m-diisopropenylbenzene in cyclohexane in the presence of one mole of diethylether (DEE) per mole of lithium at a temperature of 20 °C to 50 °C . These initiators were used to polymerize butadiene in cyclohexane/10 %wt . DEE in a 2 liter glass autoclave, targeting a butadiene number average molecular weight of 4,000 or 3,200. The initiator fragment and EO endcaps add another 530. In general, molecular weights were close to predicted (basis titration of the initiator) and polydispersities were - 4 9 - relatively low, < 1.2. Polymer solids in the cements were varied from 10 %wt . to 20 %wt . At greater than 10% solids, the monomer was added in several increments. An attempt was made to keep the polymerization temperature below 50 °C. Vinyl contents in excess of 50% could be achieved if the average polymerization temperature was kept at or below about 25 °C. Triethylaluminum (TEA) was used to break up, or prevent gel and ethylene oxide (EO) was reacted with the living chain ends in order to introduce the desired hydroxyl endgroups . Unless otherwise specified, one mole of TEA was added per mole of chain ends. Ethylene oxide was generally added in an amount of at least 20%.

The capping reaction was carried out according to one of the following procedures: (1) A bomb containing (EO) was connected to the reactor and a bomb containing an approximately 16 %wt solution of triethylaluminum in hexane was attached to it. The valves of the sample bombs were then opened sequentially, starting at the valve closest to the reactor, so that the EO was added, followed very rapidly by the alkyl aluminum solution. Reaction with EO is very fast, so gel was observed to form. This gel broke very rapidly, yielding a pale yellow, freely flowing, low viscosity solution. (2) Two bombs, one containing the desired quantity of EO and the other containing the desired quantity of an approximately 16% wt . solution of triethylaluminum (TEA) in hexane, were attached to the reactor as described above. When the polymerization was complete, the TEA solution was pressured into the bomb containing the EO and allowed to interact for about one minute. The contents were then pressured into the autoclave and allowed to react with the living chain ends for 30 minutes. While the heat of mixing of the EO and TEA was appreciable, ^H NMR of the mixture suggested that the reaction between EO and TEA - 50 - was relatively slow under these conditions. No increase in viscosity was observed on addition of the mixture and the color faded to pale yellow, indicative of capping. (3) The desired quantity of about 16% to 25% wt . triethylaluminum solution was added and allowed to react with the living chain ends for 15 minutes. The reaction was exothermic enough to raise the temperature a few degrees. The yellow color of the polymer anion persisted, but the solution viscosity decreased noticeably, especially at higher polymerization solids. After

15 minutes, the EO charge was added and flushed in with about 44 grams of cyclohexane from a bomb attached above it, resulting in a temperature increase of a few degrees and a decrease in the color of the solution, but no increase in the viscosity. One polymerization, run

22930-83C, was performed at 0.5:1 TEA:Lι. The resulting solution was higher m viscosity, but much less so than is obtained in the absence of TEA. Unless otherwise specified, methanol was then added to "terminate" the polymerization. Sufficient methanol was added to provide 1 mole of methanol per mole of lithium and about 3.1 moles of methanol per mole of aluminum. For comparison, a polymerization was conducted at 10% solids, EO was added, and the resulting gel was allowed to stand until the color of the entire reactor contents changed from the red-orange of the polymer anion to the pale yellow of the EO - capped diol. An excess of methanol was added to break the gel. Table 8. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and

Capping with EO. so

NO !£ Polymerization Capping Reaction o

Mn Addition

Sample* RLi [DiLi] (N) % Solids ( ^λH NMR) Order TEA:Li ^rxn (min) 1 EO/Li

22930-82D s-BuLi 0.47 10% 3700 None overnight 1.3

22930-83C s-BuLi 0.47 10% 3700 EO 1st. 1:1 30 1.2

22930-84B s-BuLi 0.47 10% 3790 EO 1st. 1:1 30 1.2

22930-90A s-BuLi 0.38 10% 3950 Al to EO 1:1 1 2.3 1

22930-104C t-BuLi 0.57 20% 5290 Al 1st 1:1 15 2.4

22930-105B t-BuLi 0.57 20% 4970 Al 1st 1:1 15 3.2 1

22930-107B t-BuLi 0.5 20% 4470 Al 1st 1:1 15 2.4 22930-109B s-BuLi 0.57 10% 4360 Al 1st 1:1 15 1.5

1 Case (1) : time EO/TEA mixture is in contact with PLi prior to termination; Case (2) : time EO in contact with TEA prior to addition to PLi; Case (3) : time TEA in contact with PLi prior to EO addition.

-d O H

M A3 O NO δo aos.

Hydrogenation

Unless otherwise specified, hydrogenation reactions were carried out in a 1 gal (3.75 1). SS autoclave using a Ni/Al catalyst prepared by reacting triethylaluminum and nickel octoate (2:1 Al:Ni), according to the following general procedure. The polymer cement was charged to the autoclave and sparged with argon (if the transfer was not conducted under nitrogen) , and then with hydrogen. Only cements that had been washed were exposed to ambient atmosphere. The reactor was pressured up to 800 psi with hydrogen. The reactor temperature was adjusted to about 60 °C and then the first aliquot of catalyst solution was added. The autoclave was then heated to maintain a temperature of about 80 °C and reaction was allowed to proceed under 800 psi of H2

(5.5 MPa) for the desired time. Additional aliquots of catalyst were added as specified in Table 2 below. The catalyst was extracted with aqueous phosphoric acid (generally 20%wt) . The extent of hydrogenation was ^■ determined using 1H NMR. These results are summarized in Table 9. Samples for further testing were washed with deionized water until the pH of the settled aqueous phase was < 5 and then dried in a rotary evaporator. A number of attempts were made to hydrogenate the alcohol terminated polymer solutions. Methanol-terminated cements prepared at a TEA: Li ratio of 1:1 remained poorly hydrogenated after quite long reaction times at high catalyst loadings, as evidenced by runs 22930-84C and 22930-90B. When 2-ethylhexanol (2-EH) was substituted for methanol, the cement gelled on standing. It was necessary to add methanol to break the gel before the solution could be hydrogenated. Not surprisingly, hydrogenation was quite difficult. Hydrogenation of the cement prepared using an 0.5:1 ratio of TEA to Li was more facile, but still rather difficult. After reaction with a total of - 53 -

225 PPM Ni for a total reaction time of greater than 18 hours, 0.34 meq/g of residual unsaturation remained (98.0% conversion). The reactor was blocked-in at 800 psi hydrogen (5.5 MPa) overnight at ambient temperature after a total of 125 PPM Ni had been added. By comparison, the cement prepared at 10% solids without adding TEA was hydrogenated to a residual unsaturation of 0.18 meq/g (98.9% conversion) in 2 hours in the presence of only 125 PPM Ni The solution provided herein is to wash the aluminum and lithium out with aqueous acid prior to hydrogenation. It is unexpected that this would work well since the Ni/Al catalyst is known to be susceptible to deactivation by relatively low levels of water. For this reason, extraction with aqueous acid would not be anticipated to lead to improved hydrogenation performance unless followed by some operation to remove residual water. The catalyst was extracted using aqueous phosphoric acid. In all cases, sufficient H3PO4 was added to provide 1 mole of acid per mole of lithium, and 3 moles of acid per mole of aluminum. At this ratio the aluminum phosphate salts were observed to remain soluble in the aqueous phase. Use of phosphoric acid at concentrations of 20 %wt . to 40 %wt . allows for aqueous acid phase weight ratios (aqueous : organic) in the range of 0.1:1 to 0.25:1. Unless otherwise specified, these extractions were performed in a glass resin kettle (with indents to act as baffles) at about 50 °C to 60 °C.

The first pre-hydrogenation wash was carried out under minimally dispersive or "dancing interface" conditions, that is, the stir rate was set just below the point at which droplets of one phase began to break off and disperse into the other phase. Samples of the cement were collected and analyzed for water, aluminum, lithium, and phosphate during the extraction. This data is - 54 - summarized in Table 3. The initially clear cement began to turn cloudy and increase in viscosity until a very weak gel formed. As the extraction continued, the cement near the interface began to clear and decrease in viscosity. After an hour, the entire cement phase was once again clear and low in viscosity. These observations suggest the following sequence of events. Initially, little metal extraction occurs but water begins to diffuse into the cement and reacts with aluminum to produce a weak gel. As the extraction proceeds, the aluminum and lithium are pulled into the aqueous phase until finally the cement is substantially free of metals. Indeed, a cement sample taken at 20 minutes was very high in Al and Li, while the 60 minute sample contained only about 45 ppm Al and 7 ppm Li. As expected, the water and phosphate levels were low, 450 ppm and 10 ppm, respectively. Little change occurred on settling for 1 hour. This cement (105B) was then hydrogenated with no further treatment. As can be seen from Table 10 hydrogenation was quite facile. The residual unsaturation was decreased to 0.27 meq/g after reaction for 2 hours in the presence of 150 ppm Ni . Addition of another 100 PPM of Ni reduced the value to 0.08 meq/g (over 99.5% conversion) . In a second experiment, the wash was carried out in a more conventional way. The cement and aqueous acid were mixed at a high enough stir rate to disperse the acid in the organic phase. After 20 minutes, stirring was discontinued and samples were taken at 15, 30 and 60 minutes. The low lithium and phosphate levels, even after less than an hour of settling, suggest that extraction is efficient and little of the aqueous acid remains entrained after a reasonable settling time. Contact with deionized water resulted in no further decrease in the level of ionic species. After settling - 55 - overnight, the water, lithium and aluminum were down to 330 ppm, 2 ppm, and < 10 ppm, respectively. This sample (107B) was also hydrogenated without difficulty, reaching an residual unsaturation of 0.1 meq/g in 3 hours with only 85 ppm of Ni .

The cements in the above examples were terminated with methanol. Contact with water should also effectively terminate the living chain ends. Since all of the aluminum and lithium are extracted in the wash, the hydrogenation should not be effected by how the polymerization is terminated.

In a third experiment, the "live" polymer cement was added directly to the aqueous acid. Under the mixing conditions of this experiment, a gel formed as the cement was added. The gel formed faster, and was stronger, than was observed in the "minimally - dispersive mixing" experiment. Foaming also occurred, presumably due to out- gassing of ethane. When cements were terminated with methanol, ethane evolution was slower. A significant fraction of the ethane produced by reaction with the alcohol was probably lost when the polymerization reactor was vented. The stir rate was increased to about 400 RPM to facilitate dissolution of the gel. Extraction and de- entrainment was less effective in this case. The final cement contained 780 ppm water, 57 ppm phosphate, 26 ppm Li, and 460 ppm Al . Nevertheless, the hydrogenation was accomplished without difficulty. An residual unsaturation of 0.22 meq/g was achieved after adding only 80 ppm Ni . Table 9. Hydrogenation Results for Alcohol - Terminated and Washed Cements (no pre- ^

O hydrogenation extraction) N_©

SO

Wash Conditions 1^st Catalyst Charge Second Catalyst 3rd Catalyst Charge §

Charge

Phase PPM T_max time RU PPM added time RU PPM added RU

Ratio at at

Run Feed [H3PO4] (Aq.: RPM Ni (°C) (min) (meq/ Ni time (min) (meq/ Ni time time

Organic) g) (min) g) (min) (meq/g)

83A 82D 25 86 60 1.79 125 60 Ϊ20 0.18 ^:Γ AAZ ZZ

!4A 83C^C --- 25 83 60 1.96 125 60 120 0.81 225 V t+60 0.34 as

14C 84B — 25 78 60 4.86 125 60 120 2.86 225 120 180 2.2

90B 90A 50 64 60 9.26 150 60 120 3.01 250 120 180 1.76

104D _{10 c}b -- 100 94 60 6.27 200 60 120 4.5 300 120 225 3.5

n H

W

*<3

NO

NO as.

Table 9 (cont'd). Hydrogenation Results for Alcohol - Terminated and Washed Cements _.

(no pre-hydrogenation extraction) ® NO

>o

Wash Conditions 1^st Catalyst Charge Second Catalyst 3rd Catalyst Charge o

Charge

Phase PPM T_max time RU PPM added time RU PPM added RU

Ratio at at

Run Feed [H3PO4] (Aq.: RPM Ni (°C) (min) (meq/ Ni time (min) (meq/ Ni time time

Organic) g) (min) g) (min) (meq/g)

106A 105B Ϊ0% 0.11 200 50 > 60 2.13 150 60 Ϊ20 0.27 250 Ϊ2^~0 250 0.08

100

1

107C 107B 20% 0.21 400 10 ₁₀3i 30 15.35 35 30 90 0.49 85 90 180 0.1 υj 110A 109B^e 20% 0.21 400 20 90^d 60 5.01 80 60 120 0.22 '

^a sat in autoclave at room temp under H₂ overnight, brought to temp & last 100 PPM added next day.

^•° Initially terminated with 2-ethylhexanol; gelled, added methanol to break. ^c 0.5:1 TEA:Li. d occurred after 2nd catalyst charge. ^e cement washed without MeOH termination. -H

M 3

NO NO δo ON ON -4

Table 10. Results With Use of Pre-Hydrogenation Extraction,

Initial Sample #1 NO NO

[HA] phase moles min .mol . PPM PPM time PPM PPM PPM PPM ϊi

©

Sample add %wt ratio HA HA¹ Li Al (min) RPM water Li AL P (w/w)

105B H3PO4 40% 0.11 0.38 0.38 728 2548 20 100 966 790 6000 31

107B H3P04 20% 0.22 0.40 0.38 728 2548 15 02 - 4 - -

109B

00

13 O

3 13

^Oo δ

OoN ON -J

Table 10 (cont'd) . Results With Use of Pre-Hydrogenation Extraction.

Sample #2 Sample #3 time PPM PPM PPM PPM Time NO

PPM PPM PPM PPM NO ii

©

Sample (min) RPM water Li Al P (min) RPM water Li Al P

105B 20 200 785 194 1100 288 60 200 450 7 45 <10

107B 30 0 - 1 - <5 60 0 2 - <5

109B overni ght 0 780 26 460 20 - - - - - -

¹ For HA = H3PO4, minimum moles of acid = 3.1HA:A1; 1 HA:Li. stirred at 400 RPM for 20', then allowed to settle

3 water washed: 200 g water, 200 RPM, 5', then allowed to settle. O

4 cement was not MeOH terminated; gelled while adding cement tot time stirred 60', max RPM 400.

π ^■d

H

-3

13 v©

NO

©

©

ON ON -4

- 60 -

Example 9

Diol Synthesis Reactions

Polybutadiene diols were prepared as in the experiments reported in Example 8. Synthesis conditions and characterization are described in Table 11.

Unless otherwise specified, the capping reaction was carried out according to procedure (3) of Example 8.

After functionalization and before hydrogenation, the polymer cements were treated with either methanol or a combination of methanol and one of the organic acids listed in Table 11. The acid:polymer and methanol : polymer ratios listed in Table 11 assume quantitative initiation. With the exception of sample 23838-58 and the examples using citric acid, these ratios represent the addition of a total of 8 equivalents of protons per mole of initiator, assuming both phenolic protons of the dihydroxyphenols (catechol, hydroquinone, and 4-t- butylcatechol) are active. That is, enough of either the organic acid or methanol is present to react with the lithium alkoxide chain ends and satisfy all of the valences on the added aluminum.

Sample 23838-58 was initially terminated (neutralized) by adding two equivalents of m-cresol (no methanol) . Hydrogenation performance (discussed in the following section) for this sample was poor, so four equivalents of methanol (for a total of six equivalents of protons per chain) were added during hydrogenation. Citric acid possesses 3 carboxylic acid groups and one hydroxyl per molecule. For the purpose of these calculations, citric acid was assumed to be trifunctional (contribute three equivalents of protons per mole) .

Unless otherwise specified, acids that are solids at room temperature were dissolved in 50 g of diethyl ether and transferred into the reactor from a sample bomb 30 minutes after the EO was added. Methanol was then - 61 -

added from a separate bomb. Due to its low solubility in diethyl ether, citric acid was dissolved in the calculated amount of methanol and both reagents were charged at once. Acids that are liquids at room temperature were added neat and flushed into the reactor with 44 grams of cyclohexane.

The solubility of the salts formed in the termination step varied considerably. No precipitate formed in cements terminated with catechol, 4-t-butylcatechol, or BHT, even after standing at room temperature overnight, while precipitates formed immediately upon addition of 2-ethylhexanoic acid, citric acid, and hydroquinone . Salts of phenol and m-cresol appeared to remain soluble at elevated temperatures. Any precipitate that was formed was re-suspended in the cement prior to transfer to the hydrogenation vessel. In the example in which DEPHA (di-2-ethylhexylphosphoric acid) was used as the terminating agent, 23838-55, the cement gelled on standing overnight However, the addition of 1-2 grams of methanol broke the gel and allowed hydrogenation to proceed.

For comparison, a polymerization was conducted without the addition of an alkyl aluminum reagent at 10% solids, EO was added, and the resulting gel was allowed to stand until the color of the entire reactor contents changed from the red-orange of the polymer anion to the pale yellow of the EO-capped diol. Methanol was added at a ratio of 8 moles per mole of DiLi initiator. The gel broke after standing overnight. -62-

Table 11. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and Capping with EO.

Polymerization Capping Termination o Mn

[DiLi] So(!H Acid: MeOH:

Sample* (N) lids NMR) TEA: Li EO/Li Acid I¹ p2

23838-9 0.48 10% 6190 None 1.4 none 8:1

22930-90A 0.38 10% 5410 1:1³ 2.3 none 8:1

23838-13 0.48 10% 2960 1:1 1.3 BHT⁴ 4:1 4:1

23838-16 0.48 10% 4020 1:1 1.6 TBC⁵ 3:1 2:1

23838-20 0.48 10% 3900 1:1 1.3 TBC⁵ 2:1 41

23838-22 0.48 10% 4170 1:1 1.5 TBC⁵ 1:1 6:1

23838-24 0.48 20% 4270 1:1 1.4 TBC⁵ 1:1 6:1

23838-26 0.48 10% 3940 1:1 1.3 TBC⁵ 0.5:1 7:1

23838-28 0.48 10% 4020 1:1 1.5 phenol 2:1 6:1

23838-30 0.52 10% 4010 1:1 1.4 catechol 1:1 6:1

23838-32 0.52 10% 3620 1:1 1.2 phenol 2:1 6: 1

23838-34 0.52 10% 4620 1:1 1.5 m-cresol 2:1 ' 6:1

23838-36 0.52 10% 3410 1:1 1.2 hydro1:1 6:1 quinone

23838-38 0.52 10% 3760 1:1 1.3 2-EHA⁶ 2:1 6:1

23838-40 0.52 10% 4050 1:1 1.4 2-EHA⁶ 1:1 7:1

23838-43 0.52 10% 4000 1:1 1.4 2-EHA⁶ 3:1 5:1

23838-47 0.50 10% 3740 1:1 1.3 Mix'd 2:1 6:1 cresols^

23838-48 0.57 10% 4650 1:1 1.6 2-EHA⁶ 0.5:1 7.5:1

23838-51 0.57 10% 6030 1:1 2.1 Citric 1:1 5:1 acid - 63 -

Table 11 cont'd. Synthesis Conditions for Preparation of Diinitiated Butadiene Polymers and Capping with EO.

Polymerization Capping Termination o

0 Mn

DiLi] So(^XH Acid: MeOH:

Sample* (N) lids NMR) EO/Li Acid P¹ I²

23838-53 0.42 10^J 4900 1:1 1.5 Citric 0.3:1 7:1 acid

23838-55 0.42 10% 4190 1:1 1.3 DEPHA⁸ 0.5:1 7:l9 23838-58 0.42 10% 3300 1:1 1.2 m-cresol 2:1 4 :1

Iratio of moles of acid to moles of chains (assuming quantitative initiation) .

²ratio of moles of methanol to moles of chains (assuming quantitative initiation) .

^EO and TEA solution pre-mixed then added to polymer anion. This process has also been shown to result in efficient capping 2, 6-Di-t-butyl-4-methylphenol . ⁵4-t-butylcatechol.

62-ethylhexanoic acid.

⁷PMC Specialties Group; 69%-78% m-cresol, 17%-28% phenol, 2%-9% p-cresol.

⁸Di-2-ethylhexylρhosphoric acid. ^Gelled on standing overnight; broke on addition of 1-2 grams methanol.

Hydrogenation

Unless otherwise specified, hydrogenation reactions were carried out in a 1 gal. SS autoclave, using a Ni/Al catalyst prepared by reacting triethylaluminum and nickel octoate (Al:Ni « 2.6:1), according to the following general procedure. The polymer cement was transferred -64- under nitrogen to the autoclave and sparged with hydrogen. The reactor was pressured up to 800 psi with hydrogen. The reactor temperature was adjusted to about 60 °C and then the first aliquot of catalyst solution was added. The autoclave was then heated to maintain a temperature of about 80 °C and reaction was allowed to proceed under 800 psi of H2 for the desired time.

Additional aliquots of catalyst were added as specified in Table 12 below. The extent of hydrogenation was determined using ^H NMR. These results are summarized in Table 12. The goal was to achieve a residual unsaturation (RU) as low as possible.

The final product was isolated as follows. The catalyst was oxidized and extracted with aqueous phosphoric acid (generally 20 %wt) . The ratio of aqueous acid to cement was chosen so as to insure the addition of at least one mole of H3PO4 for every mole of lithium and three moles for every mole of aluminum. Samples for further testing were either washed with deionized water until the pH of the settled aqueous phase was > 5 or washed with concentrated (27 %wt) aqueous ammonium hydroxide and then dried in a rotary evaporator. Table 3 records the concentration of various organic acids in the polymer cement after washing with aqueous acid (catalyst extraction) and then either water or aqueous base.

The addition of organic acids prior to hydrogenation in these examples clearly had a favorable influence on hydrogenation. The residual unsaturation (RU) obtained after each catalyst addition was substantially lower than the example in which only methanol was added following reaction with EO in the presence of one equivalent of TEA (22930-90A) and, in most cases, was lower than or comparable to a control prepared by capping in the absence of trialkylaluminum (23838-9) . -65-

Effectiveness, as judged by improvement in the extent of hydrogenation at a given molar ratio of the organic acid to polymer chains, appears to be a function of both acidity and functionality (acid hydroxyl groups per molecule) . Within the series of acids studied, a higher ratio of mono-hydroxy phenol (phenol, cresol, BHT) to chains (and, therefore, to lithium and aluminum) appears to be required to achieve a comparable improvement in hydrogenation than if a di-hydroxy phenol (hydroquinone, catechol, TBC) is used. Final RU levels comparable to those obtained in the presence of 2 moles of mono- hydroxy phenol (2 protons from the acid per chain) could be obtained by the addition of 1 equivalent of a di- hydroxy phenol. This observation provides evidence that both phenolic groups are active in the latter.

Carboxylic acids appear to be more effective than di- hydroxy phenols, especially when considered on an equivalent basis, i.e. at the same ratio of protons fr-'-m the acid per chain. The addition of one equivalent -H+ per chain from 2-EHA (23838-41) resulted in a lower RU at a given catalyst level than the addition of one equivalent H+ per chain from TBC (23838-27) . At the higher levels of 2-EHA, emulsion problems were encountered when the cement was contacted with aqueous acid (at a relatively high shear rate) to extract the nickel and aluminum. While the problem could be mitigated by washing at a lower shear rate, it is preferable to keep the 2-EHA:P ratio less than 2:1. The addition of one mole of citric acid per mole of polymer led to rather poor hydrogenation performance. The viscosity increased substantially during the hydrogenation. The addition of this much of a highly functional acid may lead to aggregation of the catalyst. However, excellent performance was observed when the ratio of citric acid to chains was decreased to 0.3 (one acidic proton per chain) . DEPHA, the strongest acid - 66 -

studied, was most effective on a molar equivalents of protons basis. At 0.5 moles DEPHA (also 0.5 moles H+) per chain, a final RU of 0.11 meq/g was obtained. This is comparable to results obtained at twice the H+ added as 2-EHA or citric acid.

In all of the above examples, it was assumed that the presence of aluminum alkyl (Al-R) groups was deleterious to hydrogenation. A sufficient quantity of hydroxyl or acid functionality was provided to convert all of the Al-R bonds to Al-OR bonds. Run 23838-58 was carried out in order to determine if neutralization of the lithium alone was sufficient to ensure facile hydrogenation. When the cement was terminated with 2 moles (1 per Li) of m-cresol per mole of polymer (1 equivalent of phenolic protons per equivalent of lithium) and contacted with

50 ppm of Ni catalyst, a very weak exotherm was observed. This was taken to indicate very little hydrogenation, as exotherms in excess of 15 °C were observed in the previous examples. Sufficient methanol was then added tc account for 2/3 of the expected Al-R groups. This resulted in a significant exotherm. The results summarized in Table 2 indicate that hydrogenation was efficient under these conditions, but the cement became quite viscous to the point of being difficult to transfer from the autoclave. Based on this observation, it is reasonable to conclude that it is preferable to add one equivalent of hydroxyl or acid protons per lithium and 3 equivalents of hydroxyl or acid protons per aluminum. While low levels of the acids studied are generally expected to be tolerable in the final product, for some applications it may be desirable to remove the majority of the acid from the hydrogenated polymer. Table 3 summarizes some work done to determine how this is best accomplished. Although most of the phenols are soluble in water, contact with aqueous acid or deionized water - 67 - could not be shown to quantitatively extract the phenol. While the extraction of catechol into water in run 31 looked promising, attempts to reproduce this result were inconclusive. Extraction into aqueous base was more efficient, but phenols are known to oxidize to strongly colored products, especially in the presence of base. All of the cements containing phenols contacted with aqueous base were colored. Likewise, the cement containing hydroquinone became strongly colored after contact with water. The low level of hydroquinone in the cement following contact with water may be a result of degradation rather than extraction. Carboxylic acids are expected to be readily extracted into aqueous base without forming colored products. Run 48 supports this conclusion. If a phenol is used to improve hydrogenation, these results suggest that it is best to chose a relatively volatile one and avoid oxygen and base during the devolatilization. Carboxylic acid-modified cements are preferably extracted with aqueous base.

Table 12. Summary of Hydrogenation Results for Phenol & Acid - Terminated Cements

1st Catalyst 2nd Catalyst Charge 3rd Catalyst Charge

N ;Oo Charge ©

PPM Tmax time RU PPM added time RU PPM added time RU

Run Feed termin ROH Ni (°C) (min) (meq/ Ni at (min) (meq/ Ni at (min) (meq/ q ⁾ time g ⁾ Time g ⁾ (min) (min)

10 9 MeOH 50 74 60 2.43 150 60 120 1 250 120 180 0.49

90B 90A MeOH 50 64 60 9.26 150 60 120 3.01 250 120 180 1.76

14 13 4 BHT¹ 50 74 60 2.88 150 60 120 0.78 250 120 180 0.29

17 16 3 TBC¹ 50 83 60 0.51 150 60 120 0.1 250 120 180 0.06 σs

21 20 2 TBC¹ 50 65 60 0.17 150 60 120 0.05 250 120 180 0.08 oo

23 22 1 TBC¹ 50 85 60 0.63 150 60 120 0.14 250 120 180 0.11

25 24 1 TBC¹ 50 148 60 1.46 150 60 120 0.22 250 120 180 0.14

27 26 0.5 TBC¹ 50 85 60 1.23 150 60 120 0.49 250 120 180 0.23

29 28 2 PhOH¹ 50 72 60 2.93 150 60 120 1.24 250 120 180 0.33

31 30 lCatechol¹ 50 88 60 0.61 150 60 120 0.14 250 120 180 0.18

33 32 -β

2 PhOH¹ 50 80 60 1.91 150 60 120 0.77 250 120 180 0.31 O H

35 34 2 m-cresol¹ 50 86 60 1.48 150 60 120 0.61 250 120 180 0.26 P9

13 o o

37 36 lhyQ¹ 50 90 60 0.59 150 60 120 0.18 250 120 180 0.11 © ©

ON ON -J

Table 12 Summary of Hydrogenation Results for Phenol & Acid - Terminated Cements (Cont'd)

1st Catalyst 2nd Catalyst Charge 3rd Catalyst Charge Charge NO O ii

PPM Tma time RU PPM added time RU PPM added time RU ©

Run Feed termin ROH Ni (°C) (min) (meq/ Ni at (min) (meq/ Ni at (min) (meq/ g⁾ time g⁾ Time g⁾ (min) (min)

39 38 2 2EHA¹ 50 100 60 0.83 150 60 120 0.14 250 120 180 0.09

41 40 1 2EHA¹ 50 79 60 1.42 150 60 120 0.37 250 120 180 0.16

44 43 3 2EHA¹ 50 99 60 0.41 150 60 120 0.15 250 120 180 0.07

45 47 2 mix'd 50 78 60 1.94 150 60 120 0.86 250 120 180 0.43

NO cresol¹ < ⁴

49 48 0.5 2EHA¹ 50 70 60 4.52 150 60 120 1.4 250 120 180 0.74

50 51 1 citric 50 70 60 4.28 150 60 120 3.19 250 120 180 2.47 acid¹' ²

54 53 0.3 citric 50 85 60 1.3 150 60 120 0.4 250 120 180 0.14 acid

56 55 0.5 DEPHA¹'² 50 61 60 1.26 150 60 120 0.21 250 120 180 0.11

1

59 58 2 m-cresol, 4 50 81^J 60 0.15 150 60 120 0.07 250 120 180 0.06 π3

MeOH 13 NO O as as

-70- moles per mole of chain; unless otherwise specified, MeOH added so total OH:polymer = 8 (1 per Li, 3 per Al) .

² gelled on standing overnight; broke with 1-2 g. MeOH.

3 5°C initial exotherm in the absence of methanol; maximum temperature after adding 4 equivalents of methanol .

⁴ assume 73% m-cresol, 22% phenol, 5% p-cresol.

Table 13. Distribution of 0rganic Acid Modifiers Following Wash & Devolatilization Wash#l Wash#2

O

Termipred pred % ArO] g

' — nating [ArOH] [ArOH] condi[ArOH] O condi[ArOH] % [ArOH] Over- S sample Agent cement neat tions cement extr ' d tions cement extr'd PPM head

2 255 TTBBCC 0 0..9933%% 4 4..6600%-^c 30% 0.87% 6% DIW 0.81% 12.90% 28000 27 . 17 ^s

H3PO4

3 311 ccaattee¬0 0..3311%^! 3 3..0077%. 20% 0.13% 58% D DIIWW 00..0044%% 8877..1100%% 22550000 4 . 8 9⁵ cchhooll H3PO4

3 333 pphheennooll 0 0..5533%^! D 5 •. -2O5 ^*^5 20% 0.06% 89% 2 277%% 0 0..0022%% 9 966..2233%% 6 60000 2.67%

H3PO4 N NHH44OOHH 1

^1

35 m- 0.61% 6.04% 20% 0.24% 61% 2277%% 0 0..1111%% 8 811..9977%% 5 5000000 9.93% ^"ϊ^* ccrreessooll H3PO4 N NHH44OOHH

3 377 hhyyddrroo-0 0..3311%⁵ 3 3..0077%? 20% 0.002% 99% D DIIWW 0 0..0000%% 9 999..6688%% < < 5500 0.00% qquuii-H3PO4 none

48 2 -EHA 0 . 2 % 2 . 0 % 20 % 27 % 209 H3 PO4 NH4 OH

13 π

U δ

Claims

-72-C L A I M S

1. A process for making gel-free functionalized anionic polymers using multi-alkali metal initiators which comprises : anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, capping the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly associating chain ends are formed wherein a strongly associating gel is formed, and adding a trialkyl aluminum compound to the gel.

2. A gel-free process for making functionalized anionic polymers using multi-alkali metal initiators which comprises : anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, adding a trialkylaluminum compound before or during polymerization or before or at the same time as the capping agent, and capping the polymer by adding to the polymer a capping agent which, in the absence of the trialkylaluminum compound, would react with the polymer chain ends to form strongly associating chain ends wherein a strongly associating gel would be formed.

3. The process of claim 1 or 2, wherein the initiator is a dilithium initiator.

4. The process of claim 3 wherein the initiator is formed by reaction of an organolithium compound, with a compound selected from the group consisting of diiso- propenyl benzene, diphenylethylene, styrene, butadiene, isoprene, 1, 3-bis ( 1-phenylethenyl) benzene and derivatives - 73 -

thereof, and 1 , 4-bis ( 1-phenylethenyl ) benzene and derivatives thereof.

5. A process for making a gel-free functionalized polymer from an unfunctionalized polymer which comprises: reacting the unfunctionalized polymer with an alkali metal alkyl in the presence of a promoter, reacting the alkali-metal-containing polymer with a capping agent that reacts with the alkali-metal- containing sites on the polymer such that strongly associating chain sites are formed wherein a strongly associating gel is formed, and adding a trialkylaluminum compound to the gel.

6. A gel-free process for making a functionalized polymer from an unfunctionalized polymer which comprises: reacting the unfunctionalized polymer with an alkali metal alkyl in the presence of a promoter, adding a trialkylaluminum compound before addition of the capping agent or at the same time as the capping agent, and reacting the alkali-metal-containing sites on the polymer with a capping agent which, in the absence of the trialkylaluminum compound, would react with the alkali metal-containing sites to form strongly associating chain sites wherein a strongly associating gel would be formed.

7. The process as claimed in claim 5 or 6, wherein the alkali metal is lithium.

8. A process for making gel-free functionalized polymers from polymers which are already functionalized with functionality that forms strongly associating chain sites when reacted with alkali metal reagents, thereby forming a strongly associating gel, said process comprising: reacting said already functionalized polymer with an alkali metal reagent to form a strongly associating gel, and -74- adding a trialkylaluminum compound to the gel.

9. A gel-free process for making functionalized polymers from polymers which are already functionalized with functionality that forms strongly associating chain sites when reacted with alkali metal reagents, thereby forming a strongly associating gel, said process comprising: adding a trialkylaluminum compound to the already functionalized polymer, and subsequently reacting said already functionalized polymer with an alkali metal reagent.

10. The process as claimed in any one of the preceding claims, wherein the alkyl groups in the trialkyl aluminum compound contain from 1 to 10 carbon atoms.

11. The process as claimed in any one of the preceding claims wherein the molar ratio of the trialkylaluminum compound to the chain ends is at least 0.1:1.

12. The process of claim 8 or 9 wherein the alkali metal reagent is selected from the group consisting of lithiur hydride, lithium alkyl, sodium hydride, sodium alkyl, potassium hydride, and potassium alkyl.

13. The process as claimed in any one of the preceding claims which comprises the further step of hydrogenating the polymer with a hydrogenation catalyst.

14. The process as claimed in claim 13, wherein the polymer is washed with aqueous acid prior to the hydrogenation step but after polymerising and capping of the polymer, and optionally terminating the capped polymer with a terminating agent, or after reacting of the functionalised polymer with an alkali metal reagent, and after adding of the trialkylaluminum compound.

15. The process of claims 13 or 14 wherein the acid is a mineral acid.

16. The process of claim 15 wherein the mineral acid is phosphoric acid wherein there is at least one mole of - 75 -

phosphoric acid per mole of alkali metal and at least three moles of phosphoric acid per mole of aluminum.

17. The process of claim 15 or 16 wherein the concentration of the acid is from 20 to 40 percent by weight and the phase weight ratio of aqueous acid to polymer plus solvent is from 0.1:1 to 0.25:1.

18. The process as claimed in claim 12, wherein prior to the hydrogenation step, a proton source is added to the trialkylaluminum compound-containing solution of capped polymer, which proton source is added in a sufficient amount to provide at least 1 mole of protons per mole of alkali metal ions and at least 2 moles of protons per mole of aluminum wherein the proton source is an organic acid with a pKa of 11 or less or a mixture of the organic acid and an alkanol having a pKa of more than 11, provided that sufficient organic acid is added to provide at least 0.4 moles of protons per mole of alkali metal ions .

19. The process of claim 18 wherein the organic acid is selected from the group consisting of carboxylic acids, aromatic alcohols, and mineral acid esters.

20. The process of claim 19 wherein the organic acid is selected from the group consisting of phenol, catechol, 4-t-butylcatechol, m-cresol, p-cresol, 2, 6-di-t-butyl-4- methylphenol, citric acid, 2-ethylhexanoic acid, di-2- ethylhexylphosphoric acid, hydroquinone, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, steric acid, and mono-2- ethylhexylphosphoric acid.

21. The process of any one of claims 18 to 20 wherein the sufficient organic acid is added to provide from 0.5 to 1 moles of protons per mole of alkali metal ions.

22. The process of any one of claims 18 to 21 wherein a sufficient amount of the proton source is added to provide at least 3 moles of protons per mole of aluminum. - 7 6 -

23. The process of any one of claims 18 to 22 wherein the concentration of the acid is from 20 to 40 percent by weight and the phase weight ratio of acid to polymer cement of from 0.1:1 to 0.25:1.

24. The process of any one of claims 18 to 22, wherein the capped polymer is polymerised with a multilithium initiator .