CA1116345A - Copolymers of cyclic organic monomers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
There are disclosed hydroxyl terminated copolymers of (a) at least one cyclic organic monomer which polymerizes with an active hydrogen initiator to form primary hydroxyl terminal groups and (b) at least one cyclic organic monomer which polymerizes with an active hydrogen initiator to form secondary hydroxyl terminal groups, said copolymer having a ratio of primary to secondary hydroxyl terminal groups which is controlled independently of overall copolymer chain structure.

Description

~ ~ 6 3 ~ ~ 10,830 BACKGROUND OF THE INVENTION
Copolymers produced by ~he ring-opening addition copolymerization o~ at least two different cyclic organic monomers, such as ethylene oxide, propylene oxide, styrene oxide or tetrahydrofuran, are well known and include compounds having a broad range of chemical and physical properties and end uses.
Generally, the ring-opening addition copolymeriza~ion is initiated by any of the well known active hydrogen I0 contai~ing initiators which include alcohols, amines, thiols, carboxylic acids or the corresponding di- or trifunctional initiators and the polymerization can be acid-catalyzed or base-catalyzed. The ring-opened `i addition copolymer thus produced has one or more tenm-inal hydroxyl groups in accordance with the function-., ality of the initiator. Since the terminal hydroxyl groups are highly reactive~ these copolymers are useful as intermediates in the production of many commercially important classes of compounds including polyesters, polyurethanes, polyacetals, polysiloxanes, polyethers ~ and polycarbonates.
`~ Each terminal hydroxyl group of the ring-;~ opened addition copolymer can be a primary or secondary hydroxyl group, depending on the nature of the mer unit to which the terminal hydroxyl group is bonded. Those skilled in the art will recognize that during the ~a ~,',. ~

~ 10,830 polymerization certain cyclic organic mon~mers, such as ethylene oxide and tetrahydrofuran, undergo ring-opening addition to the polymer chain in such a way as to form primary hydroxyl terminal groups in most instances (hereafter referred to as "primary hydroxyl forming monomers"), while other cyclic organic monomers undergo ring-opening addition to the polymer chain in such a way as to form secondary hydroxyl terminal groups in most instances (hereafter referred to as "secondary hydroxyl forming monomers"). Thus, for example, a copolymer of ` ethylene oxide (a primary hydroxyl forming monomer) and propylene oxide (a secondary hydroxyl forming monomer) has primary hydroxyl terminal groups at most of the sites at which the last mer unit added to the polymer chain is `~ an ethylene oxide derived mer unit and secondary hydroxyl terminal groups at most of the sites at which ~he last mer unit added to the polymer chain is a propylene oxide derived mer unit.
In copolymerizing one or more cyclic organic monomer~ of the primary hydroxyl forming type (e.g., ethylene oxide) and one or more cyclic organic monomers of the secondary hydroxyl forming type (e.g., propylene oxide) it is highly desirable to be able to control tha ratio o primary to secondary hydroxyl terminal groups in the resultant copolymer. Since primary hydroxyl groups are more highly reactive than secondary hydroxyl ~' ~ 10,830 groups, this ratio affec~s the rate of reaction of the copolymer with other reactive compounds. While it is requently desired to maximize the rate of reaction of the copolymer with other reactive compounds for economic reasons, one may also desire to react the copolymer with another compound at a relatively slow controlled rate of reaction. For example, in reacting the ring-opened addition copolymer with an isocyanato compound to produce - a polyurethane resin, one may desire a slow reaction rate to increase the pot life of the resin. Moreover, the ratio of primary to secondary hydroxyl terminal groups affects the distribution of reaction products in certain reactions of the copolymer such as, for example the distribution of ketones and aldehydes which are obtained upon oxidation of the terminal hydroxyL groups of the copolymer.
In the prior art, copolymers produced by the rin~-opening addition copolymerization of one or more ; cyclic organic monomers of the primary hydroxyl forming type and one or more cyclic organic monomers of the secondary hydroxyl forming type ~hereafter called "mixed hydroxyl end group copolymers") have offered little control over the ratio of primary to secondary hydroxyl terminal groups. Mixed hydroxyl end group copolymers produced by conventional block copolymerization are terminated predominantly by pr~mary hydroxyl groups or ~ 63~ lo,830 .~

predominantly by secondary hydroxyl groups, depending on whether the last monomer fed to the polymerization reactor is of the primary or secondary hydroxyl forming type, Mixed hydroxyl end group copolymers produced by conventional random copolymerization have a ratio of primary to secondary hydroxyl end groups which is sub-stantially fixed for any given ratio o primary to secondary hydroxyl forming monomers in the feed stream.
Thus, it can be seen that the ratio of primary to secondary hydroxyl terminal groups in mi~ed hydroxyl end groups copolymers produced by these methods is dependent on the overall structure of the copolymer chain. This is undesirable since it may preclude the skilled worker in the art from producing a mixed hyd-roxyl end group copolymer havLng both the optimum ratio of primary to secondary hydroxyl terminal groups and the optimum overall copolymer chain structure ~or a partic-ular end use. Those skilled in the art will recognize that the overall chain structure affects important properties of the copolymer such as surface acti~ity and viscosity. For example, block copoly~er of ethyl-ene oxide and propylene oxide generally have high surface activity due to homogeneity within the hydro-phobe block (propylene oxide block) and hydrophile block (ethylene oxide block), while random copolymers of _ ~' 10,830 ethylene oxide and propylene oxide lack the pronounced surface active characteriscics of their blocked count-erparts. Heretofore, there have not been available mixed hydroxyl end group copolymers having ratios of primary to secondary hydroxyl terminal groups which can be varied independently of the overall copolymer chain structure.
SUMMARY OF THE INVENTION
The present invention provides mixed hyd-roxyl end group copolymers having a controlled ratio of primary to secondary terminal hydroxyl groups, said ratio being independent of the overall monomer sequence distribution in the copolymer chain. As a consequence, the copolymers of this invention exhibit properties not heretofore attalnable in mixed hydroxyl end group copolymers. The process used to produce the novel copolymers of this lnvention is essentially that dis-closed in U.S. 3,804,881. However, the copolymers vf this invention are not disclosed therein and are not known in the prior art.

The single figure is a schematic illustration of an apparatus suitable for the preparation of the novel compounds of this invention by the process described herein.

3 ~ ~
10,830 DESCRIPTION OF THE INVENT_ION
The novel copolymers of the present invention are produced from at least two cyclic organic monomers capable of undergoing ring-opening addition copolymer-ization with an active hydrogen containing initiator.
At least one of the cyclic organic monomers is one which undergoes ring-opening addition to the polymer chain in such a way as to form a primary hydroxyl terminal group and at least one of the cyclic organic monomers is one which undergoes ring-opening addition to the polymer chain in such a way as to form a secondary hydroxyl terminal group. Typically, the primary hydroxyl forming monomer can be ethylene oxide or tetrahydrofuran and the - secondary hydroxyl forming monomer is a 1,2-epoxide oth~r than ethylene oxide; including propylene oxide, butylene oxide, styrene oxide, cyclohexene oxide, 1,2-epoxy-butadiene, 3-phenoxy-1,2-propylene oxide, glycidyl acrylate, 1,2-epoxy-4,4,4~trichlorobutane, 1,2-epoxy-cyclohe~ene, 5,6 epoxy-2-norbornene, glycidyl metha-crylate, epichlorohydrin, cyclohex-3-eny-1,2-epoxy-ethane, linseed oil epoxide, 1,2-epoxytetradecane and the like. Additionally, other classes of cylic organic ; monomers can be used to produce the novel copolymers of the present invention, provided that they undergo - ring-opening addition polymerization with an active hydrogen containing initiator to form terminal hydroxyl ~ 10,830 groups. Exæmples of other suitable classes are the lactones, such as ~-propiolactone, epsilon-caprolactone, and valerolactone~ oxazoLidine-2,5-diones such as glycine N-carboxyanhydride and the lactides. Those skilled in the art will know which of the suitable cyclic organic monomers undergo ring-opening addition to the polymer chain to form primary hydroxyl terminal groups and which undergo ri.ng-opening addition to the polymer chain to form sec(~nda_y hydroxyl terminal groups. The onLy limitations on the combinations of primary and secondary hydroxyl forming monomers which can be suitaDly employed is that the ca~alyst system used must be active for all types of monomers used and that the reaction conditions employed must be otherwise compatible with the chemistries o~ the respective monomers.
The process for producing the novel polymers of this invention includes at least one stage which comprises the steps of introducing at least one main .
;~ 20 polymerizable ~eed cGmposition comprising at least one .
of the cyclic organic monomers capable of ring-opening addition polymerization from at least one main f~ed .
source to a polymerization zone, the main polymerizable ~ feed composition varying in compositional content of the .'''~

~ 10,830 polymerizable monomers therein during the continuous introduction; simultaneously adding to the main feed source at least one different auxiliary polymerizable feed composition comprising at least one of the cyclic organic monomers capable of ring-opening addition polymerization from at least one auxiliary feed source so as to continually change the compositional content of the polymerizable monomers in the main polymerizable feed composition; and continuously polymerizing the main polymerizable feed com~osition introduced to the polymerization zone until the desired polymerization has been achieved. Initially, the primary hydro~yl forming monomer or monomers and the secondary hydroxyl forming monomer or monomers can be present in either the main or auxiliary feed compositions in any concen-tration desired, subject only to the restriction that the concentrations of primary hydroxyl forming monomers and secondary hydroxyl forming monomers initialLy present in the main ~eed composition are different from the concentrations of primary hydroxyl forming monomers and secondary hydroxyl forming monomers in the auxiliary eed compositionsO Due to the difference in reactivi-~ies of the primary hydroxyl forming monomers and secondary hydroxyl fo-rming monomers, it is essential to maintain conditions in the polymerization zone approaching monomer starvation so that the composition 10,830 of the polymer chain being formed at any instant closely resembles the main feed composition being fed to the polymerization zone.
It can be readily appreciated that the present invention permits the skilled woker to care-fully control the compositional content of mer units derived from primary hydro~yl forming monomers and mer u~its derived from secondary hydroxyl forming monomers along the entire length of the polymer chain. By con~rolling the compositional content of mer units at the terminal portion of the polymer chain, the skilled worker thereby controls the ratio of primary to second-ary terminal hydroxyl groups. Moreover, by the proper choice of compositional con~en~s and feed rates of the main and auxiliary feed sources, which will be appar-.~
.
ent to the skilled worker from the disclosure herein, the ratio of primary to secondary hydroxyl terminal groups can be varied independently of the composîtional ~ .
content of the rest of the polymer chain.
The novel polymers of this invention can, ~; therefore, have any of an unlimited number of combi-nations of chain structures and ratios of primary to secondary hydroxyl terminal groups. For example, one can ha~e a polymer in which the ma~or portion of the polymer chain consists of alternating blocks of mer units derived from primary hydroxyl forming monomers and mer units derived from secondary hydroxyl forming monomers ""~' ' 10--~ 5 10,830 and the terminal portion contains 50% primary hydroxyl groups and 50% secondary hydroxyl groups. One can also have a polymer in which the major portion of the polymer chain consists of a uniformly random structure having 80~ mer units derived from secondary hydroxyl forming monomers and 20% mer units derived from primary hydroxyl forming monomers and the terminal portion contains 95% primary hydroxyl groups and 5% secondary hydroxyl groups. One can also have a polymer in which the major portion of the chain length is a random arrangement of mer units derived from primary hydroxyl forming monomers and mer units derived from secondary hydroxyl forming monomers, in which the ratio of the two types of mer units varies continuously along the chain length as desired, and the terminal portion con-tains an~ desired ratio of primary hydroxyl groups to secondary hydroxyl groups. Alternatively, one can have a polymer in which the major portion of the polymer chain contains a series of segments, each of which can have any of the aforementioned block or random mer unit arrangements, the segments being arranged in any desired order, and the terminal portion contains any desired ratio of primary hydroxyl groups to secondary hydroxyl groups. The above examples are intended to be only illustrative of the unlimited number of obtain-able structures and are not meant to limit the scope of the invention.

10,830 The process described above allows the poly-merization scientist to control the polymerization process in such a manner that he can produce polymers ha~ing any combination of (a) properties which are dependent on the ratio of primary to secondary hydroxyl groups (e.g., reactivity) and (b) properties which are dependent on overall chain structure (e.g., surface activity and state of aggregation). The polymers are produced ~y a process in which the concentrations of primary hydroxyl forming monomers and secondary hydroxyl forming monomers in the main polymerizable feed composi~ion are continually changing d~ring the introduction of the main polymerizable ~eed mixture to the polymerization zone by the sim~ltaneous addition of a different auxiliary polymerlzable cyclic orgaQic monomer feed mi~ture to the main polymerizable feed mixture. The ratio of primary hydroxyl terminal groups to secondary hydroxyl end groups is determined by the conce~trations o primary hydroxyl orming monomers and secondary hydroxyl forming monomers in the main polymerizable feed mixture during the ormation of the terminal portions of the polymer chains. By continually varying ~he composition of the main poly-merizable feed mixture throughout the polymerization one can obtain previously unobtainable combin~tions of overall chain structure and ratio of primary hydroxyl .

~ 3~ ~ 5 lG,830 terminal groups to secondary hydroxyl terminal groups.
The distinguishing feature of the process is the intro-duction of a main polymerizable monomer feed composition to the polymerization zone from a maln feed source while simultaneously introducing at least one auxiliary poly-merizable feed composition having a different concentra-~ion of primary hydroxyl forming monomers and secondary hydroxyl formlng monomers to the main polymerizable feed composition in the main feed source.
The polymerization zone is any reactor, prop-erly equipped, that can be used for the production of polymers. The different types of reactors and their suitability for a particular polymeri~ation reaction , .
are well known to those skilled in the art and do not require elaboration herein. Connecting to the polymer-ization reactor is at least one main feed source. The term "main feed source" defines one or more tanks or sources of cyclic organic monomers feeding directly into the polymerization zone or reactor, for example, it can be an in-line mixer or a tank. The main eed source is equipped with efficien~ mixing means to assure adequate mixing of the contents thereof. Connecting, in turn, to any of the main feed sources is at least one auxili-ary feed source. The term "au~iliary feed source" defines one or more tanks or sources of cyclic organic monomers feeding to any of the main feed sources. There can be ~ 10,830 one or more auxiliary feed sources with all of the auxiliary feed sources feeding directly into the main feed source, or one or more of ~he ~uxiliary feed sources can ~eed in series to another auxiliary feed source and be thoroughly mixed therein with finally an ultimate auxiliary feed source feedLng directly into one or more of the main feed sources. The ra~e of feed rom any one feed source or tank to any other fecd source or tank, whether a main feed source or an auxiliary feed source, can be varied at the will of the skilled scientist to obtain the desired ratio of primary to secondary hydroxyl terminal groups. The -`~ configurations that can be engineered are many;
however, in all instances there must be a polymerization zone or reactor connected ~o at least one main feed source or tank equipped with mixing means which in turn is connected to at least one auxiliary feed source or tank which auxiliary feed sources twhen more than one thereof is used) can all or in part feed directly into one or more of the main feed sources or tanks or can ~eed in series into one another and ultimately feed into the main feed source or tank.
The main polymerizable feed composition is the mixture of reactants present at any particular time in the main feed source or tank. This mixture can contain the cyclic organic monomers alone or it 3f~5 lo, 830 can include any additive which will not have a deleterious effect on the cyclic organic monomers, for example, diluents or solvents, colorants, dispersion or emulsion agents, anti-oxidan1-s, stabilizers, chain transfer agents, crosslinkers, initiators, one of the components of a redox catalyst system~ and the like.
The compositional content of the main polymeri~able feed composition is continually changing as auxiliary polymerizable feed composition is fed into and mixed with it. By the term compositional content is meant the content or concentration in the polymerizable feed composition of each reactant therein. As becomes apparent from this teaching and description the simul-taneous feeding of the main polymerizable feed compo-sition from the main feed source ta the poly.merization zone and feeding o~ a diferent polymerizable fe~d composition rom the auxiliary feed source to the main feed source will result in a continual change of the content or concentration of each reactant present in the main polymerizable feed composition or in the compositional content of the main polymerizable feed composition. This continual change in compositional content can also occur in the auxiliary polymerizable feed compositions when more than one thereof is being used and they are feeding in series into each other before ultimately feeding into the main polymerizable 10,830 feed composition. It is the continual change in the relative concentrations of pr~mary hydroxyl forming ~ monomers and secondary hydroxyl forming monomers in the ; main polymerizable feed composition during the forma-tion of the terminal portions of the polymer chains which allows the ratio of pr:mary to secondary hydroxyl terminal groups to be controlled independently of over-all polymer chain structure.
`~ The auxiliary polymerizable feed composition `~ 10 is the mixture of reactants present at any particular time in any one or more of the auxiliary feed sources or tanks and can contain the same types o additives ; tha~ were previously indicated could be present in the main polymerizable feed composition. It should be remembered, however~ that if one of the polymerizable feed mixtures contains one of the components of a catalyst system that the other such mixtur~ cannot contain the other component thereof, otherwise polymer-ization will orcur in the feed tanks before the poly-merizable reactants are introduced into the~polymer-izatio~ zone.
As indicated, in the process of this invention there are used main poLymerizable feed compositions and auxiliary polymerizable feed compositions. The main polymerizable feed c~mposition can initially contain a single polymerizable cyclic organic mo~omer or it can initially contain a plurality of polymerizable ~ 3 ~ ~ 10,830 cyclic organic monomPrs; the same is true for the auxiliary polymerizable feed composition. However, when the main polymerizable feed composition is a single reactant the auxiliary polymerizable feed composition cannot be solely that same single reactant, it can be a different single reactant or a mixture of a plurality of reactants that can include that same reactant in the mixture. Likewise, when the main polymerizable feed composition is a mixture of a plurality of reactants the auxiliary polymerizable feed composition cannot be that same mixture having the same concentrations ~or each reactant; it can be a different mixture of reactants or it can be a mixture of the same reactants but at different initial concentra~ions of the react-ants. In all instances, at lea.st one of the polymer-izable ~eed compositions must contain a cyclic organic monomer of the primary hydroxyl forming type and at least one of the poly~erizable feed compositions must contain a cyclic organic monomer of the secondary hydroxyl forming type. Moreover, an important and ever present factor is that the initial compositional ~on-tents of the main polymerizable feed composition and of the auxiliary polymerizable feed composition are always different, they are not initially identical in make-up of polymerizable reactants.

~ ,830 As a result o~ the initial differences in the compositional contents of the main and auxiliary poly-merizable feed compositions and of the simultaneous addition of auxiliary polymerizable feed compositions and of the simultaneous addition of auxiliary polymer-izable feed composition to the main polymerizable feed composition while the main polymerizable feed - composition is introduced into the polymerization zone there is a continual variation in the compositional content of the main polymerizable feed composition.
Hence, any portion of the main polymerizable feed composition entering the polymerization zone is at all times different than the portion which preceded it and the portion that succeeds it. Consequently~ the composition of the polymer produced in the reactor during the addition is likewise continuously changing and reflects the composition of the main polymerizable feed composition entering the polymerization zone. In a rapid polymerization reaction, one wherein there is essentially instantaneous reaction of the monomers when they are introduced to the polymerization zone, one has what is known as a monomer starved system. In other reactions one may have a so-called monomer rich system, i.e., a system in which there is some delay between introduction of the rea~tants to the polymer-ization zone and essentially complete pslymeriza~ion ~ 3~ ~ 10,~30 -of the reactants. Thus, in a monomer starved system the poLymer produced at any one period of time differs in constitutlonal content from the polymer produced prior to that period of time or subsequent to that period of time. By employing a monomers starved system and the aforementioned means of continuously varying the compositionaL content of the polymerizable feed composition, one can produce a polymer which has a terminal portion having a molecular structure which is entirely independent of the structure of the remainder of the polymer chain The process used to produce the novel polymers of the present învention can be described in its simp-lest manner by a reaction involving a single main feed source initially containing a single primary hydroxyl forming monomer ~or secondary hydroxyl forming monomer) and a single auxiliary feed source initially containing a single secondary hydroxyl forming monomer (or primary hydro~yl forming monomer, when the main feed source ~`~ ; 20 con~ains a secondary hydroxyl forming monomer). The contents in the main feed source or tankat any time during the process are known as the main polymerizable feed c~mposition and the contents of the auxiliary feed source or tank are known as the auxiliary polymerizable feed c~mposition. The auxiliary feed source feeds into the main feed source by suita~le lines and pumps; the ~ 10,830 main feed source is equipped with an effieient stirrer or mixer and feeds into the polymerization zone. At the start o the polymerization reaction the flow of the main primary feed composition from the main feed source to the polymerization zone is commenced at a predetermined rate, simultaneously the flow of auxiliary polymerizable feed composition from the auxiliary feed source to the main feed source is initiated and this rate of flow can be the same as or different from the rate o~ flow from the main feed source to the polymer-ization zone. As the auxiliary polymerizable feed comp-osition enters the main feed source it is thoroughly mixed with the contents thereof resulting in a continual change in the compositional content of the main poLymer-; izable feed composition. This continually changing main polymerizable feed composition is simultaneously and continuously entering the polymerization zone. As is apparent from the prior descrlption either or both of the main or ~uxiliary feed source can contain more than one polymerizable reactant.
The variations in the engineering arrange-ments of the main and auxiliary feed sources are innumerable and no attempt will be made to set forth each specific tank configuration or arrangement pos-sible; these can readily be devised by skilled individuals at wiLl for the purpose of obtaining ~ 3~ 10,330 products having certain desired properties. In the preceding paragraph there has been outlined a simple arrangement employing a single maîn feed source and a single auxiliary feed source. Slightly more complex arrangements would be those wherein there was a single main feed source and a plurality of auxiliary feed sources; in these instances all of the auxiliary feed sources could be feeding in parallel directly into the main feed source or some of the auxiliary feed sources could be feeding in series to other auxiliary feed sources with at least one auxiliary feed source, whether in series or not, ultimately eeding directly into the main feed source. Other arrangements would be those wherein there were a plurality of main feed sources;
in these instances there could ~e a single auxiliary feed source feeding into one or more o the plurality of the main feed sources3 or there could be a plurality of auxiliary eed sources all feeding in parallel directly into only one of the main feed sources, or a plurality of auxiliary feed sources directly feeding into more than one main feed source or all of the plurality of auxiliary feed sources could be feeding -~ in series into only one of the main feed sources, or the plurality of auxiliary feed sources can be feeding in series into more than one of the main feed sources.
When a plurality of auxiliary feed sources is used ~ ~63~ 83~

they can be used in any combination desired, all can be used in series, some can be used in series while others are not, or none need be used in series wi~h all of them being added dixectly to the main feed source. In all instances the main feed sources eed the main polymer-izable feed composition to the polymPriza~ion zone;
the auxiliary feed sources feed the auxiliary polymer-izable feed composition directly ~o the main feed source or in series to another auxiliary feed source with the reactants therein ultima~ely terminating in the main feed souxce before entering the polymerization zone.
During these movements of reactants from one feed source to another there is a resultant continual change in the compositional content of the contents o the tank to which polymerizable reactant is added and the contents of the tanks are agitated to obtain efficie~t mixing of the contents therein. One can also vary the process by having periods of time at the start, during or near the end of the reaction wherein there is feeding of main polymerizable feed composition from the main feed source into the polymerization reactor without any simultaneous eeding of-auxiliary polymerization feed composition into the main feed source or tank for a selected period of time. In this manner, a polymer can be produced having chain sections of the type produced by conventional block or random pol~merization ~ ~ 6 ~ ~ ~ 10,830 techniques. In addition, the flow rates between feed tanks or polymerization zone can be varied at will at any time during the polymerization reaction. One can also, with suitable known means, using variable feed valves, eed polymerizable cyclic organic monomers from a plurality of auxiliary feed sources through an in-line mixer which serves as the main feed source wherein ~h~
main polymerizable feed composition is producad. The in-line mixer then feeds the main polymerizable feed composition directly into the polymerization zone.
As previously mentioned, the present invention is directed to novel polymers, which are produced by the above procas~, which have controlled ratios of primary to secondary hydroxyl end groups not heretofore obtainable independently of overall polymer chain structure. Consequently, the polymers of this inven-tion have combinatLons of properties not heretofore obtainable. The preferred comonomers used in the production of the novel polymers are ethylene oxide and propylane oxide. Conv ntional block copolymers of ethylene o~ide and propylene oxide contain substantially all primary or all secondary hydroxyl terminal groups, depending on the order of monomer feed, but do not ` include copolymers having a mixture of primary and secondary hydroxyl ter~inal groups. These block copolymers are usually hard, waxy solids at room ~ 10,830 temperature, which limits their utility as functional fluids. While random copolymers of ethylene oxide and propylene oxide can be produced as liquids, their ratio of primary to secondary hydroxyl terminal groups cannot be independently controlled, but rather it is fixed by the overall content of ethylene oxide and propylene oxide mer units in the polymer. By comparison, ethylene oxide/propylene oxide copolymers of the present invention have been produced which are liquid at room -temperature and which have ra~ios of primary to second-ary hydroxyl terminal groups ranging from less than 3 weight per cent primary hydroxyl groups to greater than 95 weight per cent primary hydroxyl groups. Further, this range of ratios of primary to secondary hydroxyl terminal groups has been obtained without varying the total amount of ethylene oxide and propylene oxide mer ; units present in the copolymer.
In producing ethylene oxide/propylene oxide copolymers of this invention by the previously d~scribed process it is particularly important to carry out the polymerization under monomer starved conditions, due to the difference in reactivities of ethylene oxide and propylene oxide. By operating under conditions appxoaching monomer starvation it is assured tha~ the compositional content of that portion of the polymer chain being formed at any particular time is virtually ~ ~ 63 ~ ~ 10,83~

the same as the compositional content of the main feed composition at that time. Thus, it is preferred to maintain atmospheric pressure in the polymerization vessel during polymerization to ensure a low concen-tration of unreacted monomers in the liquid phase and to feed monomers at a rate such that they are consumed as rapidly as they are fed. In conducting the copoly-merizations of the Examples hereinafter presented, conditions approaching monomer starvation were estab-lished and maintained by ensuring that the visuallymonitored reflux rate of unreacted oxide monomers did not exceed one drop per every 15 drops of monomer feed-stock introduced.
~;` Other than using the previously described method of feeding monomers to the polymerization zone and operating under conditions approaching monomer starvation, the method of making the novel copolymers o this invention is not different from conventional processes using random or sequential feeds~ For example, a preferred process or making ethylen~
;; oxide/propylene oxide copolymers comprises feeding the appropriate quantities of the monomers to a kettle charge containing an active hydrogen containing initiator and some base catalyst, usually the potassium alcoholate derivative of the initiator. The initiators are known to those skilled in the art and can be 10,830 ~ 3 ~ ~

monofunctional or polyfunctional. Since these comp~unds are well illustrated in the prior art, they requirQ no further elaboration to enable one skilled in the art to comprehend which compounds are intended. Any of the known active hydrogen containing initiators can be used.
They include alcohols, polyols, primary or secondary amines, hydroxyl amines and carboxylic acid compounds.
The amount of lnitiator charge is dictated by the molecular weight desired and the quantity of monomer to be fed; for example, a charge of one mole of an initiator of moLecular weight x with 2,000 grams of the oxide monomers should give a theoretical number average molecular weight of 2,000 ~ x. As a general rule the actual molecular weight achieved is somewhat below theory because side reac~ions, traces of moisture in the feed, and/or other factors tend to depress the molecular weight. A typical catalyst charge is 0.1 -0,5% by weight (such as potassium hydroxide~ based upon the final weight of product expected. The catalyst eolution can be prepared ~r~m the alcohol initiator either by direct reaction with metallic potassium or potassium hydroxide, or by an exchange reaction with some other potassium alcoholate. If KOH is used~ the water generated in the catalys~ preparation should be removed by some means such as azeotropic distillation, for example, prior to the addition of any o~ide monomer ~ 3 ~ ~ 10,~30 feeds. In the case of initiator preparation by an alcoholate exchange reaction, the lower boiling alcohol released from the added alcoholate by exchange should be removed, by distilla~ion for example, prior to the addition of oxide monomer feeds. Other alkali metals or their derivatives such as sodium, sodium hydroxide or a sodium alcoholate can be employed as polymeriza-tion catalysts also, but the potassium species are ; preferred.
The usual polymerization temperature for ethylene oxide/propylene oxide copolymerizations of this type is about 100 125C. with the preferred range being about 100-110C. In general, the temperature used should be the minimum temperature consistent with an acceptable reaction rate because higher temperatures pr~mote side reactions or isomerizations which gener-ate unsaturated species. The polymerization should be -~ conducted in the presenceo nitro~en or some other inert gas to repress oxidation reactions leadi~g to poor color. Atmospheric or superatmospheric pressures may be employed, but or purposes of the present inven-tion pressures nearer atmospheric are preferred in order to prevent an appreciable build-up of unreacted oxide monomers in the liquid phase. Upon completion of the oxide monomer addition, standard procedure is used-to cook out the ~harge for a short period of time 3 ~ ~
10,830 prior to neutralization, filtration and stripping~ The neutralization can be conducted with various mineral or organic acids, or alternatively with certain diato-maceous earths, such as magnesium silicate. Other procedures such as ion-exchanging are also acceptable.
Following neutralization, which is preerably carried out at 100-110C., the charge is filtered to remove salts of neutralization and held for a short period of time under reduced pressure so as to free it of any residual monomers or other volatiles.
It must be emphasized that this invention is not limited to any particular techniques of operation or workup. Each manufacturer has certain procedures and/or techniques which he prPfers and whic~ may be unique to his situation. The process described herein-above is for purposes of illustration; the utility of the process of this invention is not limited in scope - to any specific set of conditions or procedures.
Suitable~apparatus for carrying out the present invention is shown in the figure. Other apparatus can be used. The apparatus shown in the figure was used in carrying out the examples presented hereinafter.
Referring to th~ figure, the apparatus ill-ustrated includes a polymerization vessel or reactor 1 equipped with a stirrer 2 driven by a motor 3 and a ~ 6 ~ ~ ~ 10,830 thermocouple 4 for monitoring the temperature of poly-merization. The poLymerization vessel 1 is closed and is fitted with a vent 5 connected to a dry ice condenser 6 which i9 connected to cold traps (not shown). The polymerization vessel 1 is also fitted with an inlet 7 connected to a main feed source 8 also called feed tank I hereinafter. Feed tank I or main feed source 8 is equipped with a stirrer 9, a motor 10 and brine cooling means 11. A valve 12 ls located in the line 13 leading fr~m the main feed source 8 to the polymerization vessel 1 for controlling the rate of flow of main polymeri2able feed composition from source 8 to vessel 1. The main feed source 8 is also provided with an inlet 14 which is connected to an auxiliary feed source 15, also called feed tank II
hereinafter, which contains brine cooling means 16 and a nitrogen inlet 17. A valve 18 is located in line 19 leading from auxiliary feed source 15 to main feed source 8 or controlling the rate o~ flow of auxlliary polymerizable feed composition from auxiliary feed source lS to main feed source 8.
The arrangement depicted in the figure is ~, one of the simpler arrangements out of the many pos~
sible multiple feed tank possibilities inherent in the 10,83~

method employed to produce the novel polymers of this invention. One feature which is preferably ~ommon to all configurations is that of a mixing capability in the main eed tank 8 which ultimately feeds directly the polymerization reactor 1.
;~ The process used to produce the novel poly~
mers herein can be regarded as a multi-stage process having an infinite number of stages. Implicit in its use in the production of polymers from monomers having divergent rates of polymerization (e.g., ethylene oxide and propylene oxide) is the fulfillment of the require-ment that the polymerization be conducted under condi-tions approaching monomer starvation9 i.e., conditions which ensure that conversion of monomer feed to polymer proceeds at a rate equal to or exceeding the rate at which the monomers are introduced into the rea tion zone 1. Thus, the composition of the copolymer formed at any given instant must then necessarlly differ ~; slightly from that formed just prior to or ~ust subse-quant to it in points of time. Therefore, the compo-sitional content of monomers in the main polymerizable feed composition during formation of the terminal - portion of the polymer chain, which determines the ratio of primary to secondary hydroxyl terminal groups, can be varied by the skilled worker so as to be different from the compositional content during the formation of `' ..
, ~ 10,~30 any previously formed segment of the polymer chain.
The following examples are intended to be - illustrative only and are not intended to limit the invention in any way. Unless otherwise stated, all parts and percentages are on a weight basis and all temperatures are on the Centigrade scale.
- The evaluation tests performed in providing data in the foLlowing examples to charac~erize the produc~s of this invention analytically and ~unctionally are provided below.
A. Analytical Characterization -1. Primary: Secondary H~drox~l Terminal GroupContent - Primary hydroxyl content was determined by a pseudo first order diferential reaction kinetics approach. The copolymer is allowed to react with phenyl isocyanate and the disappearance of the NC0 band at 4.42 microns in the infraxed spectral region is observed as a function of time. The primary hydroxyl content of the polyol is obtained by determination of the e~fective fractional life time in the ure~hanation reaction and by useage of a predetermined calibration curv Secondary hydroxyl content is determined by difference.
The method requires prior knowledge of the total hydroxyl content of the sample and calls for low water contents (~ 0~87%) and low alka-li~ities (~ 0O003 meq/g) in the sample. These conditions are met by ion-exchanging the sample followed by efficient stripping.
~- 2. Molecular We~ght - Number average molecuLar weights were obtained by a wet chemicaL technique wherein ~he hydroxyl content is determined through reaction with phthalic anhydride in pyridine medium followed by titration of the excess anhydride with a skandard solution o~ sodium hydroxide.

~3 ~ 5 L0~830 3. Gross Composition - Gross compositions were deter~ined by nuclear magnetic resonance spec-troscopy in deuterochloroform solvent. The area of the propylene oxide methyl protons is substracted from the total area of all methylene and methine protons in the region of 3,2-3.0 ppm. The difference represents the contribution due to ethylene oxide.
4. ~onomer_Sequence Distribution - Where determined, this data was obtained by nuclear magnetic resonance spectroscopy in carbon disulflde solvent using tris(dipivaloyl-methanato) europium as a shift reagent.
Sequence lengths are calculated from a know-ledge of triad distribution and gross compo-sition.
B. Bulk Fluid Pr~eerties 1. Viscosity - Bulk viscosities were determined by both Brookfield Syncho-Lectric viscometer measurements and by the kinematic approach using Ubbelhode viscometers in constant temperature baths at the indicated temperatures.

2. Specific Gravit~ - Specific gravities of the bulk fluids were obtained by pyknometer measure-mants at the indicated temperatures.
C. Solution Prop~rties -eous Soiution Viscosity - Aqueous solution visc ~ ures and concen-trations were determined kinematically using Ubbelhode viscometers~at the indicated temperatures.
2- ~S~[~-n5_~[y~L85~D~ Foaming and foam stability data were obtained by agitating a 0.2 weight per cent aqueous solution of the fluid for 30 seconds in an electric blender, re~ording the times at which the liquid level generated by drainage of the foam reached various ~olume markings on the calibrated blender.

3. Wettin~har cteristics ~ Wetting character-istics of these fluids were determined by the Graves Method (see Am~rican Dyestuff Reporter ; 20, 201 (1931). In this method th~ time required for a standard cotton skein attached to a ~-fi~ o, 830 standard lead weight by a standard copper hook~o sink in a 500 ml. graduate containing a 0.1% aqueous solution of the fluid is measured;
the value reported is the average of two determinations.

4. Surface Tension - Surface tension values for 0.1 and 0.5 weight per cent aqueous solutions of these ~luids were determined using a De Nouy Ring Tensiometer and were corrected using the ring calibration value (0.896) supplied by ~he instrument manuacturer.

5. Cloud Point - Values were obtained by heating 40 ml. of a 1% aqueous solution o~ the fiuid in a large test tube suspended in a heating bath.
The solution was agitated manually with a thermometer and the cloud point was taken as the temperature at which the thermometer bulb was no longer visible due to clouding o the contained solution.
Exam~les 1 and 2 These examples illustrate the control over the ratio o~ primary to secondary hydroxyl terminal ` groups which can be achieved in preparing n-butanol initiated ethylene oxide/propylene oxide copolymers o this invention which are prepared to have an average molecular weight of about 3,000 and to contain 50/50 weigh~ per cent ethylene oxide and propylene oxide.
Cl, C2, and C3 are presented as controls to illustrate`
the comparative properties o~ conventional random copolymers and block copolymers having similar molec-ular weights and total ethylene oxide/propylene oxide contents.
An initiator/catalyst solution was prepared ;,~ .
~ by reacting 30 grams o~ potassium hydroxide pellets , ~ 10,830 with 185 grams of redistilled n-butanol in the presence of 150 grams of diisopropyl ether as an azeo-troping agent to remove the water of reaction. The reaction was run at re~lux and 9.4 grams o water were removed in a Dean-Stark trap. The diisopropyl ether -was then partially stripped off at atmospheric pressure to a temperature of about 90C. and the stripping was finished on a rotary evaporator operating at 50C. at 10 mm. Hg pressure. The viscous residue analyzed for an alkalinity content of 2.514 meq./gram, which is equivalent to a potassium butylate concentration of 28.1%.
The apparatus illustrated in the ~igure was used to prepare the copolymers. The amounts of the charges of reactants to the feed tanks and the flow rates and processing conditions are indicated in Table I. The initiator/catalyst solution was charged directly to the reaction kettle. Upon completion of the monomers charge, the reactLon mass was maintained at 110C.-115C.for 30 minutes. The product in the reaction kettle was analyzed for alkalin~ty by titration with a standard solution of O.lN HCl. The product was then neutralized by stirring for 1 hour ~- at lOO~C. with a 10% stoichiometric excess of glacial acetic acid which was followed by stirring for 4~ lo,83~

1 hour at 110C. with 15 grams of magnesium silicate.
The product was pressure filtered while hot using a commercial Sparkler filter. 250 grams of product was inally neutralized by heating for 1 hour at 55C. with a mixture of 25 grams each of an anion and a cation exchange resin in an 80/10 lsopropanol/water mixture.
The treated solution was filtered to remove the ion-exchange resins and the final product recovered by stripping to constant weight at 110C. under a pressure of 1 mm. of mercury on a rotary evaporator.
The results of these examples illustrate that the present invention provides copolymers of ethylene oxide and propylene oxide which are liquid at 30C.
and which can have either substantially all primAry hydroxyl terminal groups (e.g., greater than 90%
f primary groups~ or substantially all secondary hydroxyl terminal groups (e.g., greater than 90% secondary groups) as desirPd by the skilled worker preparing th~m. Neither the block copolymers nor the rand~m copolymer exhibited this combination of properties.
In these examples and those that follow ~he "
term "linear" feed type refers to a method of feeding the reactants in which the concentrations of ethylene oxide and propylene oxide in the main polymerizable feed source varied linearly with time. The term "skewed" feed type refers to a me~hod of feeding the ~; -35-~ 10,830 reactants in which the concentrations of ethylene oxide and propylene oxide in the main polymerizable feed source varied non linearly with time. The skilled worker in the art will be able to calculate the exact concentrations of monomers in the main polymerizable eed source at any given time on the basis of the feed tank charges and feed rates given in the ~ables.

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~63f3~ lo, 830 Examples 3-7 These examples illustrate the control over the ratio of primary to secondary hydroxyl terminal groups which can be achieved in preparing diethylene glycol initiated ethylene oxide/propylene oxide copol-ymers of this invention which are prepared to have an average molecular weight of about 5,000 to 5,000 and to contain about 75% ethylene oxide and about 25%
propylene oxide. C5, C6 and C7 are presen~ed as controls to illus~rate the comparative properties of conventional random copolymers and block copolymers having similar molecular weights and total ethylene oxide/propylene oxide contents.
An inltiator/catalyst solution was prepared by feeding a mixture o 50% aqueous potassium hydroxide solution into an agitated, refluxing mixture of 155 grams of diethylene glycol and 150 cc of diisopropyl ether. The water of reaction and the water introduced from the caustic feed were continually removed as formed by draining off the bottom layer of the diisopropyl ether-water azeotrope. Refluxing was continued until water was no longer present in the refluxing liquid.
A total of 42 grams of water was th~s removed. The diisopropyl ether was then stripped off using the proced~re described in Examples 1 and 2. The residual catalyst/initiator solution was a viscous, amber-colored -~0-~ 10,830 liquid having an alkalinity content of 2.47 meq.tgram, corresponding to a potassium ethylene glycolate content of 35.6% by weight.
The apparatus illustrated in the figure was used to prepare the copolymers~ The amounts of charges of reactants to the feed tanks and the flow rates and processing conditions are indicated in Table II. The initiator/catalyst solution was charged directly to the reaction kettl~. After completion of the monomers ~-; 10 charge, the procedure employed to prepare and recover the product was similar to that of Examples 1 and 2.
The results of these examples illustrate that a broad range of ratios of primary to secondary ~` hydroxyl terminal groups is obtainable in the copoly-:
mers of this invention without changing the overall monomer content or substantially~c-~anging the molec-ular weight.

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34~ lo 7 830 Examples_8 12 These examples illustrate the control over the ratio of primary to secondary hydroxyl terminal groups which can be achieved in preparing glycerine initiated ethylene oxide/propylene oxide copolymers of this inven-tion which are prepared to have an average molecular weight of about 3,500 to 4,Q00 and to contain about 25%
ethylene oxide and 75% propylene oxide. C8, C9 and C10 are presented as controls to illustrate the comparative properties of conventional random copolymers and block copolymers having similar molecular weights and total ethylene oxide/propylene oxide contents.
An initiator/catalyst solution was prepared by reacting 134 gr ms (1.46 moles) of glycerine with 35 grams of 50% aqueous potassium hydroxide in the presence of 150 ml. of diisopropyl ether as an azeotroping agent to remove water from the reaction system. The charge was heated at reflux until no further water could be collected in a Dean-Stark trap attached to the condenser.
Stripping of the diisopropyl ether was accompl~shed by heati~g to a kettle temperature of 110C, after which the pressure was reduced to 250 mm of Hg while stripping was continued. Traces of ether were removed by heating to 50C at 10 mm Hg pressure in a rotary e~aporator, The highly viscous residue, which was almost solid at room temperature, analyzed for an alkalinity content of -4~-~ 3~ ~ 10,830 3.17 meq./gram, which is equivalent to 41.6% by weight calculated as potassium glycerolate.
The apparatus illustrated in the figure was used to prepare the copolymers. The amounts of charges of reactants to the feed tanks and the flow rates and processing conditions are indicated in Table III. The initiator/catalyst solution was charged directly to the reaction kettle. After completion of the monomers charge, the procedure employed to prepare and recover the product was sLmilar to that of Examples 1 and 2.
The results of these examples further illus-trate that a broad range of ratios of primary to secondary hydroxyl terminal groups is obtainable in the copolymers of this invention independently of overall chain structure or monomers content.

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Claims (4)

10,830 WHAT IS CLAIMED:

1. A copolymer of (a) at least one cyclic organic monomer which undergoes ring-opening addition polymerization in the presence of an active hydrogen containing initiator to form a primary hydroxyl terminal group and (b) at least one cyclic organic monomer which undergoes ring-opening addition polymerization in the presence of an active hydrogen containing initiator to form a secondary hydroxyl terminal group, said copoly-mer having a controlled ratio of primary to secondary hydroxyl terminal groups and which is produced by continuously introducing at least one main polymerizable feed composition from a main feed source to a polymer-ization zone, said main polymerizable feed composition continually varying in compositional content of (a) and (b) therein during said continuous introduction;
simultaneously adding to said main feed source and thoroughly mixing therein at least one different auxiliary feed composition from at least one auxiliary feed source so as to continually change the composit-ional content of (a) and (b) in said main polymer-izable feed source; and polymerizing the main polymerizable feed composition introduced to the polymerization zone until desired polymerization has been achieved.

10,830

2. A copolymer as claimed in claim 1 wherein (a) is ethylene oxide and (b) is propylene oxide.

3. A copolymer as claimed in claim 2, wherein said copolymer is a liquid at 30°C. and at least 90 weight percent of its terminal hydroxyl groupsare primary hydroxyl groups.

4. A copolymer as claimed in claim 2, wherein said copolymer is a liquid at 30°C. and at least 90 weight percent of its terminal hydroxyl groups are secondary hydroxyl groups.