EP0554439A1 - Reacted composites, organic-inorganic composites, and methods for producing composites - Google Patents

Abstract

Reaction composites having primary and secondary subunits having the general formulas (I) and (II), and another composite having the general structure T-P-Si (OR) 3 and methods of producing these composites. In these formulas, T is an initiator fragment, P represents poly (diene) or poly (vinylaromatic), E is a benzyl having up to approximately 12 carbon atoms, a is 0 or 1, n is an integer between 0 and 4, POLYCOND is a partially condensed metallic polycondensate having metal atoms chosen from the group comprising silicon, zirconium, titanium, aluminum, lead, boron and tin, Z1 is an ether bond to a other subunit, Z2 is an ether bond to the polycondensate, R1 is chosen from -H and alkyls having from 1 to 8 carbon atoms, M is a metal chosen from silicon, zirconium, titanium, aluminum , lead, boron and tin or represents carbon, R2 represents alkyl or aralkyl having a molecular weight of less than 1,000,000, each m1, m2 and m3 is chosen from whole numbers from 0 to 3, m1 + m2 is an integer between 1 and 3, m1 + m2 + m3 = 3, m4 + m6 is an integer between 1 and the valence of M - 1, and m4 + m5 + m6 + m7 is equal to the valence of M.

Description

REACTED COMPOSITES, ORGANIC-INORGANIC COMPOSITES, AND

METHODS FOR PRODUCING COMPOSITES

BACKGROUND OF THE INVENTION The present invention pertains to organic- inorganic composites and to methods for producing composites. This invention more particularly pertains to (1) reacted composites formed by the reaction of reactive sites of particular organic-inorganic composites or star polymers, and a method for preparing^' those reacted composites; and (2) particular organic- inorganic composites (hereinafter referred to as "TPSi(OR)3 composites") which are non-network in nature and have an inorganic core to which organic arms are attached by Si-O-metal bonds and have reactive sites and a method for preparing those composites.

This invention relates to the following patent and applications. U.S. Patent No. 4,933,391 to

Timothy E. Long and Sam R. Turner, which is incorporated herein by reference, teaches the use of end-capped polymers. U.S. Patent No. 4,933,391 discloses polymers which have the general formula T-P- E_a- (CH2)_n-Si (OR) 3, in which T is selected from an initiator fragment, each R is independently selected from hydrogen and straight chain alkyl radicals having up to about 8 carbon atoms, E is a benzyl group or substituted benzyl group having up to about 12 carbon atoms, a is a whole number having a value of 0 or 1, n is a whole number having a value of 0 to 4, and P is a poly(vinylaromatic) or poly(diene) chain. U.S. Patent No. 5,096,942, issued March 17, 1992 to Timothy E. Long and Larry . Kelts, which is incorporated herein by reference, teaches particular organic-inorganic composites (hereinafter referred to as "TPESi(OR)3 composites") using those polymers. In U.S. Patent No.. 5,096,942, the organic-inorganic composites are disclosed as having sites reactive with small molecules and linear polymers. U.S. patent application No.

555,505 for Timothy E. Long and Sam R. Turner

(hereinafter referred to as "star polymer application") which is incorporated herein by reference, teaches polymers (hereinafter referred to as "star polymers") produced using the end-capped polymers of U.S. Patent No. 4,933,391. (TPSι(OR)₃ composites, TPESi (OR) 3 composites, star polymers and other similar organic- inorganic composites are also referred to collectively herein as "TP-organo-silanes" . ) Timothy E. Long and Larry W. Kelts are co-inventors herein. This invention and the inventions disclosed m the above-identifled patent and application are commonly assigned. The following art also relates to the application.

Antonen, U.S. 3,655,598 discloses use of trialkoxysilyl difunctional polybutadiene oligomers which are co-condenseα with Si-OH functional resins to form a network which is insoluble.

Taylor, U.S. 3,817,911 makes composites by a simultaneous syntnesis of an organic polymer and a metal oxide precursor . The system is a physical blend.

H. Schmidt, Journal of Non-crystalline Solids, 73 (1985) 681-691, furthers the concept of use of the sol-gel process to prepare compositions having inorganic and organic components. The organic part of the composite is contributed by the organic group m a trialkoxysilane, RSι(0R')3- Schmidt does not employ a telechelic, trialkoxysilyl functionalized polymer, nor use such a polymeric chain as a solubilizing agent for the composite.

Huang et al. and Glaser et al. , Polymer

Bulletin 14, 557-564 (1985) and Polymer Bulletin 19, 51-57 (1988) prepare insoluble network structures using low molecular weight monomers such as tetraalkoxysilane and titanium isopropoxide in combination with oligomeric and polymeric materials.

Mark, Che Tech April 1989, pp. 230-233, discloses a process for making a network which comprises reacting surface hydroxyls on silica filler particles with difunctionalized triethoxysilyl terminated poly(dimethylsiloxane) . The networks are insoluble.

Laible et al. , Advances in Colloid and Interface Science, 13 (1980), pps. 65-99, is similar to Mark. It teaches attaching a trialkoxysilyl monofunctionalized polymer to a silica particle.

It is therefore highly desirable to provide improved organic-inorganic composites, improved reacted composites and improved methods for producing composites. SUMMARY OF THE INVENTION

In the broader aspects of the invention, there is provided a reacted composite having primary and secondary subunits having the respective general formulas

(0-POLYCOND)_m, ^ -"m⁶ T—P—E_a-(CH₂)_n-Si-(Z¹)_m2 (R²)_m7—M (Z¹)_m4

⁽°R^{1 )} _m ^{3 (}°R¹)_m5 and , and another composite having the general structure T-P- Si(OR)3 and methods for producing those composites. In these formulas, T is an initiator fragment, P is poly(diene) or poly(vinylaromatic) , E is benzyl having up to about 12 carbons, a is 0 or 1, n is an integer from 0 to 4, POLYCOND is a partially condensed metal polycondensate having metal atoms selected from silicon, zirconium, titanium, aluminum, lead, boron, and tin, zl is an ether link to another subunit, z2 is an ether link to the polycondensate, R¹ is selected fro -H and alkyls having from 1 to 4 carbons, M is a metal selected from silicon, zirconium, titanium, aluminum, lead, boron and tin or is carbon, R2 is alkyl or arylalkyl having a molecular weight less than 1,000,000, each ml, m2, and r3 is selected from integers from 0 to 3 , ml + r_2 is an integer from 1 to 3, m + 2 + m3 = 3, ι_4 + m6 is an integer from 1 to the valence of M - 1, and m4 + m5 + δ + m⁷ = the valence of M. The term "ether link" used herein refers- to -O- linkages to carbons or to metal atoms. It is an advantageous effect of some embodiments of the invention to provide improved organic-inorganic composites, improved reacted composites and improved methods for producing composites which can provide varied τl, τ2, and T--^* reactivities.

DESCRIPTION OF A SPECIFIC EMBODIMENT

The reacted composite of the invention is a macromolecule in which two different sets of "arms" are joined to a metal condensate "core". One of the sets of arms is a polymer. The other set can be another polymer or a small molecule. Surprisingly, both sets of arms are present in large numbers and are not present on a random basis or on the basis of a competition between components in a single reaction.

The reacted composite of the invention incorporates primary and secondary subunits. The total number of subunits in a macromolecule of the reacted composite of the invention is from 3 to 50. The primary subunits have the general formula

(0-POLYCOND)_m1 T—P—E_a-(CH₂)_n-Si-(Z^,)_2

(OR¹)_m3 The secondary subunits have the general formula

T is an initiator fragment. P is a poly(vinylaromatic) or poly(diene) chain. E is a benzyl group or a substituted benzyl group having up to about 12 carbon atoms. a is 0 or 1. n is an integer having a value from 0 to 4. The moiety T-P-E_a- (CH2)n~ of the primary subunit represents a "primary arm" of the reacted composite. Each primary arm is directly bonded to a silicon atom, referred to herein collectively as primary arm silicon atoms or primary arm metal atoms.

POLYCOND is a partially condensed metal polycondensate having metal atoms selected from the group consisting of silicon, zirconium, titanium, aluminum, lead, boron, and tin. The partial condensation of the metal polycondensate means that in addition to metal condensation bonds having the general formula M-OM, in which each M is a metal, the polycondensate also includes metal non-condensation bonds having the general formula, M-OR, in which M is a metal and R is selected from hydrogen and lower alkyl groups of up to about four carbon atoms.

R! is selected from the group consisting of - H and alkyls having from 1 to 4 carbon atoms.

Zl is an ether link to a primary subunit or an ether link to a secondary subunit. z2 is an ether link to the partially condensed metal polycondensate.

M is a metal selected from the group consisting of silicon, zirconium, titanium, aluminum, lead, boron and tin or is carbon.

R is alkyl or arylalkyl and has a total molecular weight less than 1,000,000. R is not the same as the T-P-E_a- (CH2)n^_ of the primary subunit. R² represents the "secondary arm" of the reacted composite. Each R² is directly bonded to a metal atom, referred to collectively herein as secondary arm metal atoms.

Each ml, m², and n_3 is selected from integers from 0 to 3. ml + m is an integer from 1 to 3. ml + ir2 + m3 is equal to 3. m4 + 6 is an integer from 1 to the valence of M - 1. m⁴ + m5 + mδ + m⁷ is equal to the valence of M.

The "core" of the reacted composite (and the TPSi(OR)3 composites discussed below) represents the

"inorganic" portions, that is, all portions except the arms: the silicon and other metal atoms and their ether linkages and hydroxyl and alkoxy substituents. The primary subunits of the reacted composites of the invention are contributed by TP- organo-silane reactants which have primary moieties represented by the general formula )_1 T—P—E_a-(CH₂)

Z represents another primary moiety and all other designations have the same meanings as presented above in discussion of the reacted composites. Like the reacted composites of the invention, the TP-organo- silane reactants have arms and a core. The arms have the general formula T-P-E_a- (CH2)n^_ and correspond to the primary arms of the reacted composites. The core, like the core of the reacted composites, represents the remaining portions of the macromolecule: the silicon atoms and their ether linkages and hydroxyl and alkoxy substituents. The core of a TP-organo-silane reactant differs from the core of a reacted composite of the invention in that the TP-organo-silane reactant lacks secondary arm metal atoms.

In the TP-organo-silane reactants, if ml is 0, then the reactant corresponds to the "star polymers" of U.S. patent application No. 555,505. If ml is not 0, then the reactant is described herein as a "organic- inorganic composite" . In a particular embodiment of the invention, the reacted composites are prepared using novel organic-inorganic composites identified herein as "TPSi(OR)3 composites".

The TPSi(OR)3 composites of the invention are represented by the TP-organo-silane reactant formula above when a = 0 and n = 0. In the TPSi(OR)3 composites of the invention the arms have the general formula T-P-, in which T is an initiator fragment and P is a poly(vinylaromatic) or poly(diene) chain. Each polymer arm has a molecular weight of from about 1000 to about 100,000, and the average number of arms bonded to the core is from about 3 to about 50 or more. The core has a ratio of metal condensation bonds to the total number of possible metal condensation bonds within the range of from about 0.5 to about 0.9. The core has a metal content in which the ratio of moles of silicon contributed by the primary arms, that is, primary arm silicon atoms, to the total moles of metal in the core is within the range of from about 0.25 to 1 to about 4 to 1. The core is about 5 to about 30 weight percent of the TPSi(OR)3 composite. The method of the invention for producing

TPSi (OR) 3 composites has the following two steps: reacting an end-capped polymer with acidic water to prepare a prehydrolyzed intermediate in which about 50 to about 100 percent of -OR groups are converted to -OH and reacting the intermediate with a hydrolyzable metal compound. The endcapped polymers of the first step have the general formula T-P-Si(OR)3_# in which the same designations have the same meanings as in previous structure formulas. These polymers are made by bonding an endcapping group to a polymeric chain previously formed by an anionic living polymerization. The living polymerization is conducted using an olefinic unsaturated monomer and a univalent anionic initiator. Preferably an alkyllithium, alkylsodium, or alkylpotassium initiator is used.

Many unsaturated monomers containing carbon- to-carbon double bonds can be polymerized using anionic initiators to yield living polymers. These include conjugated and non-conjugated dienes and vinyl- substituted aromatic compounds. Some illustrative, but non-limiting examples of useful dienes include the conjugated dienes having up to about 18 carbons, such as 1, 3-butadiene, isoprene, 1, 3-pentadiene, 2-phenyl- 1, 3-butadiene, 1, 3-octadecene, and the like. Illustrative, but non-limiting examples of vinyl substituted aryl monomers include styrene, alpha- methyl-styrene, 4-methylstyrene, 4-tert-butylstyrene, 4-decyclstyrene, alpha-methylstyrene, 2- vinylnaphthalene, 2-vinylpyridine, and other vinyl substituted aromatics having up to about 18 carbon atoms. It will be understood by a skilled practitioner that the living polymers used as intermediates in this invention can be homopolymers, copolymers, or block copolymers. The living polymerization is conveniently carried out at a temperature of from about -85°C to about 120°C. The polymerization is also conveniently carried out in a liquid ether or an aliphatic hydrocarbon which does not react with the catalyst. Tetrahydrofuran, cyclohexane, petroleum ether, and the like can be used. When a reaction medium, such as tetrahydrofuran has a tendency to react with material (s) used in the process, such an undesirable side reaction can be minimized in some instances by conducting the process at a low temperature. Hence, one may use a reaction temperature as low as about -78°C or lower when tetrahydrofuran is employed as the reaction medium.

Further details concerning the preparation of living polymers of the type used in this invention are available in the art, e.g., U. S. Patents 4,933,391; 3,956,419; 4,371,670; 4,379,891; 4,408,017; and 4,618,650. The descriptions of living polymers and methods for their formation within those patents are incorporated by reference herein as if fully set forth. Turning now to the endcapping process, it can be applied to anionic living polymers having any molecular weight. Hence, the molecular weight is not a critical variable in the end-capping process. For convenience, it is preferred that the metal terminated polymer have a polymeric chain with a molecular weight in the range of from about 500 to about 1,000,000, more preferably from about 1,000 to about 100,000 and that the metal used be a univalent metal such as lithium, sodium, or potassium. Several criteria must be met for the selection of a suitable functionalization (endcapping) reagent. First, an electrophilic site for direct deactivation of the polymeric carbanion must be present in the molecule. Also, the reaction should be quantitative or nearly quantitative, in order to maximize the efficiency of subsequent formation of condensed products. In addition, the efficiency of the functionalization reaction should be characterizable by a variety of complimentary techniques, e.g. spectroscopic and chemical.

For this invention endcapping agents are selected from those having the formula: Ra-Si(ORb)3 .

Ra is a reactive center for nucleophilic attack by the univalent metal carbanion. R can be a halogen radical selected from fluoride, chloride, bromide, and iodide. Ra can also be a halo (lower alkyl)- moiety. Rb is an alkyl radical of up to 8 carbon atoms.

Examples of endcapping agents useful in this invention are halotrialkoxysilanes including fluoro, chloro, and bromo substituted tri(methoxy, ethoxy, butoxy) silanes. The endcapping reaction can be carried out in the reaction medium in which the metal terminated polymer is formed. The reaction temperature is not critical. It has been conducted at -78°C in tetrahydrofuran and at 60°C in cyclohexane.

Temperatures above and below those temperatures, e.g., from about -85°C to about 100°C, can be employed if desired. The reaction can be conducted for a reaction time within the range of from about 0.25 to about 2.0 hours. Shorter and longer times can be used if desired. The endcapping reaction is preferably conducted using an excess (10-100 mole percent or more) of the endcapping agent. However, it is not necessary that an excess be used; an exact stoichiometry can be employed, if desired. The process is preferentially conducted at ambient or slightly elevated pressures e.g. 1 atmosphere to about 1.1 atmosphere. Such pressures are not critical, and higher pressures or vacuum can be used if desired. The end-capped polymers prepared by reacting the metal terminated polymers and above-described end¬ capping agents are soluble in a material such as tetrahydrofuran, dimethylformamide, dimethylacetamide, acrylonitrile, N-methylpyrollidone, sulfolane, dimethylsulfoxide, and the like.

The end-capped polymers, produced as described above, are bonded to a metal polycondensate that is formed in situ from a hydrolyzable reactant MX_n> M is selected from Si, Zr, Ti, Al, Pb, B, or Sn;

X is a hydrolyzable group selected from halogen and alkoxy groups of one to about eight carbon atoms; and n is the metal valence. X and the R groups of the living polymers can be the same or can differ. Generally speaking, the alkoxy groups on the end-capped polymers react in a sol-gel hydrolysis/condensation reaction at a slower rate than the hydrolyzable groups in MX_n. In order to make the rate of reaction more balanced, the end-capped polymer is subjected to a prehydrolysis, which forms Si-OH groups available for condensation.

The prehydrolyzed intermediate produced is then reacted with the hydrolyzable reactant, one or more materials having the formula MX_n.

The conditions utilized to conduct the prehydrolysis favor hydrolysis over condensation. The differences between hydrolysis and condensation are well known to a skilled practitioner. For example the equation:

R'Si(OR)₃+3H₂0 R'Si(OH)₃+3ROH illustrates complete hydrolysis of a trialkoxysilane such as a trimethoxysilane or triethyoxysilane. As shown, for each mole equivalent of trialkoxysilane employed, three moles of water are required for complete hydrolysis (ignoring any water produced by condensation) . For the purposes of this application, certain terminology is employed to describe features of this invention. Thus, Si-OR and Si-OH bonds illustrated by equation (1) are termed "non- condensation bonds." In such bonds, silicon is not linked through an oxygen bridge to another metal atom. On the other hand, bonds in which metal atoms are linked through an oxygen bridge to form M-O-M groups, wherein each metal atom M is alike or different and is selected from the metals represented by M as stated above, are called "metal condensation bonds." An illustrative M-O-M group is an Si-O-Si group. An M-O-M group contains two metal condensation bonds.

The products and intermediates in the process of this invention can be characterized by the following ratio: actual number of metal condensation bonds p = total number of possible condensation bonds

The reaction can be followed using 29si NMR analysis to determine the actual number of metal condensation bonds formed. The total possible condensation bonds that can be formed can be calculated from the moles of hydrolyzable metal compound times the number of replaceable groups in the molecule that can condense.

For the polymeric silicon-containing reactant T-P-Si(OR)3, the total possible metal condensation bonds is (number of moles) x 3.

The reaction conditions employed to conduct the prehydrolysis step in the process of this invention are not critical. One generally uses reaction conditions that favor hydrolysis over condensation and conducts the reaction under the selected set of reaction conditions to achieve the desired rate of hydrolysis. In general, one adds enough water to the reaction and conducts the process so that on a theoretical basis, all -OR groups could hydrolyze.

Thus for prehydrolysis of all three alkoxy groups on the T-P-Si(OR)3 endcapping reactant, one generally uses at least three moles of water per each mole of the polymeric reactant. It is to be understood that less than three moles of water can be employed especially if it is desired to hydrolyze less than all of the alkoxy groups present in the polymeric reactant. It is convenient to use about 4 moles, of water for each mole of endcapping reactant, however, there is no real upper limit on the amount of water to be employed. It is preferred that the amount of water not exceed about 20 moles per mole of T-P-Si(OR)3 reactant. Thus, per each mole portion of the polymeric reactant, it is generally preferred to use from about 2.0 to about 6.0 moles of water in the prehydrolysis and thus provide a prehydrolyzed intermediate having, theoretically, about 50 to about 100 percent of the OR groups converted to OH. It is to be recognized, however, that the amount of water employed can be somewhat outside this range. Although the prehydrolysis is preferably conducted in an acidic medium for the preparation of other TP-organo-silanes, such as TPESi(OR)3 composites, the prehydrolysis for the preparation of TPSi(OR)3 composites is slow in an acidic medium. This is surprising since, as is known in the sol-gel art, hydrolysis is fast under acidic conditions (low pH) . The acidic medium also provides acid as catalyst for the condensation reaction, however, in the case of TPESi (OR) 3 composites the acid undesirably drives the reaction toward condensation. If there is an appreciable amount of condensation, then an appreciable amount of starting polymeric reactant will be transformed into a material with limited available sites for reaction with the MX_n reactant, and the yield of desired product will be reduced. For prehydrolysis, a reaction temperature is selected which gives a suitable reaction rate, and which does not cause an undesirable amount of condensation (of hydrolyzed functionalized polymer) . In general, one employs a reaction temperature within the range of from about -35°C to about 75°C.

Temperatures somewhat outside this range can also be employed. Preferably, one employs a reaction temperature within the range of from about -20°C to about 60°C.

Generally speaking, faster rates of hydrolysis are obtained with higher reaction temperatures. Also, condensation is usually faster with higher reaction temperatures. As indicated above, for the purpose of this invention condensation of the prehydrolyzed intermediate can be objectionable, since it diminishes the ability of this intermediate to react with the MX_n reactant employed in the second step of the process of this invention. Therefore, when selecting a reaction temperature, or a regime of reaction temperatures, one keeps in mind not only the desire to achieve a suitable hydrolysis reaction rate, but also the desire to refrain from producing an unacceptable amount, for example, greater than 50 percent, of undesired condensation product. Thus, one chooses a reaction temperature (or temperatures) which "balances" (a) the rate of the desired prehydrolysis, with (b) the rate of the undesired condensation of the prehydrolyzed intermediate, so that hydrolysis is heavily favored, and any condensation is maintained within an acceptable amount. The reaction time is not a truly independent variable, but it is dependent at least to some extent on the other reaction conditions employed; for example, the reaction temperature, the inherent reactivity of the reactant, the efficiency of the catalyst employed, etc. In general, one employs a reaction time that strikes a favorable balance between the hydrolysis that is desired, and (undesired) condensation of the prehydrolyzed intermediate. Such a reaction time can be selected with a limited amount of preliminary experimentation, especially if the reaction results are followed using 29si NMR as an experimental tool. As shown by the examples, a suitable prehydrolysis reaction time can be about one hour. Greater or lesser reaction times can be employed. Thus, reaction times for the prehydrolysis are generally in the range from about five minutes to about five hours. Reaction times somewhat outside this range can be used.

The reaction pressure is not critical. In general, the prehydrolysis is conducted at ambient pressure; however, greater and lesser pressures can be used if desired. For example, one may wish to run the prehydrolysis at a reduced pressure to facilitate hydrolysis, e.g. when the hydrolysis by-product is a volatile species such as isobutylene, methanol or n- butanol. Thus for example, one may use a reaction pressure of from about 0.1 to about 1.0 atmospheres.

Pressures above and below this range can also be used.

After the prehydrolysis, the prehydrolyzed intermediate is condensed with the MX_n reactant. The mole ratio of MX_n to intermediate is from about 0.25 to 1 to about 4 to 1. This step can involve a partial hydrolysis of the MX_n reactant prior to its condensation; however, it is to be understood that the condensation can at least to some extent occur via an alcohol producing condensation or similar reaction such as illustrated using a silicon tetraalkoxide by the equation:

T-P-Si(OR)₂OH +RO-Si(OR)₃ T-P-Si(OR)₂-O-Si{OR)₃+ R-OH.

In general, water producing condensations are faster than alcohol producing condensations, especially in silicon systems. With other metal alkoxides, alcohol producing condensation reactions become more important. Titanium and zirconium alkoxides hydrolyze and condense much faster than silicon alkoxides. When mixed with silicon hydroxides, they can catalyze silicon condensation, or condense rapidly with silicon alkoxides themselves.

It is to be understood that the water necessary for the composite forming step can come from three sources: (1) water present in the acid/water mixture at the end of the prehydrolysis step, (2) water that evolves from the water producing condensation reaction, and (3) water added at the beginning or during the composite forming step. It is often favorable to limit the amount of water present when the MX_n reactant or reactants are added. It may be convenient to conduct the composite forming step in the presence of the acid/water mixture which remains after the prehydrolysis step and which contains the prehydrolyzed intermediate. The MX_n compound can be added all at once or in increments.

The composite forming reaction is generally conducted at a temperature in the range of from about -35°C to about 130°C and preferably is conducted at a temperature of from about -10°C to about 75°C. Reaction at room temperature or thereabouts is highly preferred in many instances.

The time employed for the composite forming step is not a truly independent variable, but is dependent at least in part on the inherent reactivity of the reacting materials, the quantity employed, the catalyst used, and the reaction temperature (s) selected. Generally speaking, this time is from 30 minutes to 250 hours. The reaction pressure can be selected from those pressures discussed above when the prehydrolysis step was described.

The TPSi(OR)3 composites of the invention have M-OH groups contributed by both the MX_n reactant and the endcapped polymer. A surprisingly large percentage of these M-OH groups, also referred to herein as "reactive sites", can be reacted to provide additional M-OM bridges. This reaction is utilized in the method of the invention for the preparation of reacted composite to produce one of the embodiments of the reacted composites of the invention.

Alternative embodiments of the reacted composites of the invention can be produced from organic-inorganic composites disclosed in U.S. Patent No. 5,096,942. Disclosed therein are organic-inorganic composites prepared by the reaction of endcapped polymers having the general structure TPESi(OR)3 and MX_n reactants, in which T and P and other designations are the same as elsewhere herein. Other alternative embodiments of the reacted composites of the invention can be prepared from the star polymers disclosed in U.S. patent application No. 555,505. In the method of the invention for preparing reacted composites, TP-organo-silane, such as a TPSi (OR) 3 composite or star polymer, is reacted with a

"secondary condensation reactant", that is, a small molecule or linear polymer bearing a group which is capable of reacting with the H- of a silanol or other metal hydroxy and forming an M-O-M bridge. Exemplary silanol group reactions are tabulated in Her, Ralph K. , "The Chemistry of Silica", John Wiley & Sons, New York, 1979. Suitable secondary condensation reactants are chlorosilanes, carboxylic acids, alkoxysilanes, and alcohols. Specific examples of useful secondary hydrolysis-condensation reactants are: trimethylchlorosilane, methacryloxypropyldimethyl- chlorosilane, n-decyldimethyl-chlorosilane, 3- cyanopropyldimethylchlorosilane, 2- (4- chlorosulfonylphenyl) ethyldimethylchlorosilane, 3- chloropropyldimethylchlorosiloane, n-butyldimethyl- chorosilane, 1, 6-bis (chlorodimethylsilyl)hexane, and 3- aminopropyldiisopylethoxysilane. Useful linear polymers include the above-disclosed endcapped polymers having the general structure TPSi (OR) 3 and endcapped polymers disclosed in U.S. Patent No. 4,933,391. Other suitable linear polymers are disclosed in the other references listed above for endcapped polymers. Because of this capacity to incorporate a variety of moieties, the reacted composites of the invention can have a wide variety of uses. For example, the reactive sites can carry and, in effect, disperse in a film or the like specific groups which provide a desired function, such as dye moieties for photography. Reaction of the organic-inorganic composite or star polymer and the secondary condensation reactant is performed in solution or as a melt without solvent or with a non-solvent. If solvent is used, selection of that solvent is not critical. Suitable solvents include cyclohexane, toluene, chloroform, and other similar materials. A convenient solution concentration is 15-20 percent solids. The reaction temperature is not critical, however, a temperature of 25°C or higher is desirable to increase the rate and extent of reaction. Any reaction pressure can be employed, however, atmospheric pressure is convenient.

The secondary condensation reactant can be added in an amount in stoichiometric excess of the number of reactive sites or a less amount may be used if incomplete reaction is desired. A convenient amount of secondary condensation reactant for high levels of conversion is a tenfold excess of reactant to residual reactive silanols. The reaction can be allowed to proceed until the level of conversion has reached a constant value by ²9si NMR analysis. Convenient times are generally 0.2 to 48 hours.

The reacted composite produced can be isolated from solution by solvent evaporation or precipitation into nonsolvent. The latter procedure provides the added benefit of removing any unreacted silane. Reacted composites can be differentiated from their precursors on the basis of the presence of secondary subunits and also on the basis of relative percentages of metal atoms bearing different numbers of -OM groups, that is metal atoms bonded by 1, 2, 3, or more oxygen bridges to other metal atoms. The following nomenclature is used herein to designate those metal atoms. The terms " l", "T²", and so on, each refer to a silicon atom contributed by endcapped polymer bearing the superscripted number of -OM groups. Thus, for example, a τl silicon is bonded to one other metal atom through an oxygen bridge. Each silicon in the moiety Si-O-Si is a T**- silicon. The terms "Q3" and the like refer to metal atoms of the inorganic core, contributed by the MXn reactant, bearing the superscripted number of oxygen-metal bridges. Star polymers and reacted composites of star polymers lack Q3 and Q⁴ metal atoms. In the following, "T" and "Q" metal atoms are described as percentages of total metal atoms. Percent condensation is equal to the number of condensed metal atoms, that is, "T" and "Q" metal atoms, divided by the total number of metal atoms, both condensed and uncondensed.

In the reacted composites of the invention, the percentage of T² metal atoms decreased and the percentage of τ metal atoms increased in comparison to star polymer precursors. For organic-inorganic composite precursors, the percentages of both and Q metal atoms decreased and the percentages of 3 and Q⁴ metal atoms increased. Overall, the conversion of star polymer or organic-inorganic composite to reacted composite resulted in an increase in the condensation of metal atoms of about 50 to about 90 percent. This extent of incorporation of additional moieties into the star polymers and organic-inorganic composites was surprising. This is particularly true in view of the anomalous behavior of τl metal atoms. In Example 1, a star polymer was 66 percent condensed and the reacted composite was 74 percent condensed. The star polymer was 16 percent τl. In the reacted composite no τl metal atoms were observed. In Example 4, a TPSi(OR) 3 composite showed 8 percent τl groups. The reacted composite showed 7 percent τl groups. This difference in the reactions of τl metal atoms in the methods of the invention for preparing reacted composites is very surprising and cannot be fully explained, other than noting that sterically hindered sites are evidenced by limited cluster growth and thus the Examples evidence unexpected differences m the accessibility of reactive sites .

Preparation of C^H polystyrene-CHo-para-phenyl-

Sι^(QCH₃_.3 endcapped polymer

All glassware was rigorously cleaned and dried in an oven at 120°C for 24 hours. The reactor was a 250 mL, 1 neck, round-bottom flask equipped with a magnetic stirrer and a rubber septum. The septum was secured in place with copper wire in order that a positive pressure of ultra pure nitrogen could be maintained. The reactor was assembled while hot, and subsequently flamed under a nitrogen purge. After the flask had cooled, the polymerization solvent (tetrahydrofuran) was added to the reactor via a double-ended needle (cannula) . The reactor was submerged into a -78°C bath and allowed to reach thermal equilibrium. Purified styrene monomer was charged into the reactor with a syringe. The calculated amount of initiator was quickly syringed into the reactor and immediately one could see the formation of the orange polystyrl lithium anion. The polymerization was allowed to proceed for 20 minutes to ensure complete conversion. Upon completion of the polymerization, the endcapping reagent (50% molar excess compared to lithium) was added quickly via a syringe. The complete disappearance of the orange color was indicative of complete deactivation of the polymeric carbanion. After functionalization, the polymers (molecular weights greater than 3000 g/mole) were precipitated in HPLC grade methanol which contained <0.05% water (determined by titration) . The precipitation and vacuum filtration were conducted under a nitrogen blanket to minimize hydrolysis of the trialkoxysilyl end-groups. Residual solvent was removed in vacuo at 80°C for 12 to 18 hours.

Preparation of the star polymer:

C4H9-polystyrene-CH2-para-phenyl-Si(OCH3)3 endcapped polymer was dissolved in tetrahydrofuran to provide an approximately 15-18 percent (weight/weight) solution. A 4:1 molar ratio of water to silicon (based on polymer repeat unit molecular weight) was added as a 0.15 N solution of HC1. The solvent was allowed to evaporate slowly at room temperature for 4 days. The reaction product was then heated at 120°C for 48 hours.

Preparation of (T-P-E-Si(OR)3_ composite

Approximately 1.0 grams of C4H9-polystyrene- CH2-para-phenyl-Si(OCH3)3 endcapped polymer was dissolved in tetrahydrofuran (approximately 0.075 M) . The endcapped polymer was then prehydrolyzed. For the prehydrolysis, a 1.0 M HC1 solution was added to the tetrahydrofuran solution of the polymer in an amount such that the water:silicon ratio was 4:1. The resultant mixture was maintained at 30°C for 1.0-1.5 hours at atmospheric pressure. The resulting solutions were characterized by 29si NMR at the end of the hydrolysis period to ascertain that hydrolysis was complete and an acceptably low amount of condensation had taken place.

After prehydrolysis, the MX_n reactant: tetramethoxysilane (also referred to herein as "TMOS") sufficient to provide approximately 10 weight percent TMOS was added to the THF/aqueous mixture of the prehydrolyzed polymer. The reaction mixture was then maintained at 30°C and ambient pressure for approximately 36 hours. Liquid was then evaporated from the resultant mixture.

The following examples are presented for a further understanding of the invention:

EXAMPLE 1

Star polymer was prepared as disclosed above using C-jHg-polystyrene-C^-para-phenyl-Si (OCH3)3 end¬ capped polymer having a molecular weight of 2,900 determined by Size Exclusion Chromatography (SEC) in tetrahydrofuran at 30°C using a viscometry detector and universal calibration with polystyrene standards. 29si Nuclear magnetic resonance characterization was per¬ formed using a Bruker AM-500 spectrometer at 99.32 MHz. All samples were referenced to tetramethylsilane (TMS) . Chromium acetylacetonate [Cr(acac)3] was added at approximately 0.015 M to reduce the longitudinal relax¬ ation time for the 29si NMR spectra. The spectra were obtained using inverse-gated decoupling (decoupler on during acquisition and off during relaxation delay) to suppress any negative nuclear Overhauser effect. The relaxation agent and decoupling sequence facilitated quantitative measurements. The 29si NMR indicated that silicon atoms were condensed 66% percent to Si-O-Si and that the distribution was 16% T¹, 70% T², and 14% T³.

The star polymer was readily dissolved in tetrahydrofuran at 25°C to provide a 15-20 percent

(weight/volume) . An excess of trimethylchlorosilane was added. The reaction was allowed to proceed for several hours and then the reacted composite was isolated by precipitation in a nonsolvent: methanol followed by evaporation of the nonsolvent. 29si NMR analyses, conducted as above-described gave a final distribution of 0% T¹, 52% T² , and 48% T³.

EXAMPLE 2

The star polymer was prepared as described in

Example 1. The star polymer was then dissolved in tetrahydrofuran at 25°C to provide a 15-20 percent (weight/volume) solution. Endcapped polymer trimethoxy(silylphenylmethyl) terminated polystyrene, which has the general formula T-P-E-Si (OCH3) 3, and having the molecular weight of 10,100 was added to the star polymer solution. The reaction mixture was maintained at 25°C for 24 hours. The reacted composite produced was isolated by drying and precipitation. Molecular weight analysis of the reacted composite produced was conducted as described in Example 1 and indicated an increase in molecular weight equivalent to the addition of 2.4 endcapped polymer moieties to each star polymer macromolecule. EXAMPLE 3

The procedures of Example 2 were followed with the following exceptions. The endcapped polymer used was the same as in Example 2 except the molecular weight was 45,800. The reaction mixture was allowed to react for 24 hours. Molecular weight analysis of the reacted composite produced was conducted as described in Example 1 and indicated an increase in molecular weight equivalent to the addition of 1.1 endcapped polymer moieties to each star polymer macromolecule. EXAMPLE 4

The TPSi (OR) 3 composite was prepared as follows. Approximately 1.0 grams of C4H9~polystyrene- benzyl-Si (OCH2CH3) 3 endcapped polymer was dissolved in tetrahydrofuran (approximately 0.075 M) . The endcapped polymer was then prehydrolyzed. For the prehydrolysis, a 1.0 M HC1 solution was added to the tetrahydrofuran solution of the polymer in an amount such that the water: silicon ratio was 4:1. The resultant mixture was maintained at 30°C for 22.0 hours at atmospheric pressure, at which time an additional 16 equivalents of 1 M HC1 was added. Since hydrolysis and condensation were especially slow in this system, the reaction was allowed to continue at that temperature and pressure for an additional 47 hours. The resulting solutions were then characterized by 29si NMR to ascertain that hydrolysis was complete and an acceptably low amount of condensation had taken place. Two equivalents of tetraethyl orthosilicate (Si- (OCH2CH3)4) were then added. After reacting for 12 days the reaction mixture was heated above its Tg, (to 110°C) , to push the condensation reaction to an acceptable level.

The TPSi (OR) 3 composite was analyzed as follows: 29si Nuclear magnetic resonance characterization was performed as in Example 1 and indicated that silicon atoms were condensed as follows: T 63% and Q 85%. The distribution was 13% T¹, 31% T², 7% T³, 30% Q³ and 19% Q⁴. The organic-inorganic composite was readily dissolved in tetrahydrofuran at 25°C. Trimethylchorosilane was added in a ten-fold excess and the reaction mixture was reacted for about 5 hours at 25°C. Analyses, conducted as described above, gave a final distribution of 10% τ , 20% T², 20% T³, 15% Q³ and 35% Q⁴. The final values for condensation were T 73% and Q 93%. EXAMPLE 5

TPESi(OR)3 composite was prepared as described above, having a molecular weight of approximately 100,000 determined by the same procedures used in Example 1. 9si Nuclear magnetic resonance characterization was performed as in Example 1 and indicated that silicon atoms were condensed as follows: T 82% and Q 85%. The distribution was 15% T², 12% T³, 5% Q², 34% Q³ and 34% Q⁴. The organic- inorganic composite was readily dissolved in tetrahydrofuran at 25°C. Trimethylchorosilane in ten¬ fold excess was added and the reaction mixture was reacted for 48 hours at 25°C. Analyses, conducted as described above, gave a final distribution of 8% _^■•*^•■, 20% T³, 16% Q³ and 56% Q⁴. The NMR integrals indicated that the T type silicons were 91% condensed and the Q type silicons were 95% condensed.

While specific embodiments of the invention have been shown and described herein for purposes of illustration, the protection afforded by any patent which may issue upon this application is not strictly limited to a disclosed embodiment; but rather extends to all modifications and arrangements which fall fairly within the scope of the claims which are appended hereto:

Claims

WHAT IS CLAIMED IS:

1. A reacted composite having primary and secondary subunits, said primary subunits each having the general formula _m1 j—p—_Ea_₍CH₂)

and said secondary subunits each having the general formula

wherein in the above formulas, T is an initiator fragment,

P is a poly(vinylaromatic) or poly(diene) chain,

E is a benzyl group or a substituted benzyl group having up to about 12 carbon atoms, a is 0 or 1, n is an integer having a value from 0 to 4,

POLYCOND is a partially condensed metal polycondensate having metal atoms selected from the group consisting of silicon, zirconium, titanium, aluminum, lead, boron, and tin, zl is an ether link to a primary subunit or an ether link to a secondary subunit,

Z² is an ether link to said partially condensed metal polycondensate,

R! is selected from the group consisting of -H and alkyls having from 1 to 4 carbon atoms,

M is a metal selected from the group consisting of silicon, zirconium, titanium, aluminum, lead, boron and tin or is carbon, R2 is alkyl or arylalkyl having a total molecular weight less than 1,000,000 each ml, m², and m³ is selected from integers from 0 to 3, m + m² is an integer from 1 to 3, ml + m² + ³ is equal to 3, m⁴ + mδ is an integer from 1 to the valence of M - 1, m⁴ + m5 + mδ + m⁷ is equal to the valence of M, with the proviso that R² is not the same as T-P-E_a-(CH2)n~•

2. The reacted composite of claim 1 wherein said T-P-E_a- (CH2)n^_ and R2 moieties each have a molecular weight from about 1000 to about 100,000, and the average number of said subunits bonded together is from about 3 to about 50.

3. The reacted composite of claim 1 wherein n is 0,

4. The reacted composite of claim 3 wherein a is 0

5. The reacted composite of claim 1 wherein for each said primary moiety, ml is an integer from 1 to 3.

6. The reacted composite of claim 5 wherein a is 0 and n is 0.

7. The reacted composite of claim 5 wherein said T-P-E_a- (CH2)n~ and R² moieties are more than 70 weight percent of said reacted composite.

8. The reacted composite of claim 1 wherein for each said primary subunit, ml is 0.

9. The reacted composite of claim 1 wherein T is C4H9 and Rl is CH3 or CH2-CH3.

10. A process for the preparation of a reacted composite comprising reacting (i) one mole portion of a reactant having a plurality of primary subunits, each said primary subunit having the the general formula T—^p—E_a-(^CH ₂)

/ wherein T is an initiator fragment, P is a poly(vinylaromatic) or poly(diene) chain, E is a benzyl group or a substituted benzyl group having up to about 12 carbon atoms, a is 0 or 1, n is an integer having a value from 0 to 4, POLYCOND is a partially condensed metal polycondensate having metal atoms selected from the group consisting of silicon, zirconium, titanium, aluminum, lead, boron, and tin, zl is an ether link to another primary subunit, R! is selected from the group consisting of -H and alkyls having from 1 to 4 carbon atoms, ml + m.2 is an integer from 1 to 3, and ml + m² + 3 is equal to 3; with (ii) a secondary hydrolysis-condensation reactant selected from the group consisting of chlorosilanes, carboxylic acids, alkoxysilanes, and alcohols.

11. The process of claim 10 wherein said T-P- E_a-(CH2)n~ moieties each have a molecular weight from about 1000 to about 100,000.

12. The process of claim 10 wherein n is 0.

13. The process of claim 12 wherein a is 0.

14. The process of claim 10 wherein for each said primary subunit, ml is an integer from 1 to 3.

15. The process of claim 10 wherein for each said primary subunit, l is 0.

16. An organic/inorganic composite, said composite having a core, and a plurality of arms chemically bonded to said core, said core being a partially condensed metal polycondensate of silicon, zirconium, titanium, aluminum, lead, boron or tin, wherein (a) the ratio of metal condensation bonds, M-O-M, in said core to the total number of possible metal condensation bonds is within the range of from about 0.5 to about 0.9, and (b) in the metal non-condensation bonds having the formula M-OR, R is selected from hydrogen and alkyl groups having from 1 to 8 carbon atoms; said core being further characterized by having a metal content such that the ratio of moles of metal contributed by metal atoms directly bonded to said polymer arms, to the total moles of metal in said core is within the range of from about 0.25/1 to about 4/1; said core being still further characterized by being from about 5 to about 30 weight percent of said composite; said arms having the general formula

T—P—E_a-(CH₂)_n-Si-0-

wherein at least one of the Si-O- bonds is bonded directly to said core, or indirectly to said core through another silicon atom directly bonded to another arm, and any remaining Si-O- bonds are attached to R wherein R is as defined above, T is an initiator fragment, P is a poly(vinylaromatic) or poly(diene) chain, a is a whole number having a value of 0 or 1, n is a whole number having a value of 0 to 4, and E is a benzyl group or a substituted benzyl group having up to about 12 carbon atoms; said composite being further characterized by each of said arms having a molecular weight of from about 1000 to about 100,000, and the average number of arms bonded to said core being from about 3 to about 50, with the proviso that if a is 1, then n is an integer from 1 to 4.

17. The organic-inorganic composite of claim 16 wherein a equals 0 and n equals 0.

18. The organic-inorganic composite of claim

16 wherein T is an alkyl group of from 2 to about 6 carbon atoms .

19. A process for preparing an organic- inorganic composite having an inorganic core, and a plurality of organic polymer arms chemically bonded to said core, said process comprising reacting (i) one mole portion of an end¬ capped polymer having the formula: T-P-Ea- (CH2)n^_ Si (OR) 3 wherein T is selected from an initiator fragment, each R is independently selected from hydrogen and alkyl radicals having from 1 to 4 carbon atoms, P is a poly (vinylaro atic) or poly(diene) chain, a is a whole number having a value of 0 or 1, n is a whole number having a value of 0 to 4, and E is a benzyl group or a substituted benzyl group having up to about 12 carbon atoms, with the proviso that if a is 1, then n is an integer from 1 to 4; with (ii) about 4 mole portions of acidic water to prepare a prehydrolyzed intermediate; and reacting said intermediate with from 0.25 to about 4 moles per mole of said intermediate of a hydrolyzable metal compound MX_n, wherein M is selected from Si, Zr, Ti, Al, Pb, B, or Sn, and X is a hydrolyzable group selected from halogen and alkoxy groups having from 1 to 8 carbon atoms.