Star polymers from mixed initiators

Multi-branched or star-shaped polymers having mixed functional and non-functional ends produced by a process comprising the steps of:

• (a) polymerizing conjugated alkadienes, comprising the group of butadiene and isoprene, or alkenylsubstituted aromatic compounds, comprising the group of styrene and alpha-methylstyrene singly, sequentially, or as mixtures thereof, in a liquid reaction medium, at a temperature of -30.degree. C. to 150.degree. C., for a period of at least one hour, separately with (a) alkyllithium initiators, comprising the group of n-butyllithium, sec-butyllithium, and tert-butyllithium and (b) protected functional organolithium initiators, having the formula:
• Li--Q.sub.n --Z--T--(A--R.sup.1 R.sup.2 R.sup.3).sub.m
• where Q is an unsaturated hydrocarbyl group derived by incorporation of one or more conjugated diene hydrocarbons, one or more alkenylaromatic compounds, or mixtures of one or more dienes with one or more alkenylaromatic compounds into the Li--Z linkage at a carbon-lithium bond thereof;
• Z is defined as a branched or straight chain hydrocarbyl connecting group containing 3 to 25 carbon atoms;
• T is an element selected from the group of oxygen, sulfur, and nitrogen;
• (A--R.sup.1 R.sup.2 R.sup.3).sub.m is a protecting group in which A is an element selected from Group IVa of the Periodic Table of the Elements;
• R.sup.1,R.sup.2, and R.sup.3 are independently selected from hydrogen, alkyl, substituted alkyl groups containing lower alkyl, lower alkylthio, and lower dialkylamino groups, aryl or substituted aryl groups containing lower alkyl, lower alkylthio, lower dialkylamino groups, or cycloalkyl and substituted cycloalkyl groups containing 5 to 12 carbon atoms;
• m is 1 when T is oxygen or sulfur and 2 when T is nitrogen;
• and n is an integer from 0 to 5, to separately produce protected "living" polymer anions;
• (b) Mixing the separately produced "living" anions, then reacting the living polymer anions with a compound selected from the group of polyfunctional linking compounds, as exemplified by silicon tetrachloride, tin tetrachloride, phosphorus trichloride, isomeric diisopropenylbenzenes and isomeric divinylbenzenes, and mixtures of these compounds at a temperature of 20.degree. C. to 135.degree. C., for a period of at least one hour, to produce multi-arm star polymers;
• (c) Removing the protecting group to produce functionalized multichelic multi-arm or star polymers with hydroxyl, sulfhydryl or amino groups on the ends of some of the arm of the multi-arm or star polymers;
• (d) Reaction of the functional groups on the ends of the arms of the polymer with a selected difunctional or polyfunctional comonomer or comonomers selected from the group consisting of organic dicarboxylic acids, organic polycarboxylic acids, organic diisocyanates, organic polyisocyanates, organic diamides, organic polyamides, cyclic amides, organic diols, organic polyols, ethylene oxide in the presence of potassium butoxide, and methacryloyl chloride, acryloyl or styrenyldimethylchlorosilane the last three of which are subsequently copolymerized with a free radically polymerizable monomer;
• (e) Recovering the multi-arm star polymers from the reaction medium.

A multi-branched or star-shaped polymer having mixed functional and non-functional ends produced by a process comprising:

• polymerizing at least one monomer selected from the group consisting of conjugated alkadienes, alkenylaromatic compounds, and mixtures thereof, with mixtures of (a) at least one alkyllithium initiator and (b) at least one protected functional organolithium initiator of the formula
• Li--Q.sub.n --Z--T--(AR.sup.1 R.sup.2 R.sup.3)
• wherein:
• Q is an unsaturated hydrocarbyl group derived by incorporation of at least one compound selected from the group consisting of conjugated diene hydrocarbons, alkenylaromatic compounds, and mixtures thereof;
• n is an integer from 0 to 5;
• Z is a branched or straight chain hydrocarbyl connecting group containing 3-25 carbon atoms;
• T is oxygen;
• (A--R.sup.1 R.sup.2 R.sup.3) is a protecting group in which A is carbon and R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, alkyl, substituted alkyl groups containing lower alkyl, lower alkylthio, or lower dialkylamino groups, aryl, substituted aryl groups containing lower alkyl, lower alkylthio, or lower dialkylamino groups, cycloalkyl and substituted cycloalkyl groups containing 5-12 carbon atoms, to produce protected living polymer anions;
• reacting the living polymer anions with a polyfunctional linking agent to produce multi-arm star polymers;
• removing the protecting group A--R.sup.1 R.sup.2 R.sup.3 to produce functionalized multichelic multi-arm or star polymers with hydroxyl groups on the end of some of the arms of the multi-arm or star polymer;
• and
• reacting the hydroxyl groups with at least one comonomer to produce a block copolymer.

A multi-branched or star-shaped polymer having mixed functional and non-functional ends produced by a process comprising:

• polymerizing at least one monomer selected from the group consisting of conjugated alkadienes, alkenylaromatic compounds, and mixtures thereof, separately with (a) at least one alkyllithium initiator and (b) at least one protected functional organolithium initiator of the formula
• Li--Q.sub.n --Z--T--(AR.sup.1 R.sup.2 R.sup.3)
• wherein:
• Q is an unsaturated hydrocarbyl group derived by incorporation of at least one compound selected from the group consisting of conjugated diene hydrocarbons, alkenylaromatic compounds, and mixtures thereof;
• n is an integer from 0 to 5;
• Z is a branched or straight chain hydrocarbyl connecting group containing 3-25 carbon atoms;
• T is oxygen;
• (A--R.sup.1 R.sup.2 R.sup.3) is a protecting group in which A is carbon and R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, alkyl, substituted alkyl groups containing lower alkyl, lower alkylthio, or lower dialkylamino groups, aryl, substituted aryl groups containing lower alkyl, lower alkylthio, or lower dialkylamino groups, cycloalkyl and substituted cycloalkyl groups containing 5-12 carbon atoms, to produce protected living polymer anions;
• reacting the living polymer anions with a polyfunctional linking agent to produce multi-arm star polymers;
• removing the protecting group A--R.sup.1 R.sup.2 R.sup.3 to produce functionalized multichelic multi-arm or star polymers with hydroxyl groups on the end of some of the arms of the multi-arm or star polymer;
• and
• reacting the hydroxyl groups with at least one comonomer to produce a block copolymer.