Acrylates as coupling agents for star-block copolymers
First Claim
1. In a process for the preparation of star-block homopolymers and copolymers of conjugated diene-monomers alone or with monovinyl aromatic monomers by the solution polymerization of the monomers with a monolithium initiator and then coupling the resultant lithiated homopolymer or copolymer with a coupling agent, the improvement comprising using as the coupling agent, in a ratio of coupling agent to lithium of from 2 to 10, a multiester of formula ##STR1## where X is the radical of a polyhydroxy compound having from 2 to 6 hydroxy groups, and n is an integer equal to the number of hydroxy groups in the polyhydroxy compound, whereby a star-block polymer having from 3 to 20 arms per molecule is formed.
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Abstract
A new class of multi-ester coupling agents has been disclosed which have the general formula, (CH2 ═CH-CO2)n X, where X is a radical from a polyhydroxy compound having 2 to 6 hydroxyl groups, and n is an integer equal to the number of hydroxy groups in the polyhydroxy compound. These coupling agents undergo anionic polymerization through the acrylate unsaturation rather than anionic attack at the ester linkage.
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Citations
8 Claims
- 1. In a process for the preparation of star-block homopolymers and copolymers of conjugated diene-monomers alone or with monovinyl aromatic monomers by the solution polymerization of the monomers with a monolithium initiator and then coupling the resultant lithiated homopolymer or copolymer with a coupling agent, the improvement comprising using as the coupling agent, in a ratio of coupling agent to lithium of from 2 to 10, a multiester of formula ##STR1## where X is the radical of a polyhydroxy compound having from 2 to 6 hydroxy groups, and n is an integer equal to the number of hydroxy groups in the polyhydroxy compound, whereby a star-block polymer having from 3 to 20 arms per molecule is formed.
Specification