| Anionic polymerization methodology based upon a classical high-vacuum technique has been exploited toward the pursuit of a variety of well-defined graft copolymers. Poly(isoprene-graft-styrene) A2B2 stars, poly(isoprene-graft-styrene) regular multigrafts, and poly(butyl rubber-graft-styrene) are the three specifically targeted materials.; The A2B2 stars have one branch point, from which two polystyrene (PS) side chains are attached to a polyisoprene (PI) chain at its midpoint. The regular multigrafts bear PS side chains regularly spaced along a PI main chain, distributed either singly or clustered in groups of two or four side chains per branch point. Both of these materials are derived completely through an anionic polymerization scheme. Chlorosilane linking methods are employed and a modular synthetic strategy is taken. The regular multigraft syntheses make use of the difunctional organolithium initiator, (1,3-phenylene)-bis(3-methyl-1-phenylpentylidene) dilithium.; The butyl rubber graft materials are derived from a commercial butyl rubber product. Anionically active PS chains are covalently attached to this starting material by using a “grafting onto” approach.; The scope is synthetic in nature, with emphasis given to both synthetic technique and rigorous characterization methods of the polymerization products. |
