Triblock copolymers of polystyrene-b-polyisoprene-b-polystyrene are produced with controlled branching in the polystyrene component. The polymers are prepared by the sequential addition of monomers and coupling agents in a living anionic polymerization. Polystyrene is first synthesized with a living chain end and then coupled with 4-(chlorodimethylsilyl)styrene to form a polystyrene star with a single living chain end at the core. Isoprene is then polymerized from the polystyrene star to yield a (star-polystyrene)-b-polyisoprene diblock. The living diblock is subsequently coupled in order to make the resulting triblock thermoplastic elastomers. The progression of the synthesis was followed by gel permeation chromatography to characterize the length of the polystyrene chain, the number of arms in the polystyrene star, and the diblock and triblock molecular weights. Copolymers were made with varying polystyrene to polyisoprene composition while also varying the length of the polystyrene chains and the number of arms in the star. Samples were made in order to study the effect of the branching on the resulting phase morphology. The morphology was investigated for as cast and annealed samples by atomic force microscopy and small angle xray scattering.

Thermoplastic elastomers with complex architecture by sequential addition

251st National Meeting (2016)

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