SYNTHESIS OF MODEL MULTIGRAFT COPOLYMERS OF BUTADIENE WITH RANDOMLY PLACED SINGLE AND DOUBLE POLYSTYRENE BRANCHES

Model multigraft copolymers of butadiene (Bd) and styrene (St) with ra ndomly placed trifunctional, poly(Bd-g-St), and tetrafunctional branch points, poly(Bd-g-St(2)), were synthesized by hydrosilylation of poly butadiene (similar to 92 wt % 1,4) with HSiMe2Cl and HSiMeCl2, respect ively, followed by reaction of the resultant silicon-chloride groups a long the backbone with polystyryllithium (PSLi). The extent of hydrosi lylation was controlled by appropriate adjustment of the [silane]/[C=C ] ratio. Characterization carried out by size exclusion chromatography (UV and RI detector), low-angle laser light scattering, differential refractrometry, and NMR spectroscopy indicated that the synthesized br anched molecules have a high degree of molecular and compositional hom ogeneity.