MULTIARM STAR POLYISOBUTYLENES .3. NEW INSIGHT INTO THE CHEMISTRY OF STAR-FORMATION - STAR-STAR COUPLING AND CORE CONTRACTION

Details of the chemistry of linking living polyisobutylene (PIB+) pre- arms with divinylbenzene (DVB) to multi-arm PIB stars have been studie d by triple-detector size-exclusion chromatography (SEC). Computer-aid ed deconvolution of multimodal differential refractive index (RI), las er light scattering (LLS), and ultraviolet (UV) traces obtained by SEC indicates the formation of complex product mixtures. The observations were interpreted in terms of inter- and intramolecular reactions of i nitially-formed active stars. Thus intermolecular or star-star couplin gs are proposed to lead to higher order (secondary, tertiary, etc.) st ars, whereas intramolecular reactions result in core-contraction. The mechanism of these reactions has been outlined. The effect of PIB+ pre -arm length on star-star coupling was analyzed.