POLYETHYLENE DIBLOCK COPOLYMERS - DIRECT SYNTHESIS AND MORPHOLOGICAL ANALYSIS

Polystyrene and polybutadiene were block copolymerized with high densi ty polyethylene using a transformation reaction from an anionic to a Z iegler-Natta type polymerization. Various reaction parameters were inv estigated and optimized. Efficiencies of conversion of the anionic blo ck to diblock were as high as 33% (100% normalized) consistent with th e known 3/1 Li-R/Ti relationship in the active catalyst species. The a ctivity of the polymeric Li-R/Ti catalyst with regards to ethylene pol ymerization was as high as 40 000 grams of polymer/mole Ti. Characteri zation of the resultant polymers is consistent with diblock copolymer structures but transmission electron microscopy shows distinct differe nces between the morphological behavior of these materials and the now well established morphological behavior of amorphous-amorphous dibloc k copolymers. These differences are readily explained by consideration of the interactions between the competing thermodynamic processes of microphase separation and crystallization.