POLYETHYLENE DIBLOCK COPOLYMERS - DIRECT SYNTHESIS AND MORPHOLOGICAL ANALYSIS

Polystyrene and polybutadiene were block copolymerized with high density polyethylene using a transformation reaction from an anionic to a Ziegler-Natta type polymerization. Various reaction parameters were investigated and optimized. Efficiencies of conversion of the anionic block to diblock were as high as 33% (100% normalized) consistent with the known 3/1 Li-R/Ti relationship in the active catalyst species. The activity of the polymeric Li-R/Ti catalyst with regards to ethylene polymerization was as high as 40 000 grams of polymer/mole Ti. Characterization of the resultant polymers is consistent with diblock copolymer structures but transmission electron microscopy shows distinct differences between the morphological behavior of these materials and the now well established morphological behavior of amorphous-amorphous diblock copolymers. These differences are readily explained by consideration of the interactions between the competing thermodynamic processes of microphase separation and crystallization.