MOLECULAR DESIGN OF MULTICOMPONENT POLYMER SYSTEMS: VII. EMULSIFYING EFFECT OF POLY(ETHYLENE-B-STYRENE) COPOLYMER IN HIGH-DENSITY POLYETHYLENE/POLYSTYRENE BLENDS.

Poly(butadiene-b-styrene) copolymers containing a pure 1,4-PB block have been synthesized by a 'living' coordination process. The complete hydrogenation of the PB chain leads accordingly to a high-density polyethylene (HDPE) block. The emulsifying efficiency of such a copolymer (H-7) in HDPE/PS blends is compared with that of a previously reported poly(ethylene-butene-b-styrene) copolymer (SE-7) obtained by the PB hydrogenation of an anionically prepared PB-b-PS. Microscopy examinations demonstrate unambiguously the interfacial activity of both copolymers in HDPE/PS blends. The tensile mechanical properties of the blends are significanty but also differently modified by the two emulsifiers. The copolymer H-7 gives rise to the highest strengths, but, contrary to the copolymer SE-7, provides a poor ductility to the blends.