SYNTHESIS AND PROPERTIES OF BLOCK POLYMERS .I. POLY-ALPHA-METHYLSTYRENE-POLYISOPRENE-POLY-ALPHA-METHYLSTYRENE

Block polymers of polystyrene-polyisoprene-polystyrene (SIS) and poly-α-methylstyrene-poly-isoprene-poly-α-methylstyrene (mSImS) have been synthesized using 1,4-dilithio-1, 1,4,4-tetraphenylbutane as the initiator. Unlike previous dilithium initiators this species is capable of generating polyisoprene whose microstructure retains the high (>90%) 1,4 character necessary for elastomeric behavior. Furthermore, molecular weight measurements indicate that this initiator is capable of synthesizing block polymers possessing predictable molecular weights and narrow molecular weight distributions. Measurements of the tensile strength of SIS and mSImS block polymers of virtually identical composition and molecular weight shows that the replacement of polystyrene with poly-α -methylstyrene endows the mSImS block polymer with higher tensile strengths at comparable temperatures as well as higher temperature capability. © 1969, American Chemical Society. All rights reserved.