ABSTRACT
Zelinski and his co-workers in the Phillips laboratory have conducted an extensive program on copolymerization of butadiene and styrene in solution with alkyllithium from 1957 on. In this program, these researchers discovered the synthesis of tapered block copolymers and random copolymers using polar compounds as adjuvent to cause the randomization [1,2]. In 1960, Crouch of Phillips Petroleum Company reported briefly at the Second International Synthetic Rubbery Symposium held in London on a copolymer produced in pilot plant reactors for market development study [3]. This copolymer, Solprene 1205 rubber, was the first solution block copolymer of butadiene and styrene produced commercially [4]. It is a block copolymer containing 75 parts butadiene and 25 parts styrene. It is useful in many applications and has unique properties not found in styrenebutadiene rubber (SBR) types [5]. Another solution copolymer, Solprene 1204 rubber, of butadiene and styrene was offered in commercial quantity by Phillips 1 year later [6]. Solprene 1204 copolymer is random copolymer. The polymerization chemistry and properties of these two types of copolymers were reported by Hsieh at the Fourth International Synthetic Rubber Symposium held in London in 1964 [7]. Both Solprene 1205 and 1204 copolymers are no longer produced in the
some 110°C above its glass transition temperature. The block copolymers exhibits both glass transitions when taken through the —100-150°C range.
