Bromination of some styrene-diene block copolymers

The bromine addition at the polydiene block double bonds of a radial styrene-butadiene (SBS) and a linear styrene-isoprene (SIS) block copolymer (thermoplastic elastomers), in tetrahydrofurane solution at 0 degrees C, has been investigated by IR spectroscopy. In both cases the bromine reacts exclusively with the polydiene middle block double bonds; the polystyrene blocks are unaffected. The bromine reacts preferentially with the 1,4-type (cis and trans) double bonds of the polybutadiene block of SBS. At low bromination level (below 5%) the bromine reacts mainly with the 1,4-cis type double bonds of polyisoprene block of SIS, while at higher bromination level the bromine presents the same reactivity towards the 1,4-type (cis and trans) and vinylic (3,4-type) double bonds. (C) 1997 Elsevier Science Ltd.