BROMINATION OF SOME STYRENE-DIENE BLOCK-COPOLYMERS

The bromine addition at the polydiene block double bonds of a radial s tyrene-butadiene (SBS) and a linear styrene-isoprene (SIS) block copol ymer (thermoplastic elastomers), in tetrahydrofurane solution at 0 deg rees C, has been investigated by IR spectroscopy. In both cases the br omine reacts exclusively with the polydiene middle block double bonds; the polystyrene blocks are unaffected. The bromine reacts preferentia lly with the 1,4-type (cis and trans) double bonds of the polybutadien e 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 SI S, while at higher bromination level the bromine presents the same rea ctivity towards the 1,4-type (cis and trans) and vinylic (3,4-type) do uble bonds. (C) 1997 Elsevier Science Ltd.