SYNTHESIS AND CHARACTERIZATION OF POLY[(2,6-DIMETHYL-1,4-PHENYLENE OXIDE)-BLOCK-ISOPRENE] DIBLOCK COPOLYMERS

As a first stage in the synthesis of a new class of thermoplastic elas tomers, a suitable synthetic route for elastomeric tailor-made diblock copolymers based on poly(2,6-dimethyl-1 ,4-phenylene oxide), PPE, as the thermoplastic block and on 1,4-polyisoprene, PIP, as the elastomer ic block, is outlined. The 2,6-dimethyl-1,4-phenylene oxide-block isop rene diblock copolymers were synthesized via an amidation coupling rou te between the ammonium salt of PPE and the monocarboxylic acid of PIP in the presence of dicyclohexylcarbodiimide, DCC. Preliminary studies were focused on the synthesis of a well-defined low molar mass dibloc k copolymer (<(M)over bar(n)> = 10000) in order to facilitate the quan titative characterization by proton NMR spectroscopy. The developed am idation coupling route was successively applied to the synthesis of a similar diblock copolymer with a number-average molar mass of 40 000 i n order to obtain optimum overall properties.