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 elastomers, 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 elastomeric block, is outlined. The 2,6-dimethyl-1,4-phenylene oxide-block-isoprene diblock copolymers were synthesized via an amidation coupling route 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 welldefined low molar mass diblock copolymer (M _n = 10000) in order to facilitate the quantitative characterization by proton NMR spectroscopy. The developed amidation coupling route was successively applied to the synthesis of a similar diblock copolymer with a number-average molar mass of 40000 in order to obtain optimum overall properties.