Synthesis, photophysical properties and microphase separation of all-conjugated diblock copolymers with hydrophilic side chains

摘要

A series of new all-conjugated diblock copolymers, poly(2,5-dioctyloxy-p-phenylene)-block-poly(3-methoxyethoxyethoxy-methylthiophene) (PPP-b-P3MEEMT), with hydrophilic side-chains have been synthesized by quasi-living Grignard metathesis polymerization. The narrow polydispersity indices of the block copolymers are in the range 1.32-1.40. The block ratios in the obtained diblock copolymers can be well defined by the feed ratios of the monomers. Photoluminescence results reveal that resonance energy transfer occurs from the PPP block to the P3MEEMT block in dilute solution. Differential scanning calorimetry shows that both PPP and P3MEEMT blocks in the copolymers produce crystalline regions and lead to microphase separation as indicated by two endothermal transitions, corresponding to the melting peaks of the PPP and P3MEEMT blocks, respectively. The formations of microphase-separated nanostructures in annealed copolymer films are also observed using transmission electron microscopy.