Functional polydiynes prepared by metathesis cyclopolymerization of 1,7-dihalogen-1,6-heptadiyne derivatives

We report the metathesis cyclopolymerization (MCP) of 1,7-dihalogen-1,6-heptadiyne derivatives by using MoCl5/(n-Bu)(4)Sn complex catalyst system. Five homopolymers (P1-P5) and a copolymer (P[1-co-5]) were obtained in high yields (up to 95%) with high molecular weights (M-w up to 210 000) under the optimized conditions (60 & DEG;C, 12 h, in 1,2-dichloroethane). The structures of the resultant polymers were characterized by FTIR, H-1 NMR, C-13 NMR and UV-vis spectroscopic techniques, which confirmed the MCP methodology was successfully applied to the preparation of halogen-modified polydiynes. The resultant polydiynes possess good solubility in common organic solvents and high thermal stability. More significantly, these chloro-modified polydiynes demonstrated unprecedented upper critical solution temperature (UCST) behavior, which can be tentatively related to the halogen bonding between the halogen atoms and the oxygen/nitrogen atoms of solvents. The UCST performance of the polydiynes was influenced by the side chain of the polymers (58-110 & DEG;C) and copolymerization of different monomers (61-66 & DEG;C). Interestingly, by linking tetraphenylethene (TPE) groups onto the polymer side chains, the UCST process could be visually monitored due to the aggregation-induced emission characteristics of TPE groups.