Novel multi functional polymers by metathesis polymerization

Abstract

A new class of thermotropic side-chain liquid crystalline polymers containing poly(1,6-heptadiyne) main chain was prepared by metathesis polymerization with transition metal catalysts. It was found that the $MoCl_5$-based catalyst systems were very effective for the polymerization of presently investigated monomers. Structure of the product was confirmed by spectral data. Polymerization of dipropargyl derivatives give to a conjugated polyene that contains both five-and six-membered ring incorporated into the polyene backbone. Resulting polymers with electron donating mesogenic group exhibited good solubility in common organic solvents and could be easily cast on glass plates to give black shiny thin films. However, polymers containing mesogenic groups with hetero atoms were partially soluble in common organic solvents. Copolymerization of diethyl dipropargyl malonate with presently monomers was attempted by various transition metal catalysts. The solubility of the resulting copolymers was increased as the feed ratio of DEDPM was increased. The number average molecular weight($\overline{Mn}$) values of the polymers were in the range of $0.49\sim18＼times10^4$ relative to polystyrene standards by GPC. Thermal behavior, morphology, and electrical conductivity were investigated by using optical polarized microscopy, X-ray diffraction analysis, and LCR meter. Room temperature conductivities of the undoped and $I_2$-doped polymers were found to be about $10^{-12}$ S/cm and $10^{-4}\sim10^{-2}$ S/cm, respectively. Both monomers and polymers displayed enantiotropic liquid crystallinity showing the reversible phase transitions.