SYNTHESIS OF DISCOTIC COLUMNAR SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERSBY RING-OPENING METATHESIS POLYMERIZATION (ROMP)

Discotic liquid crystalline polymers bearing alkoxy-substituted triphe nylene moieties in the side-chain were synthesized by ring-opening met athesis polymerization using a well-defined ruthenium initiator. To el ucidate the effect of backbone flexibility on the mesomorphism, norbor nene and cyclobutene monomers containing triphenylene moieties were sy nthesized, which yielded the relatively rigid poly(norbornene)s and th e more flexible poly(butadiene)s, respectively, after polymerization. To further increase the backbone flexibility, the poly(butadiene)s wer e hydrogenated using Crabtree's catalyst to yield triphenylene-substit uted poly(butane)s. The mesomorphic behavior of the polymers has been investigated by differential scanning calorimetry (DSC) and powder dif fraction X-ray scattering (wide angle X-ray scattering, WAXS). All pol ymers bearing a 2,3,6,7,19-pentakis(decyloxy)triphenylene-based mesoge nic unit exhibit enantiotropic discotic hexagonal mesophases, while th e pentoxy analogues do not display liquid crystalline behavior. No eff ect of backbone rigidity on the mesomorphism could be detected.