Effects of rigid cores and flexible tails on the phase behaviors of polynorbornene-based mesogen-jacketed liquid crystalline polymers

A new series of mesogen-jacketed liquid crystalline polymers (MJLCPs) with a polynorbornene main chain and different side groups were prepared by ring-opening metathesis polymerization. The liquid crystalline (LC) phase behaviors of these polymers were investigated by differential scanning calorimetry, polarized light microscopy, and wide-angle X-ray diffraction. Depending on the rigid side-chain core and peripheral alkyl chains, these polymers show different LC structures. The polymer with the terphenyl rigid side-chain core and relatively short alkyl tails is amorphous in the whole temperature range, while those with the same rigid side-chain core but longer alkyl tails exhibit columnar nematic (Coln) phases. Polymers with a longer rigid side-chain core and relatively long alkyl tails develop into smectic A (SmA) phases. In addition, the LC polymers obtained in this study display LC phases in wide temperature ranges.