Poly(4-vinylpyridine)-based hydrogen bonded side-chain liquid crystal polymers

Novel liquid crystalline (LC) poly(4-vinylpyridine) (PVP)-based side-chain polymers were prepared from PVP and cyanobiphenyl (HOCnB) derivatives through intermolecular hydrogen-bonding between hydroxyl groups of the cyanobiphenyl derivatives and the nitrogen of PVP. PVP was used as a hydrogen bond acceptor polymer. A series of HOCnB having a linear alkoxy chain HOCnH2n + 1O-(n = 2-6) have been used as H-bond donor. The existence of H-bonding was confirmed using FTIR spectroscopy. The polymeric complexes behave as LC polymers and exhibit stable mesophases. DSC and optical microscopy were used to investigate LC behaviour. All PVP-LC-complexes exhibited stable and homogeneous nematic phases. On increasing spacer length or concentration of the hydrogen bonded mesogenic unit in the complex, the clearing temperature and the temperature range of the nematic phase increased. The binary phase diagram of the polymeric complexes PVP-HOCnB showed complete miscibility over the entire range of composition. Molecular interactions of self-assembled SCLCP presented the idea that various LC-complexes could be prepared through mixing a functionalised polymer with various low molar mass mesogens.