A series of siloxane-based liquid-crystalline (LC) elastomers were synthesized by using chemical crosslinking agents containing sulfonic acid groups. The crosslink densities of the elastomers were determined by swelling experiments. Two kinds of melting temperature corresponding to crystallization of siloxane matrix and crystallization of LC segments were clearly detected. Some of the polymers exhibited smectic mesophase textures or cholesteric mesophase textures. A proposed model containing LC segment structure and ionic crosslinking lamellar structure separated by siloxane chains was given. The ion aggregated in domains forces the siloxane chains to fold and form an irregular lamellar structure. Ionic aggregates and LC segments may be dispersed each other to form multiple blocks with increasing ionic crosslinking content.

The synthesis of the two monomers M1 and M2 and a series of new side-chain cholesteric liquid crystalline elastomers P2-P8 is presented. The chemical structures of the monomers and elastomers obtained were confirmed by FTIR or 1H NMR spectroscopy. The cross-link density of the elastomers was determined by swelling experiments. The mesomorphic properties were investigated by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. Monomer M1 showed a cholesteric phase, and M2 revealed smectic and nematic phases. The effect of the cross-link density on the phase behavior of P2-P8 is discussed. Elastomers P2-P6 containing less than 12mol % of the cross-linking units displayed elasticity, reversible liquid crystalline phase transition, wide mesophase temperature ranges, and high thermal stability. Elastomer P7 displayed stress-induced birefringence, and P8 showed only elasticity with no other texture. Experimental results demonstrated that the glass transition temperatures increased, and the isotropization temperatures and the mesophase temperature ranges of P2-P6 decreased with increasing cross-link density.

A series of ionic liquid-crystalline (LC) elastomers were synthesized by using chemical crosslinking agents containing sulfonic acid groups, which were siloxane-based materials. A ionic divinyl monomer 2,2¢-(1,2-ethenediyl)bis[5-[(4-undecenoyloxy)phenyl]azo]benzenesulfonic acid was used as chemical cross-linking agent. Cholest-5-en-3-ol(3β)-10-undecenoate was synthesized as a liquid-crystalline monomer. The effective cross-link density of the ionic elastomers was determined by swelling experiments in organic/buffer mixtures. Their liquid-crystalline properties were characterized by DSC, POM, and SAXS. A proposed multilayer buildup containing LC segment structure and ionic cross-linking lamellar structure separated by siloxane chains was given. The ion aggregated in domains forces the siloxane chains to fold and form an irregular lamellar structure. The ionic cluster lamellae may be tangled with the rigid mesogenic groups of LC segments to form multiple blocks. Liquid-crystal mesophase region of the polymers become narrow with increasing ionic cross-linking content.

The miscibility and mechanical properties of the blends of polybutylene terephthalate (PBT) and polypropylene (PP) with a liquid crystalline ionomer (LCI) containing a sulfonate group on the terminal unit as a compatibilizer were assessed. SEMand optical microscopy (POM) were used to examine the morphology of blends of PBT/PP compatibilized by LCI. DSC and TGA were used to discuss the thermal properties of PBT/PP blends with LCI and without LCI. The experimental results revealed that the LCI component affect, to a great extent, the miscibility and crystallization process and mechanical property of PBT/PP blends. The fact is that increasing LCI did improve miscibility of PBT/PP blends and the addition of 1%LCI to the PBT/PP blends increased the ultimate tensile strength and the ultimate elongation.

A new series of network liquid crystal polymers were synthesized by graft copolymerization of the difunctional mesogenic monomer 4-allyloxy-benzoyloxy-4'-allyloxybiphenyl (M) upon polymethylhydrosiloxane (PMHS). MonomerMacted not only as a mesogenic unit but also as a crosslinker for the network polymers. The chemical structures of the polymers were confirmed by IR spectroscopy. DSC, TGA, and X-ray scattering were used to measure their thermal properties and mesogenic properties. The glass transition temperature (Tg) of these network liquid crystal polymers was increased when the monomer was increased, and Td (temperature of 5%weight loss) at first went up and reached a maximumat P1, then went down. The slightly crosslinked polymers (P0, P1) show rubber-like elasticity, so it was called liquid-crystal elastomer. Network polymers will lose elasticity property with a highly crosslinked degree, and turn into thermosetting polymers (P4, P5). All polymers exhibited a smectic texture by X-ray scattering.