Organosilicon polymer materials play an important role in certain applications due to characteristics of much lower glass transition temperatures (T_g), viscosities, surface energy, as well as good mechanical, thermal stabilities, and insulation performance stemming from the higher bond energy and the larger bond angles of the adjacent silicon-oxygen bond. This critical review highlights developments in the synthesis, structure, and phase transition behaviors of polysiloxane-based side chain liquid crystal polymers (PSCLCPs) of linear and cyclic polysiloxanes containing homopolymers and copolymers. Detailed synthetic strategies are elaborated, and the relationship between molecular structures and liquid crystalline phase transition behaviors is systematically discussed, providing theoretical guidance on the molecular design of the materials.

Polymer-dispersed liquid crystal (PDLC) films were prepared by the ultraviolet-light-induced polymerization of photopolymerizable monomers in nematic liquid crystal/chiral dopant/thiol-acrylate reaction monomer composites. The effects of the chiral dopant and crosslinking agents on the electro-optical properties of the PDLC films were systematically investigate. While added the chiral dopant S811 into the PDLC films, the initial off-state transmittance of the films was decreased. It was found that the weight ratio among acrylate monomers, thiol monomer PETMP and the polymercaptan Capcure 3-800 showed great influence on the properties of the fabricated PDLC films because of the existence of competition between thiol-acrylate reaction and acrylate monomer polymerization reaction. While adding polymercaptans curing agent Capcure 3-800 with appropriate concentration into the PDLC system, lower driven voltage and higher contrast ratio were achieved. This made the polymer network and electro-optical properties of the PDLC films easily tunable by the introduction of the thiol monomers.

In this study, a polymer dispersed cholesteric liquid crystal (PDChLC) film obtained via a one-step fabrication technique based on photopolymerization of a thiol-acrylate reaction system was prepared and characterized for the first time. The effects of the chiral dopant, the influence of thiol monomer functionality and content on the morphology and subsequent performance of the PDChLC films were systematically investigated. It was demonstrated that the addition of a small amount of chiral dopant slightly increased the driving voltage, but decreased the off-state transmittance significantly. Furthermore, scanning electron micrographs (SEM) shown that the liquid crystal (LC) droplet size decreased at first and then increased with the increasing amount of thiol monomer functionality, while increasing the thiol content increased the LC droplet size. Correspondingly, the electro-optical switching behavior was directly dependent on LC droplet size. By tuning the raw material composition, PDChLC film with optimized electro-optical performance was prepared.

In this paper, a series of novel active silicone–oligomers (PMDM) of high refractive index (RI) with dual reactive moieties (Si–H and S–H) synthesized by nonhydrolytic sol–gel condensation are reported for the first time. The RI of the oligosiloxane can be effectively increased from 1.55 to 1.65 by varying the feed ratio between methyldimethoxysilane (MDMS) and 3-mercaptopropylmethyldimethoxysilane (MMDS). Additionally, via “thiol–ene” click chemistry and the subsequent hydrosilylation reaction under a Pt catalyst, a transparent siloxane-polymer film with enhanced refractive index (1.59) and excellent thermal stability (T_5% = 381 °C) was facilely synthesized and characterized, which in turn effectively substantiated the reactivity of the dual reactive moieties in PMDM. Such active oligomers would be useful chemical intermediates and the easily processed materials have great potential in modern optical/photonic applications such as waveguides, lasers or light emitting diodes.

Epoxy polymer dispersed liquid crystal (PDLC) films based on ethyleneglycol diglycidyl ether (EGDE)/nematic liquid crystal (SLC1717) composites were prepared by ultraviolet-initiated cationic polymerisation using triphenylsulfonium hexafluoroantimonate (Ar₃S⁺SbF₆ ⁻) as the photoinitiator. The effect of the composition of the mixture and curing temperature on the microstructure of the polymer network and the electro-optical properties was investigated. It was found that the liquid crystal (LC) domain size of the polymer network could be regulated by adjusting the LC content and the curing temperature. The electro-optical properties of PDLC films could then be optimised.