RESUMO
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.
Assuntos
Acrilatos/química , Cristais Líquidos/química , Polímeros/química , Compostos de Sulfidrila/química , Eletricidade , Luz , Microscopia Eletrônica de Varredura , Estrutura Molecular , Fenômenos ÓpticosRESUMO
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.
Assuntos
Acrilatos/química , Cristais Líquidos/química , Polímeros/química , Compostos de Sulfidrila/química , Óptica e Fotônica , Processos Fotoquímicos , Polimerização , Raios UltravioletaRESUMO
A novel light diffuser based on a thermally cured polymer dispersed liquid crystal (PDLC) film was facilely fabricated by the thermal curing of epoxy monomers with thiols and polyamine (PA) in a composite solution of monomers and liquid crystals (LCs) sandwiched by two clean polyethylene terephthalate (PET) substrates. Varied amounts of LCs, diluent effects of epoxy resins and thiols and different curing temperatures have been investigated in the preparation of the films, and the optical properties (total transmittance and transmittance haze) and the light diffusing abilities of these films were also studied. As the microstructures of the polymers in the films were analysed using light scattering theory, it was revealed that the total transmittance of the novel light diffuser, with a combined polymer morphology of polymer networks and polymer balls, can reach 93% by simultaneously possessing a high transmittance haze (95%). The novel light diffuser, based on thermally cured PDLCs, possesses a good diffusion capacity and will have promising potential applications in military projects and liquid crystal display (LCDs) devices.
RESUMO
Using a quite small but suitable amount of Nafion as stabilizer, iridium colloids with well controlled particle size were synthesized and directly used for fuel cells or water electrolyzers without further removal or addition of Nafion, meanwhile, a strategy for fabrication of supported catalyst with high utilization was also proposed.