Abstract
We have studied liquid crystals (LCs) and acrylate-assisted thiol-ene compositions to synthesize dye based colorful polymer dispersed liquid crystals (PDLCs) without using a photo-initiator for smart-windows applications. A typical PDLC mixture was prepared by mixing LCs with UV-curable monomers, which included triethylene glycol diacrylate (TEGDA), trimethylolpropane diallyl ether (TMPDE, di-functional ene monomer), trimethylolpropane tris(3-mercaptopropionate) (TMPTMP, a thiol as a cross-linker), and a dichroic dye. The ratios of the TMPDE/TMPTMP and the LCs/TEGDA showed significant effects in altering the properties of the UV-cured PDLCs. During the curing process, the monomers polymerize and led to the encapsulation of the LCs in the form of interesting fractal nanostructures by a polymerization induced phase separation process. The switching time, electro-optical properties, power consumption, and ageing of the fabricated PDLCs were investigated. It was possible to achieve a 70-80% contrast (ΔT) at a voltage difference of ∼70 V with a fast switching time (τ) as low as < 20 milliseconds (ms) and low power consumption. These PDLCs had a low threshold voltage that ranged between 10 and 20 V. The sustainability of the fabricated UV-cured PDLCs was analyzed for up to 90 days, and the PDLCs were observed to be stable.