In this paper, dye-doped polymer-dispersed liquid crystalline (DDPDLC) films were prepared with high mechanical properties and low driving voltage by doping different dichroic anthraquinone dyes. The effects of various dye and doping concentrations on microscopic morphology, electro-optical characteristics, and mechanical characteristics were investigated. The optimal doping concentrations of different dyes were also explored. The results show that the addition of all dyes decreased the contrast ratio (CR) and the transmittance and mechanical properties of the polymer-dispersed liquid crystalline (PDLC) films. Similar mechanisms underlie the effects of solvent red 111 and solvent blue 104, which lower the driving voltages of the PDLC films. With the increasing concentration of the dye, the haze of the films first decreased and then increased after the content of the dye reached a certain level. For PDLC films doped with solvent green 28, the driving voltage and haze increased with the increasing content of the dye. According to different influencing factors, the dye content corresponding to the best performance of solvent red 111, solvent green 28 and solvent blue 104 is 0.8 wt%, 2.0 wt% and 0.3 wt%. Electrochromic PDLC films have been prepared based on the research results of dye content. The mechanical properties, electro-optical properties and microstructures of the films have been studied. The results show that the DDPDLC films could change color by tuning the applied voltages. The research provides a theoretical basis for obtaining PDLC films with a wider color gamut and supports the practical application of visible light camouflage technology in the military.

With the switchability between transparent and light-scattering states, polymer-dispersed liquid crystals (PDLC) are widely used as smart windows, flexible display devices, projectors, and other devices. In outdoor applications, in addition to excellent electro-optical properties, there is also a high demand for film stability. In this work, a PDLC film with high mechanical strength and structural stability is prepared that can maintain stability at 80 °C for 2000 h. By choosing liquid crystals with a wide temperature range, adopting acrylate polymer monomers containing hydroxyl groups, and adjusting the polymer content, the PDLC film can work well from −20 °C to 80 °C. On this basis, the effects of the introduction of rigid monomers on the mechanical properties and electro-optical properties of PDLC films are investigated.

In this work, hydroxylated compounds are applied to prepare polymer-dispersed liquid crystal (PDLC) films and the role of the hydroxy group is studied in detail by comparing the effects of the hydroxylated acrylate monomer, the hydroxylated mesogenic component and their corresponding non-hydroxylated components. It is revealed that the hydroxylated acrylate monomer plays a more important role in modifying the morphology of the polymer matrix and thereby the electro-optical performance of the PDLC films. Parameters of the polymer matrix, such as size and density of voids, can be affected by various components, but only the hydroxylated acrylate monomer can alter its type from the typical Swiss-cheese type to the polymer-microsphere type. Essentially, the hydroxylated mesogenic component takes effect through changing the ratio of the liquid crystal phase, while the hydroxylated acrylate monomer can participate in the polymerization and impact the development of the polymer matrix. It is anticipated that this research can help in understanding the role of the hydroxy group in PDLC films.

In this paper, a polymer dispersed liquid crystal (PDLC) film with good electro-optical properties and wide working temperature range was prepared by the UV-polymerization induced phase separation (PIPS) method by optimizing the curing temperature using a LC with wide temperature range. The investigation found that when the polymerization temperature was at the clearing point of the prepolymer/LC mixture, the film had better electro-optical properties and a high contrast ratio of 51 at 90 °C, and the rise time and decay time were respectively as fast as 241.5 ms and 1750 ms at −20 °C. This study provides further methodological guidance for the curing process of PDLC film, and promotes its application in outdoor smart windows.