Effect of doped SiO 2 microspheres on the high temperature properties of PDLC films

Polymer-dispersed liquid crystal (PDLC) films are electrically controlled dimming films. By applying an electric field to the PDLC film, it becomes transparent, whereas in the absence of an electric field, the PDLC film is opaque. In recent years, with the development of new-energy vehicles, the utilisation of glass curtains instead of the conventional skylight or sunshade has become a trend, because the combination of PDLC films and glass can realise random switching between shading and transparency; thus, it has great application prospects in the automotive industry. However, the low operating temperature of PDLC films limits their application. In this study, a characterisation method for PDLC film performance at high temperatures is discussed, and the effect of SiO2 microspheres on the high-temperature properties of PDLC films is investigated. When the proportion of doped SiO2 was 1.5%, the maximum operating temperature reached 95°C, and the light transmittance and hazeon (power on) did not change compared with the PDLC film without doped SiO2. The utilisation of the power-off haze at high temperature as a performance index of PDLC films has universal significance for the evaluation of the high-temperature resistance of these materials.