Preparation of Highly Durable Reverse-Mode Polymer-Stabilized Liquid Crystal Films with Polymer Walls

Reverse-mode polymer-stabilized liquid crystal (PSLC) films have wide applications in smart windows for cars as well as buildings and dimming glasses due to their low haze, low energy consumption, and better safety in case of emergency power off. However, PSLC films usually have poor stability of electro-optical properties due to their low polymer content (ca. 5 wt %), and it still remains a challenging task to improve the stability and processability by increasing the polymer content in PSLC as the driving voltage might dramatically increase. In this work, a reverse-mode PSLC film with polymer walls was prepared, which showed excellent stability of electro-optical properties even after 150 000 cycles. The film was prepared through polymerization with a photomask, in which the monomers concentrated on specific areas to form patterned polymer walls. In this way, the polymer content could be increased dramatically and the anchoring effect would not be too strong, thus avoiding a sharp increase in the driving voltage. As a result, the desired reverse-mode film with high stability, relatively low driving voltage, and high contrast ratio was obtained. The effects of monomer compositions, curing temperature, UV light intensity, and the pattern of the photomask on the microstructures, as well as electro-optical performances of the films were carefully studied. This work provides a new idea for the preparation of reverse-mode electrically switchable light-transmittance controllable films with excellent stability and good electro-optical performance, which would broaden their application in smart cars, building windows, and dimming glasses for light management and potential energy saving.