Flexible Amine-Acrylate-Based Polymer Stabilized Liquid Crystal Films toward Radiative Cooling Smart Windows

Polymer-stabilized liquid crystal (PSLC) dimming films have broad applications in smart windows due to their excellent electro-optical performance and normally transparent working mode. However, traditional PSLC films suffer from issues such as weak mechanical strength, difficulty in simultaneously optimizing electro-optical performance and mechanical properties, and insufficient near-infrared light shielding ability. In this study, an amine-acrylate-based PSLC system has been constructed based on the Aza-Michael addition reaction, and the effects of polymerization conditions and carbon chain length of diamine on the electro-optical performance, interfacial peel strength, microstructures, and spectral regulation ability have been systematically investigated. The results show that the amino-acrylate PSLC reaches a maximum contrast ratio of 193.52, which is about 5 times higher than that of the pure acrylate system. Amino modification increases the film peeling strength by 2 to 3 times compared to the pure acrylate system, with the longest carbon chain amine system achieving a peeling strength of 128.38 kPa. The film also possesses good passive radiative cooling performance due to the abundant C-F/C-N/N-H bonds in liquid crystals and polymer networks, with a maximum cooling power of 132.34 W/m2 at night and 82.85 W/m2 during the day, lowering temperatures by 8.45 and 14.04 °C in the off/on states relative to the environment. Actual working condition verification indicates that the miniature room equipped with amino-acrylate PSLC film could achieve a maximum temperature decrease of 4.11 °C compared to the miniature room equipped with ITO glass. These results indicate that the introduction of flexible carbon chain with an amino group into the rigid chain-based PSLC films endows the film with better electro-optical performance, higher peel strength, and improved radiative cooling ability. This study provides a feasible route for the preparation of high-performance flexible reverse-mode dimming films and lays the foundation for its application in smart windows with radiative cooling.