A Bending-Resistant Epoxy PSLC Film with Ultrahigh Peel Strength via Well-Controlled Rapid Cationic Polymerization for Smart Window Applications

Abstract The polymer-stabilized liquid crystal (PSLC) dimming film has garnered widespread attention due to its energy-saving features and good electro-optical performance, making it highly suitable for smart windows in automotive and architectural applications. However, its poor mechanical properties severely limit its large-scale flexible film production and wide application due to its internal fine and fragile polymer network. Enhancing the processability and peel strength of PSLC films remains particularly challenging because electro-optical performance degrades rapidly with increasing polymer content. Herein, a PSLC film with ultrahigh peel strength and good electro-optical performance is attained through well-controlled rapid photopolymerization of epoxy monomers using photoinitiators 1173 and 1176. The polymerization time is greatly shortened from hours to a few minutes, and the polymer content of this composite film is increased to over 20 wt % by carefully controlling light intensity, photoinitiator, and monomer composition, while retaining good electro-optical performance. The peel strength and contrast ratio are improved by over 40 times and 3 times, respectively, compared to epoxy PSLCs prepared by normal cationic polymerization. The peel strength of this film is incredibly high, about 500 times that of a traditional PSLC device, and is even higher than those of some polymer-dispersed liquid crystal films. The cycle stability and thermal stability of PSLC films have also been significantly improved a lot. The dependence of monomer composition on the microstructures, electro-optical, and mechanical properties of the PSLC film has been systematically studied. This research provides a novel strategy for the fabrication of high-performance PSLC films toward next-generation energy-efficient smart windows.