Chiral polymer networks with a broad reflection band achieved with varying temperature

In this study, we demonstrate a novel method for fabricating a single layer cholesteric liquid crystal (CLC) film with non-uniform pitch distribution by utilizing the chiral polynetworks. A chiral monomer, the helical twist power (HTP) of which decreases with the increase of temperature, was synthesized. The temperature dependence of the pitch of the mixtures before and after polymerization was investigated. To broaden the reflection band, the experimental processes of thermally induced pitch variation were presented. The results suggest that the chirality of the polymer network plays an integral role in the reflection spectra. Additionally, scanning electron microscopy (SEM) was used to examine the role of the polymer network induced by polymerization temperature. These wide-band reflection optical properties make the CLC gels interesting for their potential applications in many fields, such as colour filters, brightness enhancement films, smart switchable reflective windows etc.