Switchable smart windows using a biopolymer network of cellulose nanocrystals imposed on a nematic liquid crystal

Abstract

A polymer stabilized liquid crystal (PSLC) system formed by a nematic contained in a biopolymer network of cellulose nanocrystals, exhibiting many attractive features, is demonstrated. The threshold or the minimum voltage needed to operate the electro-optic device does not depend on the concentration of the polymer, a feature that is in contrast to the standard PSLC systems. A second point, more important from the driving circuit point of view, is that the voltage-off response time drastically reduces and even becomes practically invariant over the thermal range of the nematic phase. A smart window fabricated using this biopolymer network system exhibits good contrast between the scattering and transparent states driven by voltage and shows an exceptionally high haze factor. A highlight of the device fabrication is that the employed protocol is facile, making it appealing for a potentially viable smart window application.