Stable soft cubic superstructure enabled by hydrogen-bond complex functionalized polymer/liquid crystal system

Abstract

A stable liquid crystal soft cubic superstructure (i.e., blue phase) in a wide temperature range was achieved by photopolymerizing a judiciously designed hydrogen-bond (H-bond) complex functionalized polymer/liquid crystal system. Such an H-bond is generated through complexation between a polymerizable proton acceptor and a mesogenic proton donor, which plays a positive role in structural enhancement of a blue phase on one hand, and on the other hand enables the stabilization of such a cubic superstructure with a lower polymer content compared with that of conventional materials. Owing to the two aforementioned aspects, the driving voltage of such a system was reduced significantly, while a fast responsiveness of the blue phase (i.e., submillisecond) was still maintained. A noteworthy aspect is that a weak electro-optical hysteresis of such blue phases, which is generally generated in a high polymer content system, has been achieved herein in a low polymer content system, due to the H-bond interaction between the mesogenic donor and the proton acceptor decorated polymer network. Herein, a stable blue phase II with a wide temperature range from 55.3 °C, spanning the whole room temperature range, to a temperature lower than −40 °C was obtained, and moreover its electro-optical performances at −15 °C were demonstrated. This work develops a new approach to stabilize a soft cubic superstructure with satisfying thermal and electro-optical performances, which may be a promising candidate or competitor with regards to conventional materials, thereby facilitating its practical applications in diverse perspective fields.