Splay-bend nematic phases of bent colloidal silica rods induced by polydispersity

Abstract

Liquid crystal (LC) phases are in between solids and liquids with properties of both. Nematic LCs composed of rod-like molecules or particles exhibit long-range orientational order, yielding characteristic birefringence, but they lack positional order, allowing them to flow like a liquid. This combination of properties as well as their sensitivity to external fields make nematic LCs fundamental for optical applications e.g. liquid crystal displays (LCDs). When rod-like particles become bent, spontaneous bend deformations arise in the LC, leading to geometric frustration which can be resolved by complementary twist or splay deformations forming intriguing twist-bend (N_TB) and splay-bend (N_SB) nematic phases. Here, we show experimentally that the elusive N_SB phases can be stabilized in systems of polydisperse micron-sized bent silica rods. Our results open avenues for the realization of N_TB and N_SB phases of colloidal and molecular LCs.