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

Kotni, Ramakrishna; Grau-Carbonell, Albert; Chiappini, Massimiliano; Dijkstra, Marjolein; van Blaaderen, Alfons · Nat Commun · 2022

basic_science · Level V

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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<sub>TB</sub>) and splay-bend (N<sub>SB</sub>) nematic phases. Here, we show experimentally that the elusive N<sub>SB</sub> phases can be stabilized in systems of polydisperse micron-sized bent silica rods. Our results open avenues for the realization of N<sub>TB</sub> and N<sub>SB</sub> phases of colloidal and molecular LCs.