Strongly Chiral Liquid Crystals in Nanoemulsions

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2022-03, Vol.18 (10), p.e2105835-n/a
• Main Authors: Yang, Yu, Palacio‐Betancur, Viviana, Wang, Xin, Pablo, Juan J., Abbott, Nicholas L.
• Format: Article
• Language: English
• Subjects: blue phases; confinement; Droplets; Emulsions; light scattering; Liquid crystals; Nanoemulsions; Nanotechnology; Phase transitions; Simulation
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202105835

Liquid crystal (LC) emulsions represent a class of confined soft matter that exhibit exotic internal organizations and size‐dependent properties, including responses to chemical and physical stimuli. Past studies have explored micrometer‐scale LC emulsion droplets but little is known about LC ordering within submicrometer‐sized droplets. This paper reports experiments and simulations that unmask the consequences of confinement in nanoemulsions on strongly chiral LCs that form bulk cholesteric and blue phases (BPs). A method based on light scattering is developed to characterize phase transitions of LCs within the nanodroplets. For droplets with a radius to the pitch ratio (Rv/p0) as small as 2/3, the BP‐to‐cholesteric transition is substantially suppressed, leading to a threefold increase of the BP temperature interval relative to bulk behavior. Complementary simulations align with experimental findings and reveal the dominant role of chiral elastic energy. For Rv/p0 ≈ 1/3, a single LC phase forms below the clearing point, with simulations revealing the new configuration to contain a τ−1/2 disclination that extends across the nanodroplet. These findings are discussed in the context of mechanisms by which polymer networks stabilize BPs and, more broadly, for the design of nanoconfined soft matter. A method based on light scattering is developed to characterize the phase behavior of chiral liquid crystals confined in nanoemulsion droplets. The study reveals that confinement in nanodroplets leads to the suppression of the cholesteric‐to‐blue phase transition temperature, and the emergence of an exotic phase different from the bulk state.