Construction of Functional Materials in Various Material Forms from Cellulosic Cholesteric Liquid Crystals

Abstract

Wide use of bio-based polymers could play a key role in facilitating a more sustainable society because such polymers are renewable and ecofriendly. Cellulose is a representative bio-based polymer and has been used in various materials. To further expand the application of cellulose, it is crucial to develop functional materials utilizing cellulosic physicochemical properties that are acknowledged but insufficiently applied. Cellulose derivatives and cellulose nanocrystals exhibit a cholesteric liquid crystal (ChLC) property based on rigidity and chirality, and this property is promising for constructing next-generation functional materials. The form of such materials is an important factor because material form is closely related with function. To date, researchers have reported cellulosic ChLC materials with a wide range of material forms—such as films, gels, mesoporous materials, and emulsions—for diverse functions. We first briefly review the fundamental aspects of cellulosic ChLCs. Then we comprehensively review research on cellulosic ChLC functional materials in terms of their material forms. Thus, this review provides insights into the creation of novel cellulosic ChLC functional materials based on material form designed toward the expanded application of cellulosics.

Recent Advances and Opportunities for Cellulose Nanocrystal-Based Liquid Crystalline Polymer Hybrids and Composite Materials

“…This serves to overcome the handling difficulties and slow stimuli responses of highly viscous cellulosic cholesterics. It is worth noting that the unique characteristic physical properties of fabricated materials cannot be observed in a bulk liquid crystal because this technique involves confining the liquid crystal phase in a microscopic droplet . Some of these intriguing characteristics include high macroscopic and high stimuli responsivity originating from the large surface area of the microscopically dispersed liquid crystal phase …”

“…The development of liquid crystal emulsions as a system composed of a liquid crystal phase and a continuous phase creates an excellent potential for liquid-type cholesteric functional materials that can easily be functionalized through hydrogen bonding and electrostatic forces. 51 This serves to overcome the handling difficulties and slow stimuli responses of highly viscous cellulosic cholesterics. It is worth noting that the unique characteristic physical properties of fabricated materials cannot be observed in a bulk liquid crystal because this technique involves confining the liquid crystal phase in a microscopic droplet.…”

Cellulose through the Lens of Microfluidics: A Review

“…CNCs in liquid crystalline form are materials that are both a hybrid of long-range organized structure belonging to crystal structure and mobility that can create an isotropic liquid. Among the several varieties of liquid crystals, cholesteric liquid crystals [262] are popular because they are one-dimensional photonic crystals with a photonic band gap (PBG) structure due to their helical structure. These materials have opalescent hues when the half value of the helical pitch length is the same size as the wavelength of visible light.…”

Colorimetric Sensor Based on Hydroxypropyl Cellulose for Wide Temperature Sensing Range

“…Although the underlying physical mechanism remains unclear, this characteristic is supposed to result from ethylene glycol, affecting the hydrogen-bonding system between the HPC and the solvent. HPC molecules are self-assembled to form a cholesteric liquid-crystalline structure by forming a hydrogen bond network with water molecules [ 25 ]. In this process, it is assumed that the modulation with ethylene glycol is correlated with the properties of the cholesteric liquid-crystalline structure, such as helical pitch, and the properties of the HPC solution, such as phase separation.…”