Chiral Liquid Crystalline Properties of Cellulose Nanocrystals: Fundamentals and Applications

Abstract

By using an independent self-assembly process that is occasionally controlled by evaporation, cellulose nanocrystals (CNCs) may create films (pure or in conjunction with other materials) that have iridescent structural colors. The self-forming chiral nematic structures and environmental safety of a new class of photonic liquid crystals (LCs), referred to as CNCs and CNC-embedded materials, make them simple to make and treat. The structure of the matrix interacts with light to give structural coloring, as opposed to other dye pigments, which interact with light by adsorption and reflection. Understanding how CNC self-assembly constructs structures is vital in several fields, including physics, science, and engineering. To constructure this review, the colloidal characteristics of CNC particles and their behavior during the formation of liquid crystals and gelling were studied. Then, some of the recognized applications for these naturally occurring nanoparticles were summarized. Different factors were considered, including the CNC aspect ratio, surface chemistry, concentration, the amount of time needed to produce an anisotropic phase, and the addition of additional substances to the suspension medium. The effects of alignment and the drying process conditions on structural changes are also covered. The focus of this study however is on the optical properties of the films as well as the impact of the aforementioned factors on the final transparency, iridescent colors, and versus the overall response of these bioinspired photonic materials. Control of the examined factors was found to be necessary to produce reliable materials for optoelectronics, intelligent inks and papers, transparent flexible support for electronics, and decorative coatings and films.

Cellulose Nanocrystals Examined by Atomic Force Microscopy: Applications and Fundamentals

“…According to the authors, the asymmetric nanocrystalline arrangement of CNC permeated the monolithic films’ full thickness and covered a large surface area, producing intense iridescence and improved circular polarization . Circular polarization and intensity of iridescence are directly correlated to the development of liquid crystalline phases out of CNCs; a detailed account of the liquid crystal formation of CNCs can be found in ref .…”

Nanocellulose Product Design Aided by Confocal Laser Scanning Microscopy

“…CLSM can also be used to capture gel collapse; for instance, in one study, , it appears that yielding to gravity is influenced by CNC and salt, and the photographs taken here show a snapshot of the suspension between the almost initial period of gel creation ( t ∼5 min) and the extent of the gel after 25 min. Due to gravitational forces, the gel with lower CNC content has fallen to the bottom of the Petri dish, whereas the sturdier gel has maintained its structural integrity.…”

“…This technique (freeze–thaw) of gelation induces the CNC particles to go through physical gelation by cornering them with increasing ice crystals. A simple experiment to see if CNC particles gel after being annealed at high temperatures was carried out . CNC particles were annealed at high temperatures in an autoclave chamber to promote gelation.…”

“…CLSM has the benefit of being able to visualize the bulk structure of hydrogels without interfering with it before any examination. Without changing the structure, CLSM pictographs of the hydrogel bulk structure may be collected at predefined time increments; moreover, the cluster size of CNC particles can also be determined using CLSM . Imaging CNC particle aggregates similar to other aggregated structures usually comes with slight error in its estimation.…”

A road map on synthetic strategies and applications of biodegradable polymers

“…Because of its low-cost sustainability, non-toxicity, easy availability of raw ingredients simple manufacturing methods and low energy consumption. This innovative type of liquid crystals materials as the potential for commercial large-scale use [ 212 ].…”