Structural Transition in Liquid Crystal Bubbles Generated from Fluidic Nanocellulose Colloids

Abstract

The structural transition in micrometer-sized liquid crystal bubbles (LCBs) derived from rod-like cellulose nanocrystals (CNCs) was studied. The CNC-based LCBs were suspended in nematic or chiral nematic liquid-crystalline CNCs,w hich generated topological defects and distinct birefringent textures around them. The ordering and structure of the LCBs shifted from anematic to chiral nematic arrangement as water evaporation progressed. These packed LCBs exhibited as pecific photonic cross-communication property that is due to ac ombination of Bragg reflection and bubble curvature and size.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Self‐Assembled Nanorods and Microspheres for Functional Photonics: Retroreflector Meets Microlens Array

“…[51] Owing to the elastic interplay between cholesteric CNC and hydrophilic particle surface, the PS microsphere will deform the liquid crystal interfacial region and generate a nontrivial interfacial curvature with bend-splay orientation distortions around the PS surface. [46,52] However, in the bulk region which far away from PS microspheres, the CNCs are freely assembled with the bulk helix appear to be oriented normal to the film surface. [49] As a result, the spatial ordering of cholesteric matrix is distorted around the curved hydrophilic PS surface, with the CNC orientation takes on a planar arrangement to lower the anchoring energy, [48] leading to long-range periodic assembly in the bulk phase and a deformed helical organization at the CNC-PS interface, with these arrangements further arrested in solid film.…”

“…[28][29][30] Upon evaporation, colloidal CNC particles spontaneously self-assemble into a cholesteric liquid crystal phase above critical concentration and further vitrify into solid film that retain the original helical structure, thereby yielding vivid structural color with tunable photonic band gap. [31,32] Owing to the nanometer-sized building blocks and robust selfassembly process, cholesteric ordered CNC can serve as versatile platform for material templating, [33,34] nanoimprinting, [35][36][37][38] matrix scaffolding, [39][40][41][42] and colloid assembly, [43][44][45][46] which can allow the construction of hierarchical photonic structures with precisely controlled light-matter interactions.…”

Printing Flowers? Custom-Tailored Photonic Cellulose Films with Engineered Surface Topography

“…Compared with pure CNC dispersion, CNC-PVA ink had several advantages such as adjustable helical pitch in cholesteric phase and excellent wettability on PDMS due to the reduced surface tension. 31,32 After drying under ambient conditions, colorful cholesteric composite films were obtained and peeled off, resulting in freestanding iridescent CWFs (Figure S5). Moreover, when viewing normal to film upper surface, the CWFs presented a tunable structural colour with the photonic band-gaps varying from UV to visible and NIR regions, which derived from the increasing helical pitch (from 195 nm, 365 nm, 475 nm to 1.38 µm for CWF1 to CWF4), typical of cholesteric organization (Figure 2B and 2C).…”

When nanocellulose meets diffraction grating: freestanding photonic paper with programmable optical coupling

“…It is well known that CNCs can selfassemble into a chiral nematic liquid crystal phase with its ordering preserved in a solid film after evaporation, producing vivid structural colour as observed in plants and certain animals when its helical pitch is on the order of the visible light wavelength. [19][20][21] Up to now, copious studies on CNC liquid crystals have been presented from the perspective of their templating, 22,23 colloidal assembly, [24][25][26][27] drying dynamics [28][29][30] and optical coupling with guest nanoparticles, [31][32][33][34] however, their potential uses as building blocks to fabricate periodic grating-like surface patterned films which have programmable photonic-photonic couplings still remain relatively unexplored, i.e., two spatial structures with different scales (micro and nano) coexist and modulate the light independently, showing hierarchical photonic structures.…”