Growth of Colloidal Nanoplate Liquid Crystals Using Temperature Gradients

Abstract

Controlling colloidal self-assemblies using external forces is essential to develop modern electrooptical and biomedical devices. Importantly, shape anisotropic colloids can provide optical properties such as birefringence. Here we demonstrate that external temperature gradients can be effective in controlling nematic liquid crystalline (LC) order in suspensions of plate-like colloids also known as nanoplates. Nanoplates, in an isotropic suspension, wherein their orientations are random, could be effectively moved using a temperature gradient environment causing a phase transition to LC nematic phase. Such controllably formed nematic phase featured large nematic monodomains and enabled topologically more stable structures that were evident from the absence of hedgehog-type defects which are typically found in nematics formed spontaneously via nucleation and growth mechanism in a sufficiently high concentration suspension of nanoplates. Due to their high surface area-to-volume ratio and excellent thermophoretic properties, nanoplates can prove to be ideal candidates for transport of biomolecules through temperature varying environments.

Opto-Thermophoretic Manipulation

“…One of the interesting aspects is the possible relevance of thermophoresis to the origin of life, where the replication and accumulation of nucleotides under the non-equilibrium thermal condition on the early earth led to molecular assembly and evolution. 13−15 In recent decades, thermophoresis has been extensively exploited as a facile and contact-free technique for manipulation of colloidal particles and biomolecules, 16,17 throughs in colloidal assembly, 18,19 microfluidics, 20,21 sensing, 22,23 and biology. 24−27 Thermophoretic manipulation is a two-step process, that is, the design and acquisition of the temperature gradient field and the directed migration under the temperature gradient.…”

“…This general phenomenon provides a potential strategy to manipulate target objects in fluidic environments. One of the interesting aspects is the possible relevance of thermophoresis to the origin of life, where the replication and accumulation of nucleotides under the non-equilibrium thermal condition on the early earth led to molecular assembly and evolution. − In recent decades, thermophoresis has been extensively exploited as a facile and contact-free technique for manipulation of colloidal particles and biomolecules, , which contributes to tremendous breakthroughs in colloidal assembly, , microfluidics, , sensing, , and biology. − …”

Colloidal Nanosurfactants for 3D Conformal Printing of 2D van der Waals Materials

“…Recently, 2D nanomaterials have garnered research interests owing to their promising electronic/optical properties. [ 6–9 ] For example, flexible thin‐film transistors printed with 2D nanomaterials inks including graphene (Gr), transition metal dichalcogenide (TMD), and hexagonal boron nitride (h‐BN) have been demonstrated. [ 10 ] In the past decade, organic solvents including ethanol, cyclohexanone, terpineol, and ethylene glycol have been extensively investigated for the printing of 2D nanomaterials; [ 4,5 ] however, limitations of organic solvents still exist due to their inherent toxicity, flammability, and poor biocompatibility.…”

Electric Field Induced Electrorotation of 2D Perovskite Microplates

“…It should be clarified that “2D” here not only refers to a nanosheet with thickness less than 10 nm, but also include other planar configurations, as long as the lateral size is much larger than the thickness. Aside from the abovementioned 2D micromotors controlled by light stimuli, a diversity of other manners has been applied to power 2D micromotors, such as fuel-driven and magnetically driven techniques [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. Nevertheless, the experimental work relating to 2D micromotors still lags its 1D-nanowire counterpart mainly because of two aspects, i.e., suitable 2D material and optimal precisely controlled technique.…”