Versatile homeotropic liquid crystal alignment with tunable functionality prepared by one-step method

Zhang, Yang; Yang, Weiping; Gu, Minzhao; Wei, Qunmei; Lv, Pengrong; Li, Ming; Liu, Danqing; Zhao, Wei; Broer, Dirk J.; Zhou, Guofu

doi:10.1016/j.jcis.2021.10.159

Cited by 15 publications

(6 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Strict conditions, such as confinement [9,11], electromagnetic fields [12][13][14][15], and surface anchoring [16], have been exploited to manipulate the director field of liquid crystals and retard the relaxation. Currently, the achieved MDLCs of small molecules are only several micrometers thick due to the attenuation of surface anchoring energy or weak confinement effect [17,18]. MDLCs prepared by electromagnetic fields require continuous external field energy, otherwise they exhibit extremely fast relaxation due to weak mesogen interactions [13].…”

Section: Introductionmentioning

confidence: 99%

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

et al. 2022

View full text Add to dashboard Cite

Eliminating topological defects to achieve monodomain liquid crystals is highly significant for the fundamental studies of soft matter and building long-range ordered materials. However, liquid crystals are metastable and sensitive to external stimuli, such as flow, confinement, and electromagnetic fields, which cause their intrinsic polycrystallinity and topological defects. Here, we achieve the monodomain liquid crystals of graphene oxide over 30 cm through boundary-free sheargraphy. The obtained monodomain liquid crystals exhibit large-area uniform alignment of sheets, which has the same optical polarized angle and intensity. The monodomain liquid crystals provide bidirectionally ordered skeletons, which can be applied as lightweight thermal management materials with bidirectionally high thermal and electrical conductivity. Furthermore, we extend the controllable topology of two-dimensional colloids by introducing singularities and disclinations in monodomain liquid crystals. Topological structures with defect strength from − 2 to + 2 were realized. This work provides a facile methodology to study the structural order of soft matter at a macroscopic level, facilitating the fabrication of metamaterials with tunable and highly anisotropic architectures.

show abstract

Section: Introductionmentioning

confidence: 99%

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

et al. 2022

View full text Add to dashboard Cite

show abstract

“…After cooling down to room temperature, the LC homeotropic alignment was verified with polarized optical microscopy (POM), showing a black and monochromatic image regardless of the orientation of the sample to the crossed polarizers. [ 19 ] Thereafter, the aligned LC cells were employed for 3D laser printing using a commercial two‐photon lithography setup (see Experimental Section).…”

Section: Resultsmentioning

confidence: 99%

A Facile Approach for 4D Microprinting of Multi‐Photoresponsive Actuators

Hsu

Mainik

Münchinger

et al. 2022

Adv Materials Technologies

View full text Add to dashboard Cite

For microscale 4D photoresponsive actuators, light is crucial in two ways. First, the underlying additive manufacturing techniques rely on photopolymerization processes triggered by the absorption of light. Second, the absorption of light serves as the actuation stimulus. The two absorptions can be conflicting. While the microstructure requires strong absorption at the actuation wavelength(s), this absorption should not interfere with that of the manufacturing process. Herein, a simple strategy is proposed to overcome these limitations and allow for the fabrication of multi‐photoresponsive 3D microstructures that can be actuated at different wavelengths of light. Two‐photon 3D laser printing is selected as the fabrication technique and liquid crystalline (LC) elastomers as the functional materials. In a first step, 3D microstructures are fabricated using an aligned LC ink formulation. Thereafter, up to five different dyes exhibiting absorptions that extend over the entire visible regime (400–700 nm) are successfully incorporated into the LC microstructures by an exchange process enabling a programmable actuation by irradiating with the suitable wavelength. Furthermore, by combining dyes exhibiting orthogonal absorptions, wavelength‐selective actuations are demonstrated.

show abstract

“…Continuous polymer networks that connect the top and bottom substrates can be clearly observed in the cross-sectional view for samples A3 and B, which is a characteristic feature of PSLCs. 39 However, RAFT polymerization leads to a rather ordered network structure with polymer bundles aligned perpendicularly to the substrates in sample A3, while traditional FR polymerization produces a more chaotic and poorly ordered structure in sample B. Such differences can be explained by the different polymerization reaction kinetics (vide infra).…”

Section: Comparison Of Pslc Devices Prepared Via Fr and Raft Polymeri...mentioning

confidence: 99%

Unique Polymer-Stabilized Liquid Crystal Structure Prepared by Addition of a Reversible Addition–Fragmentation Chain Transfer Agent

Zhang,

Zhan,

Wang

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Polymer-stabilized liquid crystals (PSLCs) are important electrically switchable materials due to their superior electro-optical properties. Nevertheless, it remains a formidable challenge to balance PSLCs' instant electro-optical performance and long-term durability due to their relatively low polymer content and the related sensitivity to external force. Herein, we demonstrate the possibility of regulating the polymer network structure in PSLCs via reversible addition− fragmentation chain transfer (RAFT) polymerization reactions of acrylate monomers with a chain transfer agent (CTA). By controlling the concentration of CTA and conditions of photopolymerization, the kinetics of the polymerization reaction can be modified. Compared to conventional free-radical (FR) polymerization, the reduced chain growth rate leads to sufficient chain relaxation, reorientation of liquid crystal (LC) directors, and alleviation of shrinkage stresses in the RAFT polymerization process. This in turn produces an ordered polymer network structure in the vertical direction and a uniform distribution in the horizontal plane. As a result, the PSLC network presents increased elasticity with a lower hysteresis effect and greatly improved durability. Our research offers insightful guidance for the finetuning of polymer network structures to prepare advanced LC/polymer composite structures with outstanding performances.

show abstract

Versatile homeotropic liquid crystal alignment with tunable functionality prepared by one-step method

Cited by 15 publications

References 42 publications

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

A Facile Approach for 4D Microprinting of Multi‐Photoresponsive Actuators

Unique Polymer-Stabilized Liquid Crystal Structure Prepared by Addition of a Reversible Addition–Fragmentation Chain Transfer Agent

Contact Info

Product

Resources

About