Porous Liquid‐Crystalline Networks with Hydrogel‐Like Actuation and Reconfigurable Function

Abstract

A porous liquid‐crystalline network (LCN), prepared by using a template method, was found to exhibit peculiar actuation functions. The creation of porosity makes the initially hydrophobic LCN behave like a hydrogel, capable of absorbing a large volume of water (up to ten times the sample size of LCN). When the amount of absorbed water is relatively small (about 100 % swelling ratio), the porous LCN displays anisotropic swelling in water and, in the same time, the retained uniaxial alignment of mesogens ensures a thermally induced shape change associated with a LC‐isotropic phase transition. Combining the characteristic actuation mechanisms of LCN (order–disorder transition of mesogens) and hydrogel (water absorption), such porous LCNs can be explored for versatile stimuli‐triggered shape transformations. Moreover, the porosity enables loading/removal/reloading of functional fillers such as ionic liquids, photothermal dyes and fluorophores, which imparts the porous LCN actuator with reconfigurable functions such as ionic conductivity, light‐driven locomotion, and emissive color.

Perspiring Soft Robotics Skin Constituted by Dynamic Polarity‐Switching Porous Liquid Crystal Membrane

“…To this end, we utilize liquid crystal polymer networks (LCNs) as the liquid reservoir. LCNs are a typical class of materials that have anisotropic characteristics which have been extensively employed in optical devices, [15][16][17] soft actuators, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] and dynamic surfaces. [5,[34][35][36][37][38][39][40][41] We take advantage of the reduction of molecular order, upon the actuation of the LCNs, [42,43] to eject the initially stored primary liquid to the coating surface.…”

Organic‒inorganic semi-interpenetrating networks with orthogonal light- and magnetic-responsiveness for smart photonic gels

“…Stimuli-responsive materials are smart materials that are responsive to external stimuli such as light 1 – 4 , electric 5 and magnetic fields 6 , 7 , temperature 8 , 9 , humidity 10 , 11 , or pH 12 – 15 . Stimuli-responsive materials are widely studied because they exhibit potential applications in robotics 16 , biomedicine 17 , 18 , self-healing 19 – 21 , photonics 22 , etc.…”

Semi‐Crystalline Rubber as a Light‐Responsive, Programmable, Resilient Robotic Material

“…The actuation mechanism in the majority of stimuli‐responsive polymers is rooted in reversible phase transitions, such as glass transition in shape memory polymers (SMPs), [ 10,11 ] nematic‐to‐isotropic transition in liquid crystal elastomers (LCEs), [ 12,13 ] and coil‐to‐globule transition in hydrogels. [ 14,15 ] Such phase transitions are typically triggered by heat and manifest themselves in reversible strain or shape changes.…”

“…[7][8][9] Accordingly, such polymers are important candidates for realizing wirelessly controlled soft actuators with much smaller sizes than their pneumatic and dielectric counterparts. [2,4] The actuation mechanism in the majority of stimuli-responsive polymers is rooted in reversible phase transitions, such as glass transition in shape memory polymers (SMPs), [10,11] nematic-to-isotropic transition in liquid crystal elastomers (LCEs), [12,13] and coil-to-globule transition in hydrogels. [14,15] Such phase transitions are typically triggered by heat and manifest themselves in reversible strain or shape changes.…”