Light Propagation and Photoactuation in Densely Cross-Linked Azobenzene-Functionalized Liquid-Crystalline Polymers: Contribution of Host and Concerted Isomerism

Abstract

The photomechanical behavior of azobenzene-functionalized liquid-crystalline polymers (azo-LCPs) is closely related to UV light propagation. Here, we report the effect of light absorption by the LC host and the concerted isomerism of azobenzene on this property. In situ measurements of light absorptivity and computer simulations revealed that the light propagation of a liquid-crystalline polymer is affected by the UV absorption of the LC host under the same concerted isomerism of azobenzene. The lower UV light absorption of the LC host results in deeper UV light propagation and a sharper isomerization profile, which eventually induces faster bending when compared to the higher UV light absorption of the LC host. On the other hand, increasing the azobenzene concentration in the polymer greatly decreases the speed of light propagation, which is regarded as one of the factors inhibiting further increases in the bending speed of azo-LCP films.

Soft Tendril-Inspired Grippers: Shape Morphing of Programmable Polymer–Paper Bilayer Composites

“…To produce the general motions of plant tendrils using polymer-based structures, the fabricating and programming process of these structures in previous studies always includes a series of specific steps which always involve special devices and tedious manual operations. − Meanwhile, polymer-activated shape-morphing structures fabricated through three-dimensional (3D) printing named as four-dimensional (4D) printing have been investigated with the dominating advantages of being capable of synchronously fabricating and programming polymer structures. − Direct printing technology could be easily adapted for producing the fundamental modes of tendril deformation such as bending and twisting. ,, Meanwhile, polymer materials that are able to respond to a wide range of stimuli such as heat, water, light, − and magnetic field can be used for designing untethered polymer-activated shape-morphing mechanisms with contactless remote control. Additionally, these shape-morphing structures have the excellent shape-retaining capability that they could maintain their deformed shapes in the high stiffness when the stimulus was removed. , On the basis of the advantages of 3D printing and polymer-activated shape-morphing structures, this research aims to develop a more versatile and economical approach to fabricate tendril-like grasping mechanisms utilizing 3D printing as a single manufacturing step that requires only a 3D printer and inexpensive off-the-shelf materials.…”

Light-Induced Actuation of Poly(dimethylsiloxane) Filled with Graphene Oxide Grafted with Poly(2-(trimethylsilyloxy)ethyl Methacrylate)

“…Materials that show a light-induced capability usually consist of two phases, the filler, and the polymer matrix. The former includes mainly organic [16,17] and carbon-based fillers [18,19,20], while the latter can be formed by various systems. The most frequent matrix is poly(dimethylsiloxane) elastomer (PDMS) [20], but in some cases, the thermoplastic elastomers [13], polyurethanes [21], or rubber compounds [22] have been successfully applied.…”

An artificial aquatic polyp that wirelessly attracts, grasps, and releases objects

“…Higher light intensities lead to faster propagation of the cis – trans gradient. Higher azobenzene concentration (10 mol %) significantly slows down the propagation of the trans–cis boundary ( 37 ) so that only prolonged illumination times (>20 s) will lead to considerable decreases in the tip displacement ( Fig. 2 C ).…”