Photo-Responsive Shape-Memory and Shape-Changing Liquid-Crystal Polymer Networks

Abstract

“Surrounding matters” is a phrase that has become more significant in recent times when discussing polymeric materials. Although regular polymers do respond to external stimuli like softening of material at higher temperatures, that response is gradual and linear in nature. Smart polymers (SPs) or stimuli-responsive polymers (SRPs) behave differently to those external stimuli, as their behavior is more rapid and nonlinear in nature and even a small magnitude of external stimulus can cause noticeable changes in their shape, size, color or conductivity. Of these SRPs, two types of SPs with the ability to actively change can be differentiated: shape-memory polymers and shape-changing polymers. The uniqueness of these materials lies not only in the fast macroscopic changes occurring in their structure but also in that some of these shape changes are reversible. This paper presents a brief review of current progress in the area of light activated shape-memory polymers and shape-changing polymers and their possible field of applications.

Shape memory polybenzoxazines based on a siloxane-containing diphenol

“…Shape memory polymers (SMPs) are stimuli‐responsive materials with the ability to recover their permanent shapes in a predefined way from a temporary shape upon the application of an external stimulus, such as temperature, light, electric field, magnetic field, pH, and moisture . The capability of an SMP to recover its permanent shape from a temporary deformed shape in response to changes in temperature is called a thermally induced shape memory effect (SME) .…”

“…The basic structural requirements for a polymer designed to achieve an SME involves two aspects: netpoints and switch units . The netpoints serve as the fixity phase to memorize the permanent shape, and the switch units act as the reversible phase to fix the temporary shape . SME has been reported in different types of polymers, such as thermosets, thermoplastics, elastomers, hydrogels, and liquid crystals .…”

Synthetic Methodologies for Chelating Polymer Ligands: Recent Advances and Future Development

“…These polymers consist of cholesteric liquid crystal networks that reflect light and entangled polyacrylate networks that provide a humidity reaction, pH humidity and pH response. It should be noted the preparation of LCP networks of other types . For example, a polyacrylamide‐based cross‐linked film with fiber morphology is photomechanically sensitive .…”

Designs of Plasmonic Metamasks for Photopatterning Molecular Orientations in Liquid Crystals

“…Recent efforts in aligning LC molecules into spatially non-uniform orientation patterns have led to many new liquid crystal devices and applications, such as beam steering [1,2], q-plates [3][4][5][6], geometric phase wave plates [7,8], programmable origamis [9][10][11][12], controlled placement and assembly of particles [13][14][15][16], predesigned microfluidic electrokinetic flows in LCs [17,18], and command of active matter [19]. One technique is based on photoalignments through pixel-by-pixel direct laser writing [11,20].…”