Understanding Photomechanical Behavior of Liquid Crystalline‐Based Actuators

Abstract

Liquid crystalline‐based actuators containing azobenzene photoswitches have been used to demonstrate light‐responsive motion in soft actuator systems. Understanding the mechanical performance of these light‐responsive actuators as a function of the polymer chemistry as well as the nature and concentration of the photoswitches is crucial for developing advanced applications. A systematic study is presented here that clarifies the role of azobenzene photoswitches and the liquid crystalline networks in generating the desired photomechanical performance. Through measurement of photo stimulated mechanical behavior, in particular generated force and strain, a generalized set of guidelines concerning the appropriate subset of polymer chemistry and photoswitches required to achieve the desired performance for actuator design is derived.

Uniaxial photomechanical motion in large diameter polydimethylsiloxane optical fibers with fluoropolymer claddings

“…The effect can be reversible 14 – 16 or irreversible 17 – 19 Some well-studied mechanisms responsible for the photomechanical effect in solids include microscopic mechanisms such as photoisomerization 20 – 26 and photoreorientation 27 – 30 as well as macroscopic mechanisms such as electrostriction 31 – 33 and photothermal heating 34 – 39 Many materials can have multiple photomechanical response mechanisms 15 , 40 .…”

“…photoisomerization [20][21][22][23][24][25][26] and photoreorientation [27][28][29][30] as well as macroscopic mechanisms such as electrostriction [31][32][33] and photothermal heating. [34][35][36][37][38][39] Many materials can have multiple photomechanical response mechanisms.…”

Photomechanical bimorph fibers

“…They have been developed in a wide variety of forms, utilizing different structures and chemical changes to convert light into mechanical motion. Photomechanical technologies include photoactive-doped polymers, photochromic molecular crystals [1,2], and liquid crystalline-based devices [3]. There is an increasing interest in these technologies because they would require few components and could be powered solely by an appropriate light source.…”