Vacuum Thermoforming of Optically Switchable Liquid Crystalline Elastomer Spherical Actuators.

Liquid crystal elastomer (LCE) actuators are generally limited in shape, size, and quantity by the need for aligning via stretching and fixing via photopolymerizing. A thermoplastic LCE is presented that may be vacuum thermoformed into centimeter-sized hemispheres. The scalable industrial process induces LCE alignment without requiring postfixing.

Photo-activated dynamic isomerization induced large density changes in liquid crystal polymers: A molecular dynamics study.

We use molecular dynamics simulations to unravel the physics underpinning the light-induced density changes caused by the dynamic trans-cis-trans isomerization cycles of azo-mesogens embedded in a liquid crystal polymer network, an intriguing experimental observation reported in the literature. We employ two approaches, cyclic and probabilistic switching of isomers, to simulate dynamic isomerization. The cyclic switching of isomers confirms that dynamic isomerization can lead to density changes at specific switch-time intervals.

Geometry Controlled Oscillations in Liquid Crystal Polymer Films Triggered by Thermal Feedback.

Light-induced oscillatory behavior of liquid crystal polymer network (LCN) films has been demonstrated by several researchers in the past decade. Similarly, oscillations in LCN films under constant thermal stimulus have been reported recently, although the mechanism and the factors that govern the oscillatory behavior are not well understood. In this work, we study the dynamics of self-sustained oscillations exhibited by LCN films under a constant thermal stimulus through experiments and simulations.

An embedded interface regulates the underwater actuation of solvent-responsive soft grippers.

In this work, we report the role of an embedded interface between two polymer thin films in determining the overall folding and actuation characteristics of a bilayer system applied for gripping submerged objects. Along with the material properties and geometry of the individual films involved, the strength of the embedded interface governs the folding behaviour of the bilayer when exposed to a solvent. The concentration gradient developed across the film thickness when exposed to the solvent results in the deformation of the film.

Numerical analysis and design of a light-driven liquid crystal polymer-based motorless miniature cart.

Liquid crystal polymers are a special class of soft materials that can change their shape in response to numerous stimuli such as light, heat, electric field, and chemicals. The ability to tailor the deformed shape by tuning the alignment of mesogens across the film has enabled the researchers to generate unique motions from these liquid crystal polymer thin films. Simulating such motions might allow us to understand the underlying mechanisms better and could lead to novel designs.

Controlled shape morphing of solvent free thermoresponsive soft actuators.

High performance thermoresponsive soft, controllable and reversible actuators are highly desirable for diverse applications. The practical implementation of the existing poly(N-isopropylacrylamide) (pNipam) based soft thermoresponsive actuators faces serious limitations due to their functional requirement of proximal bulk solvent medium. In this work, addressing this issue, we report the development of a bilayer based actuator composed of a solvent responsive biodegradable polymer and temperature responsive pNipam.