Dynamic Shape Change of Liquid Crystal Polymer Based on An Order‐Order Phase Transition

Abstract

Liquid crystal actuators conventionally undergo shape changes across an order‐disorder phase transition between liquid crystal (LC) and isotropic phases. In this study, we introduce an innovative Liquid Crystal Polymer (LCP) actuator harnessing an order‐order LC phase transition mechanism. The LCP film is easily stretchable within the LC phase, facilitated by the π‐π stacking of phenyl groups serving as robust physical crosslinking points, and thereby transforms to a stable monodomain structure. The resultant monodomain LCP actuator shows a distinctive reversible dynamic shape change, exhibiting extension followed by contraction along the LC director on cooling. The extension is propelled by the reversible smectic C to smectic A phase transition, and the contraction is attributed to the re‐entry to the smectic C phase from smectic A phase. Thermal annealing temperature determines this peculiar dynamic shape change, which occurs during both heating and cooling processes. This pivotal attribute finds manifestation in gripper and flower‐shaped actuators, adeptly executing grabbing and releasing as well as blooming and closure motions within a single thermal stimulation. In essence, our study introduces an innovative approach to the realm of LCP actuators, ushering in a new avenue for the design and fabrication of versatile and dynamically responsive LCP actuators.

4D Printing of Shape-Morphing Liquid Crystal Elastomers

“…The molecules are organized in a layered structure parallel to each other, and the long axes of the molecules in the layer are parallel to each other, arranged neatly, and perpendicular to the layer (smectic A phase) or form a certain angle (smectic C phase). Under certain conditions, the smectic A and smectic C phases can undergo a reversible phase transition . While these molecules maintain lateral mobility within the layer and exhibit fluidity, their viscosity remains significantly high.…”

“…Under certain conditions, the smectic A and smectic C phases can undergo a reversible phase transition. 27 While these molecules maintain lateral mobility within the layer and exhibit fluidity, their viscosity remains significantly high. Nonetheless, these molecules are unable to traverse between the layers, leading to a high degree of order, which is typically observed at lower temperatures.…”

Ligand Dissociation of Metal-Complex Photocatalysts toward pH-Photomanipulation in Dynamic Covalent Hydrogels for Printing Reprocessable and Recyclable Devices

“…Dynamic polymers have garnered significant attention due to their unique dynamic features and similar mechanical performances to traditional static polymers. − Their reversible networks allow them to reconfigure and restructure, with potential applications in high-performance smart materials, soft devices, electronics, and other fields. − For example, programmatically controlling the dynamic equilibrium in polymers enables precise shape-memory behavior in specific environments. − Their dynamic nature gives them excellent self-healing, reprocessable, and recyclable properties under external stimuli. − Especially dynamic hydrogels, with their water-rich and porous structures, offer biomimetic microenvironments, while reversible bonding provides mechanical dynamics for stiffness control in cell culture, tissue repair, and conformable bioelectronics fabrication. − Moreover, dynamic polymer hydrogels with covalent bonding interactions demonstrate superior mechanical performance to those with noncovalent interactions. Combining hydrogel preparation with emerging additive manufacturing technologies can further extend their advanced applications with complex structures. , Therefore, developing high-performance dynamic covalent hydrogels is essential and presents an intriguing topic in related fields.…”