Self-Elongating Liquid Crystal Elastomer Fibers for Active Textiles—Beyond Thermotropic Contraction

Liquid crystal elastomers (LCEs) integrate the anisotropic properties of rod-like mesogens into a loosely cross-linked polymer network. When molecularly aligned, LCEs can undergo a large and reversible actuation upon heating, making them promising for applications such as artificial muscles and soft robots. Among various LCE geometries, 1D LCE fibers or filaments has received considerable attention due to their scalable production, rapid actuation, and flexibility in shaping through diverse fabric manufacturing processes. While recent studies have successfully demonstrated thermoresponsive active textiles based on LCE fibers, all these examples exhibit thermotropic contraction. In this study, we report unprecedented "self-elongation (30% in strain)" of LCE fibers upon heating, which was fabricated through the extrusion-based spinning combined with UV curing. The extraordinary thermal behavior originates from the unique microstructure of our LCE fibers evidenced by x-ray scattering and microscopy. As a proof of concept, we demonstrate active textiles that can increase the pore size (~50%) upon heating, offering potential applications in thermoregulation.