Preparation of bacterial cellulose-based Janus fibers with photothermal deformation

Flexible intelligent response devices are fabricated using several matrix materials. Among these, bacterial cellulose (BC) exhibits higher crystalline characteristics along with a higher degree of polymerization, elastic modulus, tensile strength, and water absorption. In this study, to further increase the response of fiber-based materials and expand their wearable applications, BC-based Janus fibers are prepared via wet spinning and used as fibrous intelligent response materials driven under photothermal stimulation. The BC-based Janus fibers exhibited excellent photothermal response with hydrophilic graphene oxide (GO)/BC as the actuation layer and hydrophobic graphene/BC as the supporting layer. When an infrared light was used to stimulate the GO side, the resulting dehydration and contraction of the GO side drove deformation. When the infrared stimulus was removed, the BC and GO quickly absorbed water and expanded owing to their favorable water-absorption properties. The material recovered its original straight shape, achieving reversible deformation. The experiment showed that the fibers prepared with 35 wt% GO and 100 wt% graphene exhibited a superior photothermal actuation performance compared to the BC fibers, GO/BC fibers, and graphene/BC fibers. When the actuation layer was exposed to infrared light for 27 s, the fibers started to bend upward along the illuminated section. After 55 s of exposure, the bending angle reached 135°. After the infrared light was turned off, the bent fibers returned to their original straight shape.