Preparation and Characterization of Stimuli-Responsive Poly(N-Isopropylacrylamide)/Ca-Alginate Hydrogel Fiber by Microfluidic Spinning

Smart hydrogel is a kind of new soft and wet material which can be responsive to external stimuli. Hydrogel fiber owning one dimension size can significantly improve response speed and be easily formed into higher-order assemblies. N-isopropylacrylamide/calcium alginate (NIPA/Ca-alginate) as-spun fiber was generated via microfluidic spinning. Then PNIPA/Ca-alginate hydrogel fiber was prepared through off-chip free radical polymerization of NIPA in the presence of Ca-alginate. The structure and morphology of the hydrogel fiber were characterized by FTIR and SEM. The swelling property and temperature-/pH-response behaviors were also investigated. The PNIPA/Ca-alginate hydrogel fiber had a 3D network porous structure. The thinner the hydrogel fiber, the faster the swelling speed was. Meanwhile, the hydrogel fiber exhibited temperature and pH response.