A core/shell structured alginate hydrogel fibers with carboxymethyl cellulose coating for pH responsive color sensor

The low breaking strength and elongation rate of alginate fibers, coupled with the unsatisfactory encapsulation rate of the contents, constitute the primary factors limiting their application in the field of smart textiles. Therefore, a core-shell based composite hydrogel fiber of alginate @ carboxymethyl cellulose (ALG@CMC) and blueberry anthocyanin (BA) was studied, which can solve this problem and be used as a pH-responsive color sensor. ALG@CMC composite gel fiber was prepared by wet spinning and in-situ gel principle. FTIR analysis confirmed that the interaction between blueberry anthocyanins and ALG@CMC did not involve chemical changes. The surface of ALG fiber coated with CMC gel shell was confirmed by SEM. The colorimetric properties of ALG@CMC gel fibers at different pH were characterized. The encapsulation rate of anthocyanin (BA) increased from 54.27% to 87.02% after CMC gel shell coating. Concurrently, there was a significant enhancement in both the tensile strength and thermal stability. This work provides a new strategy for creating green and renewable textile color sensors, which has potential application value in the field of smart textiles.