Strontium ion substituted alginate‐based hydrogel fibers and its coordination binding model

ABSTRACT Sr‐alginate and Ca‐alginate hydrogel fibers were fabricated via microfluidic spinning technology, and various analytical methods were adopted to characterize fibers and disclose the coordination model of Sr2+ binding with alginate molecule chain. For both fibers, the more crosslinking sites of Sr2+ with alginate molecule were illustrated in comparison with that of Ca2+. The more robust mechanical performance of Sr‐alginate fibers than Ca‐alginate counterpart was a strong indication of the more strong binding of Sr2+ with alginate molecular chain. FTIR and electric conductivity disclosed the chelation type of Sr2+ with alginate macromolecule being similar to that of Ca2+, which was core‐shell of the analogous “egg‐box” structure. Circular dichroism spectroscopy further certified the extra coordination sites for Sr2+ with alginate molecule than Ca2+. Research on the coordination model will be more beneficial to optimizing the physicochemical properties of alginate fibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48571.