Doubly-crosslinked, emulsion-templated hydrogels through reversible metal coordination. (22nd September 2017)

• Record Type: Journal Article
• Authors: Zhang, Tao; Silverstein, Michael S.
• Is Part Of: Polymer. Volume 126(2017)
• Page Start: 386
• Page End: 394
• Publication Date: 2017-09-22
• Subjects: Hydrogel polyHIPEs -- Metal coordination -- Shape memory -- Reversible crosslinking -- Absorption; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.07.044
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Double crosslinking can be used to significantly improve the mechanical properties of gels. Here, doubly-crosslinked hydrogel polyHIPEs (DC-PHs), which exhibited rapid water absorption, enhanced mechanical properties, and shape memory behaviour, were generated by forming metal coordination crosslinks within covalently crosslinked hydrogel polyHIPEs (HG-PHs), hydrogels formed by templating within oil-in-water high internal phase emulsions (HIPEs). The HG-PHs were based on acrylamide (AAm) and sodium acrylate (NaA), which provided − COO − groups, and were covalently crosslinked with N, N' -methylenebisacrylamide. The metal coordination crosslinking between the − COO − groups and Fe 3+ was generated by adding FeCl3 to the HG-PHs. The interconnected macroporous structures and the rapid water absorption of the HG-PHs were preserved in the DC-PHs, while the mechanical properties, in both the swollen and dry states, were significantly enhanced. The metal coordination crosslinking was easily removed through the light-induced reduction of the Fe 3+ in the presence of citric acid. The reversibility of the metal coordination crosslinking endowed the DC-PHs with a multiple-cycle shape memory behaviour. Graphical abstract: Highlights: Doubly-crosslinked hydrogel polyHIPEs (DC-PHs) were formed via metal coordination. DC-PHs possess interconnected macroporous structures with rapid water absorption. DC-PHs exhibit enhanced mechanical properties in both the swollen and dry states. DC-PH multiple-cycle shape memory is enabled via double crosslinking reversibility.