title: Multistimuli-Responsive, Moldable Supramolecular Hydrogels Cross-Linked by Ultrafast Complexation of Metal Ions and Biopolymers.
abstract: A new type of multistimuli-responsive hydrogels cross-linked by metal ions and biopolymers is reported. By mixing the biopolymer chitosan (CS) with a variety of metal ions at the appropriate pH values, we obtained a series of transparent and stable hydrogels within a few seconds through supramolecular complexation. In particular, the CS-Ag hydrogel was chosen as the model and the gelation mechanism was revealed by various measurements. It was found that the facile association of Ag(+) ions with amino and hydroxy groups in CS chains promoted rapid gel-network formation. Interestingly, the CS-Ag hydrogel exhibits sharp phase transitions in response to multiple external stimuli, including pH value, chemical redox reactions, cations, anions, and neutral species. Furthermore, this soft matter showed a remarkable moldability to form shape-persistent, free-standing objects by a fast in situ gelation procedure.
authors.affiliation: Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen 518055 (China).
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen 518055 (China).
authors.forename: Fucong
authors.initials: F
authors.lastname: Lv
authors.affiliation: Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen 518055 (China).
authors.forename: Lujie
authors.initials: L
authors.lastname: Cao
authors.affiliation: College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000 (China).
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.affiliation: College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China). yzhangcsu@csu.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen 518055 (China). luzg@sustc.edu.cn.
authors.forename: Zhouguang
authors.initials: Z
authors.lastname: Lu
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D010084:Oxidation-Reduction; D044367:Phase Transition; D012834:Silver / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D020100:Hydrogels; D007477:Ions; D012834:Silver; D048271:Chitosan
keywords: biopolymers; hydrogels; sol-gel processes; supramolecular chemistry; transition metals