title: A novel thermoresponsive hydrogel with ion-recognition property through supramolecular host-guest complexation.
abstract: A novel thermoresponsive hydrogel with ion-recognition property was prepared via free-radical cross-linking copolymerization of N-isopropylacrylamide (NIPAM) with benzo-18-crown-6-acrylamide (BCAm) as host receptor. Both chemical structures and stimuli-sensitive properties of the prepared poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) P(NIPAM-co-BCAm) hydrogel were characterized. The smart hydrogel could respond to both temperature and ion stimuli. When the crown ether units captured Ba2+ and formed stable BCAm/Ba2+ host-guest complexes, the lower critical solution temperature (LCST) of the hydrogel increased due to the repulsion among charged BCAm/Ba2+ complex groups and osmotic pressure within the hydrogel. Whereas crown ethers captured Cs+, the LCST shifted to a lower temperature because of the formation of 2:1 sandwich complexes. Unexpectedly, the LCST of the cross-linked P(NIPAM-co-BCAm) hydrogel in K+ solution did not shift to a higher temperature, which was definitely different from the previously reported linear P(NIPAM-co-BCAm) copolymer in K+ solution. The results of this work provide valuable information for development of dual thermo- and ion-responsive hydrogels which have potential applications in drug controlled-release systems or biomedical fields.
authors.affiliation: School of Chemical Engineering, Institute for Nanobiomedical Technology and Membrane Biology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Ju
authors.forename: Liang-Yin
authors.initials: LY
authors.lastname: Chu
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Peng
authors.initials: P
authors.lastname: Mi
authors.forename: Young Moo
authors.initials: YM
authors.lastname: Lee
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003432:Cross-Linking Reagents; D007477:Ions; D011108:Polymers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate