Issue 75, 2017, Issue in Progress

Restorable, high-strength poly(N-isopropylacrylamide) hydrogels constructed through chitosan-based dual macro-cross-linkers with rapid response to temperature jumps

Abstract

To address the poor mechanical performance of conventional thermo-responsive poly(N-isopropylacrylamide) (pNIPAM) hydrogels, methacryloyl covalently-modified chitosan (methacryloylchitosan, MACS) was conceived as the chemical macro-cross-linker and employed cooperatively with chitosan, as the physical macro-cross-linker, to construct dually macro-cross-linked pNIPAM hydrogels for the first time. The employed MACS was synthesized through acylation of chitosan using methacrylic acid activated by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxy-succinimide (NHS). The influence of the preparation conditions, including the solids content, the dosage and component of the cross-linkers as well as the amount of the initiator, on the mechanical performance and swelling/deswelling properties of the obtained hydrogels was investigated systematically. The prepared dual-cross-linked pNIPAM hydrogels exhibit high mechanical strength, manifested in the achieved compressive stress of 8.75 MPa at 98% strain and tensile strength of 0.105 MPa. The high recovery efficiency (beyond 95%) from cyclic tensile tests reveals the good recoverability of these hydrogels. Moreover, they exhibit excellent thermo-responsiveness, to be more specific, rapid deswelling rates, i.e., most can release 50% of the absorbed water in ∼10 minutes on the temperature jump across the phase transition temperature. In particular, the deswelling rate increases with the increase of either the cross-linkers or MACS. The prominent mechanical performance and rapid responsiveness of the novel pNIPAM hydrogels is highly conductive for their future applications.

Graphical abstract: Restorable, high-strength poly(N-isopropylacrylamide) hydrogels constructed through chitosan-based dual macro-cross-linkers with rapid response to temperature jumps

Supplementary files

Article information

Article type
Paper
Submitted
12 Sep 2017
Accepted
04 Oct 2017
First published
11 Oct 2017
This article is Open Access
Creative Commons BY license

RSC Adv., 2017,7, 47767-47774

Restorable, high-strength poly(N-isopropylacrylamide) hydrogels constructed through chitosan-based dual macro-cross-linkers with rapid response to temperature jumps

X. M. Ma, R. Li, J. Ren, X. C. Lv, X. H. Zhao, Q. Ji and Y. Z. Xia, RSC Adv., 2017, 7, 47767 DOI: 10.1039/C7RA10148A

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