Micellar-incorporated hydrogels with highly tough, mechanoresponsive, and self-recovery properties for strain-induced color sensors. Issue 43 (5th October 2018)

• Record Type: Journal Article
• Authors: Zhang, Yanxian; Ren, Baiping; Yang, Fengyu; Cai, Yongqing; Chen, Hong; Wang, Ting; Feng, Zhangqi; Tang, Jianxin; Xu, Jianxiong; Zheng, Jie
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 43(2018)
• Page Start: 11536
• Page End: 11551
• Publication Date: 2018-10-05
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8tc03914c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A new strategy is developed to incorporate hydrophobic spiropyran mechanophores into the gel network for fabricating tough and mechanoresponsive hydrogels used for strain-induced color sensor. Abstract : Tough, mechanoresponsive hydrogels have broad and significant impacts on fundamental research and practical applications, but have proved to be extremely challenging to develop. The poor solubility of mechanophores makes them difficult to be integrated into a highly hydrophilic network of hydrogels. In this work, we synthesized dimethylacrylate-functionalized spiropyran (SP) mechanophores and used them as crosslinkers to copolymerize with hydrophobic methyl acrylate (MA) monomers and hydrophilic acrylamide (AM) monomers in the presence of surfactant polysorbate 80 (TWEEN 80) micelles, forming poly(AM- co -MA/SP) hydrogels. The mechanical properties of the as-prepared and swollen poly(AM- co -MA/SP) hydrogels strongly depend on network components (AM, MA, and SP concentrations). Thus, the optimal hydrogels can achieve excellent mechanical properties (tensile stress of 1.1 MPa, tensile strain of 6 mm mm −1, elastic modulus of 1.1 MPa, and tearing energy of 3200 J m −2 ). Due to multi-stimuli responses of SP crosslinkers, the hydrogels exhibited the reversible changes in color and mechanical properties between the force-, heat-, and UV light-induced deformation state and the white light-induced recovery state. Based on their fast, reversible, force-induced color change behavior, we further designed a conceptual hydrogel strain sensor to monitor color change under the stretching and relaxing processes in multiple cycles. This work demonstrates that the presence of dynamically reversible SP crosslinkers and micellar structures is the key to greatly enhance both mechanical and color recoverable properties of poly(AM- co -MA/SP) hydrogels, which could serve as promising smart materials for a variety of applications such as soft robots, electronic skins, and strain/motion/damage sensors.