Polymer hydrogels are promising candidates in materials chemistry, not only for meeting the need based applications in daily life but also for addressing many challenges in advanced industry, due to their fascinating properties such as self-healing, stimuli-responsive nature, and shape memory effect. 1 While self-healing property makes polymer hydrogel a desirable candidate for biomedical applications, poor mechanical strength limits the scope of applications.
2 Developing self-healing hydrogels with excellent strength, toughness, and recoverability remains a challenge in this field. In order to address this challenge, a “Double Network” (DN) design strategy has been utilized to develop hydrogels, where two types of interpenetrating networks offer a strong structural basis to improve mechanical and reversible self-healing properties.3 In the present work, a DN
hydrogel based on graphene oxide and poly (acrylic acid-acrylamide) [GOxAAM] is synthesized, which exhibits enhanced self-healing ability with reasonable mechanical strength. The hydrogel has been used for
selective adsorption of organic dyes under neutral conditions, and the adsorption kinetics follow pseudo-second-order and intraparticle diffusion models. 4 Next work demonstrates a conductive, self-healable,
and self-adhesive DN hydrogel consisting of chitosan, tetraethylene glycol, and polyacrylic acid using three different types of crosslinkers. The obtained DN hydrogels exhibit excellent tunable mechanical properties where fracture stress ranges from 180 to 1170 kPa and fracture strain ranges from 870 to 1175 %. The third project involves the design and synthesis of water-induced shape memory DN composite hydrogels based on polyvinyl alcohol-co-polystyrene (PVA-PSX) to prepare a composite film of optimum transparency, improved
water resistance, enhanced shape memory behaviour, reduced UV-light transmission, and effective antimicrobial activity, which can be used as packaging materials in food and cosmetic industry. The fourth project introduces a novel elastic polyacrylic acid/ tricarballylic acid DN hydrogel using Fe3+ as an ionic crosslinker. Dual crosslinking effects stabilize the 3-dimensional network structure in the hydrogels through
dynamic ionic interactions, and initial results suggest that the material can be used as 2D/3D printable ink-gel.
Reference
1. Y. Huang, M. Zeng, Z. Feng, D. Yin, Q. Xu, L. Fan, RSC Adv., 2016, 6, 3561.
2. Z. Wei, J. H. Yang, J. Zhou, F. Xu, P. H. Dussault, Y. Osadag, Y. M. Chen, Chem. Soc. Rev., 2014, 43,
8114.
3. H. P. Cong, P. Wang, S. H. Yu, Chem. Mater., 2013, 25, 3357.
4. S. D. Sahoo, E. Prasad, Soft Matter, 2020, 16, 2075.