Polymer hydrogels have attracted significant attention in recent years due to their promising role in diverse fields such as food industry, agriculture, medicinal chemistry, and environmental science.[1] The remarkable properties such as self-healing, shape memory, and swelling, along with improved mechanical strength, environmental and thermal stability, polymer hydrogel-based soft and smart materials have become one of the core areas in materials chemistry. In the seminal work, White et al. reported a self-healing system based on hydrogels with unique self-healing property, just like the natural ability of living creatures to repair their tissues.[2] This property offers the ability to extend the lifetime of products, which is usually limited by mechanical failures.[3] However, self-healing ability decreases the mechanical strength of the hydrogels, which sharply limits their applications.[4] At present, it remains a great challenge to create self-healing hydrogels with excellent strength, toughness, and recoverability. To overcome these issues, scientists came up with the idea of “Double-Network Design” polymer hydrogels model. In this design, two interpenetrating networks- covalent and non-covalent crosslinking- offer a strong structural basis to improve the mechanical properties as well as reversible self-healing properties.[5]
We hypothesized that the interplay between rigid covalent crosslinking and flexible non-covalent crosslinking can be controlled by tuning the stoichiometry of the components in a composite hydrogel. Also, we envision that introduction of nanofillers can enhance both mechanical and self-healing properties of the polymer based hydrogels. As a part of the initial study, we have prepared a series of composite hydrogels based on poly (acrylic acid-acrylamide) and varied amount of graphine oxide (GOXAAM) (x: 0.15, 0.50, and 1.0 wt% GO).[6] The gel exhibited enhanced mechanical strength, and excellent self-healing property. Further, the hydrogel could selectively adsorb organic cationic dyes from contaminated water. More importantly, the hydrogel was utilized as a solvent-induced slow-release source for graphene quantum dots (GQDs).
The seminar will provide an overview of the design, synthesis and application of self-healing hydrogels. In addition, details of the initial studies of the composite hydrogels based on graphene oxide and poly (acrylic acid-acrylamide) will also be presented.
References
[1] Y. Huang, M. Zeng, Z. Feng, D. Yin, Q. Xu, L. Fan, RSC Adv., 2016, 6, 3561.
[2] S. R. White, N. R. Sottos, P. H. Geubelle, J. S. Moore, M. R. Kessler, S. R. Sriram, E. N. Brown, S. Viswanathan, Nature, 2001, 409, 794.
[3] Z. Wei, J. H. Yang, J. Zhou, F. Xu, P. H. Dussault, Y. Osadag, Y. M. Chen, Chem. Soc. Rev., 2014, 43, 8114.
[4] I. Hussain, S. M. Sayed, S. Liu, O. Oderinde, M. Kang, F. Yao, G. Fu, Eur. Polym. J., 2018, 105, 85.
[5] H. P. Cong, P. Wang, S. H. Yu, Chem. Mater., 2013, 25, 3357. [6] S. D. Sahoo, E. Prasad, Soft Matter, 2020, 16, 2075.