Designing Hydrogels with Energy Dissipation and Rapid Elastic Recovery Through Network Architecture
Literature seminar abstract
Recently, hydrogels have shown promise in a wide variety of materials applications from membranes to soft tissue replacement. The polymer network structure provides an avenue to tune mechanical properties such as elasticity and modulus. However, the swollen polymer chains do not dissipate energy well making hydrogels very brittle; a single crack can cause catastrophic failure of the material. In 2003, Gong and coworkers developed a double network hydrogel to dissipate energy through breaking of covalent bonds in a highly cross-linked first network.1 This design increased the toughness of the gel, but the modulus could not be recovered.2 Since then, there has been a push to design tough hydrogels which can recover quickly and elasticly.3 Two recent high profile studies will be discussed in this seminar to explore hydrophobic association and ionic bonds networks as energy dissipation and recovery mechanisms. Chen and coworkers designed a hydrogel with two physically cross-linked networks.4 The agar and hydrophobically associated polyacrylamide hydrogel was soft, highly stretchable, and dissipated energy, but only recovered 60% of its modulus after 120 minutes. Alternately, Gong used cationic and anionic monomers to form weak and strong crosslinks within the polymer network.5 The weak crosslinks “unzip” by breaking the ionic bonds to dissipate energy and then return to 100% of the hydrogel modulus after 120 minutes. The comparison of these mechanisms will be used to determine a strategy for incorporating energy dissipation into current hydrogel networks without sacrificing the material’s elastic properties.
(1) Gong, J. P.; Katsuyama, Y.; Kurokawa, T.; Osada, Y. Adv. Mater. 2003, 15 (14), 1155–1158.
(2) Webber, R. E.; Creton, C.; Brown, H. R.; Gong, J. P. Macromolecules 2007, 40 (8), 2919–2927.
(3) Zhao, X. Soft Matter 2014, 10, 672-687.
(4) Chen, Q.; Zhu, L.; Chen, H.; Yan, H.; Huang, L.; Yang, J.; Zheng, J. Adv. Funct. Mater. 2015, 25 (10), 1598–1607.
(5) Luo, F.; Sun, T. L.; Nakajima, T.; Kurokawa, T.; Zhao, Y.; Sato, K.; Ihsan, A. Bin; Li, X.; Guo, H.; Gong, J. P. Adv. Mater. 2015, 27 (17), 2722–2727.
Speaker: Allee Klug
Speaker Institution: Colorado State University
Event Date: 11-10-2017
Event Time: 4:00 PM
Event Location: Chemistry A101
Mixer Time: 3:45 PM
Mixer Location: Chemistry B101E
Host: T. Bailey