Macromolecules, Vol.49, No.8, 3174-3183, 2016
Low Chemically Cross-Linked PAM/C-Dot Hydrogel with Robustness and Superstretchability in Both As-Prepared and Swelling Equilibrium States
Superior mechanical, recoverable, and swelling properties are important for the application practice of hydrogel. However, most of the hydrogels do not possess those three features at the same time. Herein, we have prepared a novel low chemical cross-linked polyacrylamide (PAM)/carbon nanodot (C-dot) hydrogel by introducing the C-dot into low chemically cross-linked PAM network. C-dot acts as both a physical cross-linker and lubricant in the low chemical cross-linked PAM network, and the synergistic effect between C-dot and PAM chains endows the hydrogel with extraordinary mechanical, recoverable, and swelling properties. The as-prepared hydrogel can be stretched over 3700% with fracture strength as high as 166 kPa, and it can keep high recoverability even when it is stretched up to 500% (more than 97% recovery ratio). Furthermore, the highest swelling ratio of the hydrogel is up to 235 times, which is much higher than that of the conventional PAM hydrogel. Moreover, even in the swelling equilibrium state, the hydrogel can be stretched up to 650% and almost completely recover once the stress is removed. The hydrogel with such an excellent mechanical property in both as-prepared and swollen states is barely reported and can greatly extend its potential application in biomedical fields.