Nanocomposite Hydrogels with High Mechanical Strength and High Swelling Ratio by RAFT Polymerization

Abstract

Nanocomposite hydrogels (NC gels) have been prepared based on poly(N-isopropylacrylamide) (PNIPAM) containing 0.25-15 wt% of the expandable synthetic hectorite Laponite XLS (Clay-S) by reversible addition fragmentation chain transfer (RAFT) polymerization. The swelling behaviors were investigated and the hydrogels by RAFT polymerization (RAFT gels) showed accelerated shrinking kinetics and higher swelling ratio comparing with conventional hydrogels (CGel). This could be attributed to the presence of dangling chains mainly caused by chain transfer reagent (CTA), which could retard the crosslinking reaction rate greatly. Furthermore, the NC gels have stronger mechanical strength than CGel. The presence of Clay-S does not affect the value of the lower critical solution temperature (LCST).

Keywords:

• Clay
• high mechanical strength
• nanocomposite hydrogels
• RAFT

Acknowledgements

This work was supported by “the Fundamental Research Funds for the Central Universities” (grant 2011-IV-091), supported by the national natural science foundation of china under grant no. 51103112, and supported by the Major State Basic Research Program of China under grant no. 2011CB606205.