Characteristics of self-healable laponite-poly(N-isopropylacrylamide) hydrogels prepared by gamma-ray irradiation

Abstract

There have been many strategies and efforts to develop nanocomposite gels for wide applications that display desirable strength and properties, such as self-healing. In this study, self-healable laponite-poly(N-isopropylacrylamide) hydrogels were prepared by gamma-ray radiation employing stepwise processes that provide gelation without any chemicals for crosslinking and initiation. This method achieved self-healable properties similar to that of typical gels crosslinked using crosslinkers and initiators. We found that the main factor of the property is the homogeneous distribution of laponite particles, based on comparisons of samples prepared using various synthetic strategies. Regarding the relationship between synthetic methods and their respective properties, the samples were characterized via swelling ratios, rheological properties, cross-sectional images, and nanostructures. The uniformity of the networks was evaluated with mesoscopic structures associated with large inhomogeneities and nanostructures described with interparticle distances at different swelling ratios. The results indicate that the stepwise process of the radiation method generates dense networks with uniform structures, which leads to self-healing ability. Consequently, we suggest that gelation by gamma-ray irradiation can provide better properties via effective chemical controls.