Improvement of Mechanical Strength, Thermal Stability, Swelling, Moisture Content of Triple Network Hydrogels by Carbon Nanotubes

Abstract

In this study, we prepared a novel carbon nanotubes reinforced three network hydrogels composed of carbon nanotubes, polyacrylic acid(PAA), agar and polyvinyl alcohol(PVA), consisting of an agar gel as the first physical network, a PAA-Fe3+ gel as the second physical network and a polyvinyl alcohol as the third physical network. The surface modification of MWCNTs was carried out by oxyfluorination to introduce the functional groups on the hydrophobic MWCNTs. Agar/PAA-Fe3+/PVA/MWCNTs hydrogels with high tensile and compression strength(σf of 1.5 Mpa, Ɛf of 14.24 mm/mm) and (σf of 1.69 Mpa, the deformation of 80%), thermal stability, low-swelling, high moisture content properties were successfully prepared by a simple three-step method. The addition of carbon nanotubes has significantly improved the thermal stability of the gels, its thermogravimetric curve drops obviously until 387°C. Under the joint action of hydrogen bonding and ion coordination interaction, the gel achieves a perfect balance of swelling and moisture content. The research provide a new method to improve mechanical, swelling, thermal stability, moisture content ability by adjusting the compositions and interactions in the gels.