Nanocomposite hydrogels composed of cloisite 30B-graft-poly(acrylic acid)/poly(acrylic acid): Synthesis and characterization

Abstract

The hydrophilicity of Cloisite 30B is enhanced by surface grafting of polyacrylic acid (PAA). The radical polymerization of acrylic acid with the vinylsilylated Cloisite 30B leads to chemical grafting of PAA onto the organoclay surface. Chemical grafting of the PAA onto the surface of Cloisite 30B is shown by FTIR spectroscopy. Hydrogel nanocomposites are successfully prepared by using acrylic acid, vinylsilylated Cloisite 30B, and N,Nmethylene bisacrylamide as a crosslinker. Thermogravimetric analysis (TGA) and differential thermal mechanical analysis (DMTA) revealed that prepared hydrogel nanocomposites show enhanced ther� mal and mechanical properties than those of pure hydrogel (hydrogel without nanoparticles). Swelling degree and equilibrium swelling capacity of hydrogel nanocomposites 1-7 wt % (loaded with 1-7 wt % of vinylsily� lated Cloisite 30B, with respect to monomer) are also increased regarding to pure hydrogel. The interlayer and surface changes of the clay in the prepared nanocomposite materials and the grafted nanoparticles are studied by Xray diffraction and scanning electron microscopy.