Preparation and mechanical properties of silica nanoparticles reinforced composite hydrogels

Nanocomposite hydrogels consisting of inorganic (silica nanoparticles, SNPs)/organic (poly(acrylic acid), PAA) network structures are synthesized by in situ free polymerization from SNP surface in an acrylic acid (AA) aqueous solution. The effects of composition, including concentrations of SNP (C-SNP) and AA (C-AA), on hydrogels reinforcement behaviors are investigated, and the results reveal that the mechanical properties of the network are markedly influenced by C-SNP as well as C-AA. In contrast to chemical gels that cross-linked by N,N'-methylene-bisacrylamide (BIS), the SNP-PAA gels show excellent tensile properties, with elongation at break up to 900% and tensile strength greater than 300 kPa. All these results are consistent with the proposed cross-linked network structures for SNP-PAA gels. (C) 2014 Elsevier B.V. All rights reserved.