Preparation of high strength and transparent nanocomposite hydrogels using alumina nanoparticles as cross-linking agents

High strength and transparent nanocomposite hydrogels (AD gels) were prepared by photo-initiated free radical copolymerization of acrylic acid (AA) and N, N-dimethylacrylamide (DMAA) in the colloidal solutions of alumina nanoparticles (Al2O3 NPs). The obtained hydrogels displayed well-defined porous structures and outstanding mechanical properties with tensile and compressive strength up to 1.88 MPa and 28 MPa, respectively. The FT-IR spectra indicate that there exist strong chelation reactions between Al2O3 NPs and polymer matrix, which are responsible for the formation of AD gels and their excellent mechanical performance. Moreover, AD gels with low swelling ratios could be prepared by choosing appropriate monomer ratios, endowing the hydrogels with considerable mechanical strength even at swollen state. (C) 2018 Elsevier B.V. All rights reserved.