Comparative Study of Graphene Oxide-Gelatin Aerogel Synthesis: Chemical Characterization, Morphologies and Functional Properties

Graphene oxide (GO)-gelatin (G) aerogels were synthesized by covalent and noncovalent methods, changing on the synthesis the GO:G ratio and the pH of the GO suspension, evaluating the physical, chemical, and functional properties of these materials. Comparatively, low GO:G ratios with alkali GO suspension promoted GO-G interactions for covalent aerogels. In contrast, high GO:G ratios under acidic conditions promoted noncovalent interactions. Scanning electron microscopy showed heterogeneous structures with pore sizes of 53.26 +/- 25.53 mu m and 25.31 +/- 10.38 mu m for covalent and noncovalent aerogels, respectively. The synthesis method did not influence the surface charge; however, differences were depending on the GO content and their chemical activation, shifting from 15.63 +/- 0.55 mV to - 20.53 +/- 1.07 mV. Noncovalent aerogels presented higher absorption ratios in phosphate-buffered saline (PBS) solution (35.5 +/- 2.4 g(PBS)/g(aerogel)-49.6 +/- 3.8 g(PBS)/g(aerogel)) than covalent aerogels. Therefore, due to these properties, noncovalent aerogels could be more useful than covalent aerogels for absorption potential applications, as biomedicine or water-treatment, where the promotion of surface interactions and high absorption capability is desired.