Improvement of hydrophobic and mechanical properties of magnetite aerogel

Aerogels are a class of materials that are composed of a three dimensional network of solid particles with gas-filled pores between them. Due to the porous nature of aerogels their density is extremely low, and they remain the lightest known solids. Magnetite, Fe₃O₄ is a highly magnetic iron oxide. Hydrophobic, strong aerogels composed of magnetite have many possible applications, for example, in cleaning oil spills, where the magnetic properties of the aerogel would help in recovering the aerogel pieces after absorbing the oil. However, the current procedure for making magnetite aerogels yields weak, hydrophilic aerogels, impractical for any industrial use. In this work, we set out to develop a procedure for making the magnetite aerogels stronger and hydrophobic. The modifications were based on previously explored methods of strengthening and hydrophobization of silica aerogel. The first method used in this study was silylation by CTMS (chlorotrimethylsilane) and, separately, by HMDZ (hexamethyldisilazane), in order to hydrophobize the aerogel. The addition of CTMS, both as a liquid during the gel stage and as a gas after the drying, disassociated the magnetite aerogel. The addition of HMDZ does not destroy the aerogel, but the results are yet to be characterized. In another experiment we added PEG (polyethylene glycol) to the aerogel during the sol stage to strengthen it mechanically. The PEG aerogels` density appears to be similar to that of control aerogels, and the shrinkage remains unchanged. The most promising results were obtained from the final experiment, in which we gelated the sol on fiberglass, forming a fiberglass skeleton inside the gel. While not fully characterized yet, the fiberglass based aerogels show much potential, having shrunk very little in comparison to the control aerogels. We believe that fiberglass reinforced-magnetite aerogels may be the ultra-light, strong, stable magnetic material we were searching for.