In situ synthesis of nanolamellas of hydrophobic magnesium hydroxide

Hydrophobic magnesium hydroxide (Mg(OH)2) nanoparticles are prepared by in situ surface modification method with oleic acid (C17H33COOH, OA) as surface modifier. This reaction proceeds in aqueous solution and includes two processes: the Mg(OH)2 crystal growth and the surface modification. The Mg(OH)2 nanoparticles exhibit a lamella morphology with an average width of 60 nm and thickness of 19 nm. These nanolamellas have wormhole-like pores as small as 3.7 nm. The surface modification starts from the C17H33COO− groups, derived from OA molecules in alkaline milieu, substituted the surface adsorbed –OH groups on Mg(OH)2 nanolammellas. The C17H33COO− groups are finally adsorbed onto Mg(OH)2 nanoparticles with a stable chemical bond. Compared with unmodified blank Mg(OH)2 product, the product obtained with this method possesses excellent hydrophobic properties such as a high water contact angle of 121° and a well dispersion.