Presented is an investigation of surface morphology of arrayed MoO_x structures with increasing aspect ratios, and their resultant superhydrophillic, and their modified superhydrophobic properties. Molybdenum oxide (MoO_x) submicron structures were grown on lithium niobate (LiNbO₃) substrates via the thermal evaporation of MoO₃ nanopowder at 750°C in a horizontal tube furnace. A mixture of 90% argon and 10% oxygen was introduced into the thermal evaporation tube at flow rate of 1L/min. This resulted in the formation of a white film which consisted of submicron tabular structures. Scanning electron micrographs revealed that the tabular molybdenum oxide grew in arrays 80-100° with respect to the plane of the substrate, with tabular structures with a thickness of approx 0.5 - 1.5μm. Initial testing of MoO_x structures revealed that they were extremely super hydrophilic. Such MoO_x arrays were coated with fluoropolymer Teflon, deposited using the RF sputtering technique. The addition of a semi-conformal Teflon layer effectively converts the superhydrophilic MoO_x layer into a superhydrophobic surface. These superhydrophobic surfaces exhibit contact angles with aqueous media in excess of 150°. Such surfaces can be utilized for the selective adsorption and desorption of protein or pharmacokinetic molecules, with applications in drug delivery and biomedical systems.

Date Published: 27 December 2007
PDF: 8 pages
Proc. SPIE 6799, BioMEMS and Nanotechnology III, 67990F (27 December 2007); doi: 10.1117/12.759867

Published in SPIE Proceedings Vol. 6799:
BioMEMS and Nanotechnology III
Dan V. Nicolau; Derek Abbott; Kourosh Kalantar-Zadeh; Tiziana Di Matteo; Sergey M. Bezrukov, Editor(s)