Developing superhydrophobic and oleophobic nanostructure by a facile chemical transformation of zirconium hydroxide surface

Stable hydro/oleo-phobic and superhydrophobic nanopowders, useful for self-cleaning applications, are synthesized at room temperature by modifying Zr(OH)(4)center dot nH(2)O with a very low surface-energy molecule-1H,1H,2H,2H-perfluorododecyltrichlorosilane whose long chain {-(CH2)(2)(CF2)(9)CF3 moiety (PFD)} serves as surface-protrusion. The PFD-content is varied over 3.6-18.7 wt% in optimizing a hydrophilic to hydro/oleo-phobic or even to superhydrophobic transformation. Two halos in the X-ray diffraction pattern of amorphous Zr(OH)(4)center dot nH(2)O are accompanied by a peak at 20=18.0 which grows in intensity progressively as the PFD-content increases from 5.2 to 18.7 wt%. The peak corresponds to -CF2-CF2-crystalline order (10-20 nm) at the PFD-functionalized surface. The microstructure shows Zr(OH)(4)center dot nH(2)O as a cloud-like phase, bonded to plate-like sheaths (PFD moiety). The C-F stretching bands at 1150 and 1210 cm(-1) grow in intensity relative to that of O-H stretching at 3460 cm(-1) in proportion to the PFD-content. An 18.7 wt% PFD-functionalized sample exhibits a high contact angle CA=153 degrees for water (contact angle hysteresis =4 degrees and roll-off angle <4 degrees), together with CA=132 degrees for glycerol, CA=130 degrees for diethylene glycol, and CA=113 degrees for n-hexadecane, supporting good superhydrophobicity and oleophobicity. Surface-energy reduction due to PFD moiety together with an optimal spacing between the surface-protrusions explains the water/organic liquid repellency. (C) 2015 Elsevier B.V. All rights reserved.