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Plasma Micro-Nanotextured, Scratch, Water and Hexadecane Resistant, Superhydrophobic, and Superamphiphobic Polymeric Surfaces with Perfluorinated Monolayers
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posted on 2014-05-14, 00:00 authored by Kosmas Ellinas, Sidharam P. Pujari, Dimitrios A. Dragatogiannis, Constantinos A. Charitidis, Angeliki Tserepi, Han Zuilhof, Evangelos GogolidesSuperhydrophobic
and superamphiphobic toward superoleophobic polymeric surfaces of
polymethyl methacrylate (PMMA), polyether ether ketone (PEEK), and
polydimethyl siloxane (PDMS) are fabricated in a two-step process:
(1) plasma texturing (i.e., ion-enhanced plasma etching with simultaneous
roughening), with varying plasma chemistry depending on the polymer,
and subsequently (2) grafting of self-assembled perfluorododecyltrichlorosilane
monolayers (SAMs). Depending on the absence or not of an etch mask
(i.e., colloidal microparticle self-assembly on it), random or ordered
hierarchical micro-nanotexturing can be obtained. We demonstrate that
stable organic monolayers can be grafted onto all these textured polymeric
surfaces. After the monolayer deposition, the initially hydrophilic
polymeric surfaces become superamphiphobic with static contact angles
for water and oils >153°, for hexadecane >142°, and
hysteresis <10° for all surfaces. This approach thus provides
a simple and generic method to obtain superamphiphobicity on polymers
toward superoleophobicity. Hydrolytic and hexadecane immersion tests
prove that superamphiphobicity is stable for more than 14 days. We
also perform nanoscratch and post nanoscratch tests to prove the scratch
resistance of both the texture and the SAM and demonstrate lower coefficient
of friction of the SAM compared to the uncoated surface. Scanning
electron microscope observation after the nanoscratch tests confirms
the scratch resistance of the surfaces.