Effect of end-groups on simultaneous oleophobicity/hydrophilicity and anti-fogging performance of nanometer-thick perfluoropolyethers (PFPEs)Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ra04483a

Simultaneously oleophobic/hydrophilic coatings are highly desirable in many important applications, e.g. , anti-fogging. However, to date, such coatings have been rarely reported and the underlying mechanisms remain unclear. In the current paper, the wetting behavior of three nanometer-thick perfluo...

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Main Authors: Wang, Yongjin, Knapp, James, Legere, Aleigh, Raney, Jacob, Li, Lei
Format: Article
Language:English
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Summary:Simultaneously oleophobic/hydrophilic coatings are highly desirable in many important applications, e.g. , anti-fogging. However, to date, such coatings have been rarely reported and the underlying mechanisms remain unclear. In the current paper, the wetting behavior of three nanometer-thick perfluoropolyether (PFPE) polymers with the same backbone but different end-groups has been studied by contact angle tests and the underlying mechanisms governing the simultaneous oleophobicity/hydrophilicity have been investigated. The experimental results indicated that the end-groups of the nanometer-thick PFPEs are critical to the simultaneous oleophobicity/hydrophilicity. PFPE polymers with different end-groups can interact with the substrate in very different ways, resulting in different packing orders and thus different inter-chain distances within the polymer nanofilms. If the inter-chain distance is appropriately small, smaller water molecules penetrate the nanofilms quickly while larger oil molecules penetrate the nanofilms much more slowly. As a result, the surface shows a higher oil contact angle (OCA) than WCA, i.e. , simultaneous oleophobicity/hydrophilicity. Moreover, the effect of simultaneous oleophobicity/hydrophilicity on the long-term anti-fogging capability has been studied by X-ray photoelectron spectroscopy (XPS) and anti-fogging tests. The results indicated that the unique simultaneous oleophobicity/hydrophilicity reduces the airborne hydrocarbon contamination and therefore improves the long-term anti-fogging performance. Simultaneously oleophobic/hydrophilic coatings are highly desirable in many important applications, e.g. , anti-fogging.
ISSN:2046-2069
DOI:10.1039/c5ra04483a