Fabrics with Tunable Oleophobicity

Advanced Materials (Impact Factor: 17.49). 06/2009; 21(21):2190 - 2195. DOI: 10.1002/adma.200802502

ABSTRACT A study was conducted to investigate the effects of nonwetting design parameters on fabrics with tunable oleophenobicity. A simple dip-coating process was developed for delivering a conformal coating of polyhedral oligomeric silsesquioxane (POSS) molecules recognizing the role of re-entrant surface features. The coating enabled researchers to apply enhanced liquid repellency to any substrate possessing re-entrant textures, such as the lotus leaf, commercial fabrics, and duck feathers. It was observed that a non-wetting drop completely wetted into the fabric texture beyond a critical imposed strain, leading to near-zero contact angles. This process allowed to develop surfaces that exhibited reversible deformation-dependent and tunable wettability, including the capacity to switch their surface wetting properties against a wide range of polar and nonpolar liquids.

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    • "Normally, the trapped air in the gaps of patterned surfaces restrains the spread of a water droplet, causing it to bead up, but the low surface tension of oil (surface tension is around 20–30 mJ/m 2 while surface tension of water is 72.8 mJ/m 2 ) would wet the patterned surface by breaking the air-pillar barrier and flow into the gaps [27] [28] [29] [30]. In order to achieve superhydro-oleophobicity, fluorine compound with a high percentage of CF 3 and CF 2 groups have been applied to reduce the surface tension of the patterned surface [13] [16] [19] [30] [31]. The most widely reported technique to fabricate oleophobic materials is to deposit a self-assembled monolayer (SAM) of fluorocarbon onto the patterned surface through vapor deposition [31–36]. "
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    ABSTRACT: In this work we render superhydro-oleophobic properties to the surface of polydimethylsiloxane (PDMS) elastomer through bio-inspired micropillar surface and chemical modification with a fluorosilane polymer, trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS). Two different chemical modification approaches were applied on both flat and micropillar PDMS: (1) vapor deposition of FDTS on cured PDMS surface, and (2) blending FDTS with the liquid PDMS precursor before curing. Comparative studies of the water and oil contact angles on the neat and FDTS-modified PDMS (both flat and micropillar) indicated that superhydro-oleophobicity was delivered by a combination of FDTS chemistry and micropillar geometry. FDTS-blended PDMS micropillar displayed better oleophobicity with an oil contact angle of ∼141° than FDTS-coated PDMS micropillar (∼115°). In contrast to the smooth surface of FDTS-blended PDMS micropillar, rough surface with some structure defects were found on the FDTS-coated micropillar surface caused by the vapor deposition process; the surface defects might be responsible for the observed low oleophobicity of FDTS-coated PDMS micropillar. Superhydrophobicity of FDTS-blended PDMS micropillar in terms of water contact angles was found to be independent of the quantity of FDTS. However, the oleophobicity of FDTS-blended PDMS micropillar was found to be dependent of the quantity of FDTS; with the increased weight concentration of FDTS in PDMS, the oils contact angle first increased and then leveled out at a finite concentration. FTIR and XPS were applied to analyze surface chemistry information suggesting the blended FDTS segregated from bulk PDMS and enriched at the surface to reduce surface tension so as to make surface super-oleophobic.
    Applied Surface Science 11/2014; 324. DOI:10.1016/j.apsusc.2014.10.146 · 2.71 Impact Factor
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    • "Hence for a given liquid, the CA can be tuned either by creating periodically or randomly distributed micro-nanostructures and/or by engineering the surface chemistry (surface energy) of the solid. There are plenty of reports in the literature that systematically discuss the impact of surface texture on wettability [13] [14] [15] [16] [17] [18] [19] [20]. Low-surface energy fluorine-containing polymeric coatings have been extensively studied to create superhydrophobic surfaces with water contact angle (WCA) higher than 150° due to their anti-contamination and self-cleaning properties desirable for many industrial and biological applications [21] [22] [23] [24] [25]. "
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    ABSTRACT: Understanding and tuning the wettability of the surfaces are highly intriguing for various applications. The development of stable and transparent coatings over aluminium alloys and glass substrates for making them superhydrophobic and extended oleophobic (lower to the surface tension of 33.4 mN/m (coconut oil)) using a scalable and simple spray painting technique is demonstrated. Fluorinated graphene oxide (FGO, fluorine content of 34.4 atomic weight %), an atomically layered material, modified Polydimethylsiloxane (PDMS) polymer composite is used as the paint for the coatings. The coated films were studied for their surface and compositional features. A water contact angle (CA) of 173.7o (close to the highest ever reported water CA, 175o) is achieved with 60 wt% FGO in PDMS, and the same showing a CA of 94.9o with coconut oil, in conjunction with a low contact angle hysteresis (4o). The work of adhesion with the amount of FGO is studied and the surface energy of FGO containing paints is calculated and compared with the bare paints using Zisman plot analysis.
    Carbon 01/2014; 84(1). DOI:10.1016/j.carbon.2014.12.004 · 6.20 Impact Factor
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    • "The latter mixture of solids has been used previously for treating fabrics by dip coating in AK225G [31]. Four test conditions involved a single dip coating in each of the four solutions described above. "
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    ABSTRACT: Breakthrough pressure is an important parameter associated with the performance of water-resistant fabrics. Hydrostatic testing has been utilized to experimentally determine the breakthrough pressure of commercial cotton fabrics treated with various combinations of octakis(1H,1H,2H,2H-perfluorodecyl) polyhedral oligomeric silsesquioxane (F-POSS), a compound with the lowest reported solid surface energy, and the commercial fluoroelastomer, Tecnoflon®. The breakthrough pressure values (amounting to a few inches of water) were found to be similar to predicted values based on the geometry of the samples and the surface energy of the components. The theoretical predictions, however, do not explain all differences observed among samples, such as the fact that a single dip coating with both F-POSS and Tecnoflon® produced a higher breakthrough pressure than a single dip coating in either F-POSS or Tecnoflon®, or sequential dip coating (in either order) of the two components. SEM analysis of the coated fabrics indicated that coatings were conformal at the microscale, but did result in sub-micron scale roughness. Although this roughness may help to increase the contact angles with water, the breakthrough pressure appeared to be primarily determined by the geometry of the individual filaments.
    Applied Surface Science 06/2012; 258(24):10205-10208. DOI:10.1016/j.apsusc.2012.06.064 · 2.71 Impact Factor
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