Super-wetting surfaces by plasma- and UV-based grafting of micro-rough acrylate coatings

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• 作者：Thomas Bahners ; Lutz Prager ; Alya Pender ; Jochen S. Gutmann
• 关键词：Super-wetting ; Micro-rough surfaces ; Wenzel equation ; Plasma-grafting ; Photo-grafting
• 刊名：Progress in Organic Coatings
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：76
• 期：10
• 页码：1356-1362
• 全文大小：753 K

文摘

In Wenzel's model of the wetting behavior of rough surfaces, super-wetting can be achieved by micro-roughening a hydrophilic surface, but also by increasing the surface free energy of a micro-rough surface. Therefore, the objective of the present paper was to investigate the effect of grafting post-treatments of micro-rough surfaces having a good mechanical stability. The post-treatments were designed to increase the surface free energy and, accordingly, achieve pronounced surface wetting. Two potential designs of post-treatments were evaluated. A two-step plasma-based surface grafting and a UV-induced photo-chemical grafting.

The plasma-based post-treatment was performed in a two-step process. First, the micro-rough samples were activated in argon or oxygen plasma. The subsequent grafting modification was carried out by immersing the samples in aqueous solutions of p-toluenesulfonic acid, glycerin, and saccharose. For the photo-chemical post-treatment, the micro-rough samples were dipped in an aqueous solution of poly(ethylene glycol) methacrylate (PEG300MA) and irradiated using a UV broadband lamp.

Surface analysis showed that plasma-aided grafting resulted in the lowest water contact angles and extremely wetting surfaces. Following the photo-chemical grafting of PEG300MA, best results were of the order of 20¡ã. In both cases, excellent stability of the layer and its wetting behavior was found.