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Authors
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Grundke, K. ; Michel, S. ; Eichhorn, K.-J. ; Beyerlein, D. ; Bayer, Th.
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Title
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Influence of Chemical Interactions on the Macroscopic Spreading of a Maleic Anhydride Copolymer Melt
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Date
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07.06.2002
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Number
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10102
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Abstract
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We report on wetting experiments of a maleic anhydride copolymer melt on smooth horizontal silicon wafers which were either cleaned or coated with a crosslinked network of a poly(aminosiloxane). The surface properties of the solid substrates have been controlled using contact angle and zeta potential measurements, FT-IR attenuated total reflection (ATR) spectroscopy, and atomic force microscopy. Compared to the bare silicon wafer surface, which had a surface free energy of 61 mJ·m<SUP>-2</SUP> and a weakly acidic surface character due to silanol groups, the poly(aminosiloxane) layer is characterized by basic amino groups at the outermost surface (pH<SUB>IEP</SUB> > 9) and a lower surface free energy (<I><IMGSRC="/giflibrary/12/gamma.gif"BORDER="0"></I><SUB>sv</SUB> = 47 mJ·m<SUP>-2</SUP>). The results of the wetting experiments indicate clearly that macroscopic spreading of the maleic anhydride copolymer melt can be influenced by strong interactions at the solid-liquid interface near the triple line. As could be shown by FT-IR microscopy and spectroscopic ellipsometry, an interfacial chemical reaction takes place between the amino groups available on the solid poly-(aminosiloxane) surface and the anhydride groups of the copolymer melt to form imide structures at the solid-liquid interface during wetting. Due to this interfacial chemical reaction, the spreading process of the maleic anhydride copolymer melt was slowed down and the contact angle was time-dependent indicating a non-equilibrium system. It is also remarkable that lower contact angles were obtained after a certain time of contact compared to the non-reactive system, though the surface free energy of the solid substrate was lower in the reactive system. We assume that the increase of the spreading force at a given spreading speed is due to the release of the free energy during the interfacial reaction, indicating that the chemical reaction is an additional driving force within the spreading process.
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Publisher
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Macromolecular Chemistry and Physics
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Wikidata
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Citation
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Macromolecular Chemistry and Physics 203 (2002) 937-946
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DOI
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https://doi.org/10.1002/1521-3935(20020401)203:7%253C937::AID-MACP937%253E3.3.CO%253B2-3
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Tags
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PG_SurfaceTension
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PG_Wetting_ContactAngle
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