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Wetting/dewetting behavior of lightly sulfonated polystyrene ionomers on solid surfaces.

机译：轻度磺化的聚苯乙烯离聚物在固体表面上的润湿/去润湿行为。

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摘要

The primary objective of this study was to improve the interfacial wetting properties of the solid surface by developing a uniform, robust film of random sulfonated polystyrene (SPS) ionomer. Meanwhile, to ascertain the mechanism of the suppression of dewetting---i.e., is it thermodynamic or rheological in origin, was our second goal.;The wetting/dewetting behavior of thin films of low molecular weight SPS ionomers spin-coated onto silica surfaces were studied using atomic force microscopy (AFM), contact angle measurements, and electron microscopy. The effects of the sulfonation level, the choice of the cation, the solvent used to spin-coat the films, and the molecular weight of the ionomer were investigated. The addition of the sulfonate groups suppressed the dewetting behavior of the PS above its glass transition temperature. Increasing the sulfonation level led to more homogeneous and smoother surfaces. The choice of the cation used affected the wetting properties, but not in a predictable manner.;The octadecyltrichlorosilane (OTS)-modified silica surface was employed as a hydrophobic substrate to investigate the mechanism of wetting behavior of SPS. The complex between the ionic groups of ionomers and the --Si-O- groups on the surface of the silicon wafer was very critical for better wetting behaviors of a lower sulfonated Lithium ionomer (2.5LiSPS4), while ionic aggregation between ionomer molecules with a higher sulfonation level (6.5LiSPS4) played an important role for the suppression of dewetting.;Rough surfaces composed of discrete but relatively uniform nanoparticles were prepared from a lightly sulfonated polystyrene ionomer by spin coating from tetrahydrofuran (THF) or a THF/methanol mixture onto a silica surface. The particle morphology is consistent with the spinodal decomposition of the film surface occurring during spin coating. The particles are well wetted to the silica, and if heated for a long time above the ionomer's glass-transition temperature, the particles flow and coalesce into a smooth, homogeneous film. The size distribution of particles at the air/solid interface are influenced by the types of solvent, sulfonation level, the counterions and the substrate based on our current research.
机译：这项研究的主要目的是通过开发均匀，坚固的无规磺化聚苯乙烯（SPS）离聚物薄膜来改善固体表面的界面润湿性。同时，确定抑湿的机理是我们的第二个目标。即，将低分子量SPS离聚物的薄膜旋涂在二氧化硅表面上，其润湿/去湿性能是我们的第二个目标。使用原子力显微镜（AFM），接触角测量和电子显微镜进行了研究。研究了磺化水平，阳离子的选择，用于旋涂膜的溶剂以及离聚物分子量的影响。磺酸根基团的加入抑制了PS在其玻璃化转变温度以上的去湿行为。磺化水平的提高导致表面更均匀，更光滑。所用阳离子的选择会影响润湿性能，但不是以可预测的方式。；十八烷基三氯硅烷（OTS）改性的二氧化硅表面被用作疏水性底物，以研究SPS润湿行为的机理。离聚物的离子基团与硅片表面上的--Si-O-基团之间的络合物对于较低磺化锂离聚物（2.5LiSPS4）的更好润湿行为至关重要，而离聚物离子分子之间的离子聚集则为较高的磺化水平（6.5LiSPS4）在抑制反润湿中起着重要作用。;由轻度磺化的聚苯乙烯离聚物通过将四氢呋喃（THF）或THF /甲醇混合物旋涂到表面上，制备出由离散但相对均匀的纳米颗粒组成的粗糙表面二氧化硅表面。颗粒形态与旋涂期间发生的膜表面的旋节线分解一致。颗粒被二氧化硅充分润湿，如果长时间加热到离聚物的玻璃化转变温度以上，颗粒会流动并聚结成光滑均匀的薄膜。根据我们目前的研究，气/固界面处的颗粒尺寸分布受溶剂类型，磺化水平，抗衡离子和底物的影响。

著录项

  • 作者

    Zhai, Xiaowen.;

  • 作者单位

    University of Connecticut.;

  • 授予单位 University of Connecticut.;
  • 学科 Chemistry Polymer.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 108 p.
  • 总页数 108
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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