RUI: Fractal Structure Formation from Poly(vinyl alcohol) Adsorption on Silicone Substrates

非技术综述：聚乙烯醇(PVOH)是一种无毒、可溶于水的聚合物，从水溶液中自发地附着在硅胶衬底上，形成从纳米到宏观的“树枝状”结构。本工作的目的是探索在有机硅衬底上形成PVOH分形的机理，并探索控制PVOH分形结构特征的材料和实验因素。在聚合物的实际生成过程中，将使用光学显微镜对其形成动力学进行成像；从纳米到微米尺度的分形结构将通过各种显微技术来表征。此外，还将分析硅胶基板在PVOH吸附前后的润湿性和其他表面特征，以评估分形聚合物对基板性能的影响。申请的资金将在未来三年支持拟议的科学研究，该研究涉及蒙霍利奥克学院的一些本科生和当地的女高中生。通过适当的培训、指导和鼓励，学生将获得科学研究的能力和信心，并为下一阶段的教育工作做好更好的准备。技术摘要：聚乙烯醇(PVOH)自发地从水溶液中吸附到硅胶衬底上，并在多个长度尺度上形成不寻常的分形结构。我们将探讨PVOH的结晶性质和有机硅薄膜的独特性质(分子柔性、低表面张力但高水相容性)，以探索形成分形的条件。分形特征(大小、密度和维度)与实验变体(硅胶厚度和组成、PVOH相对分子质量和水解度以及吸附参数)的相关性也将是拟议工作的重点。原子力和光学显微镜将被用来在不同的有机硅衬底上动态地成像PVOH的分形形成，并分析从纳米尺度到宏观尺度的分形特征。接触角测角法和椭偏仪，以及其他各种表面技术，将被用来表征PVOH吸附前后的有机硅基板，以评估吸附的聚合物对基板表面化学和性能的影响。这项研究不仅将建立一种制备具有可控结构特征的分支化聚合物的新体系，而且还将为形成分形化聚合物的材料和实验要求提供见解。申请的资金将在未来三年支持涉及芒特霍利奥克学院的一些本科生和当地女高中生的研究。

NON-TECHNICAL SUMMARY:Poly(vinyl alcohol) (PVOH), a nontoxic and water-soluble polymer, spontaneously attaches itself to silicone substrates from water solution and forms "fractal" (tree-branch like) structures from nanoscopic to macroscopic scales. The objectives of the proposed work are to explore the formation mechanism of PVOH fractals on silicone substrates and to probe the material and experimental factors controlling the structural features of PVOH fractals. The polymer fractal formation dynamics will be imaged during their actual generation using optical microscopy; the fractal structures from the nanometer to micrometer scales will be characterized by various microscopy techniques. Wettability and other surface characteristics of the silicone substrates, before and after PVOH adsorption, will also be analyzed to assess the effect of the fractal polymers on substrate properties. The funds requested will support the proposed scientific research involving a number of undergraduate students at Mount Holyoke College and local female high school students over the next three years. With the proper training, mentoring, and encouragement, the students will gain competency and confidence in scientific research and will be better prepared for the next phase of their educational endeavors.TECHNICAL SUMMARY:Poly(vinyl alcohol) (PVOH) spontaneously adsorbs from aqueous solution to silicone substrates and forms unusual fractal structures at multiple length scales. The crystalline nature of PVOH and the unique properties of silicone thin films (molecular flexibility, low surface tension but high water compatibility) will be probed in exploring the conditions for fractal formation. The dependence of fractal features (size, density, and dimensionality) on experimental variants (silicone thickness and composition, PVOH molecular weight and degree of hydrolysis, and adsorption parameters) will also be the focus of the proposed work. Atomic force and optical microscopy will be used to image dynamically PVOH fractal formation on various silicone substrates in-situ and to analyze the fractal features from nanoscopic to macroscopic scales. Contact angle goniometry and ellipsometry, in addition to various other surface techniques, will be utilized to characterize the silicone substrates, before and after PVOH adsorption, to assess the effect of the fractal adsorbed polymers on substrate surface chemistry and properties. The proposed research will not only establish a new system to prepare fractally branched polymers with controlled structural features, but will also provide insights on material and experimental requirements for fractal polymer formation. The funds requested will support research involving a number of undergraduate students at Mount Holyoke College and local female high school students over the next three years.