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

非技术概述：聚乙烯醇（PVOH）是一种无毒的水溶性聚合物，它从水溶液中自发地附着在硅酮基底上，形成从纳米级到宏观尺度的“分形”（树枝状）结构。本研究的目的是探讨有机硅衬底上PVOH分形的形成机制，并探讨控制PVOH分形结构特征的材料和实验因素。聚合物分形形成动力学将在其实际生成过程中使用光学显微镜成像；从纳米尺度到微米尺度的分形结构将通过各种显微技术来表征。还将分析吸附PVOH前后有机硅衬底的润湿性和其他表面特性，以评估分形聚合物对衬底性能的影响。申请的资金将在未来三年内支持拟议的科学研究，该研究涉及芒特霍利奥克学院的一些本科生和当地女高中生。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努力做好更好的准备。技术概述：聚乙烯醇（PVOH）从水溶液中自发地吸附到硅酮基底上，并在多个长度尺度上形成不寻常的分形结构。PVOH的结晶性质和有机硅薄膜的独特性质（分子柔韧性、低表面张力和高水相容性）将在探索分形形成的条件中得到探讨。分形特征（尺寸、密度和维数）对实验变量（硅树脂厚度和组成、PVOH分子量和水解程度以及吸附参数）的依赖性也将是拟议工作的重点。利用原子力和光学显微镜对不同有机硅衬底上的PVOH分形进行动态成像，并从纳米尺度到宏观尺度分析其分形特征。除了各种其他表面技术外，还将利用接触角测量和椭偏测量来表征有机硅衬底吸附PVOH前后的特性，以评估分形吸附聚合物对衬底表面化学和性能的影响。本研究不仅将建立一个新的体系来制备具有可控结构特征的分形支化聚合物，而且将为分形聚合物的形成提供材料和实验要求方面的见解。申请的资金将在未来三年内支持包括芒特霍利奥克学院的一些本科生和当地女高中生在内的研究。

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.