RUI: Poly (vinyl alcohol) Thin Film Dewetting by Controlled Directional Drying

第1部分：非技术概述聚合物薄膜在日常生活中无处不在。通常，薄膜的稳定性是理想的，例如在涂层材料的应用中。然而，控制脱湿或薄膜破裂也是有益的，例如在印刷和其他平版印刷工艺中。现有的大多数研究都涉及非挥发性和非极性薄膜。从挥发性极性液体（如水）制备聚合物薄膜的稳定性具有实际和基础意义，值得研究。这项研究涉及到用一种叫做吸附自旋铸造的新方法，在硅涂层的硅衬底上制造聚乙烯醇（PVOH）薄膜，PVOH是一种水溶性无毒聚合物。该方法允许PVOH聚合物从水中自发粘附到硅酮表面，以及由于定向水蒸发导致PVOH薄膜的受控破裂。该研究将系统地研究聚合物薄膜稳定性中尚未开发的领域，如极性溶剂的（去）稳定效应，非常规薄膜破裂模式，以及衬底迁移率和极性的影响。作为历史最悠久的女子文理学院的教育家和女科学家，PI致力于提高女性在STEM学科中的代表性和保留率。她将招募并指导一群不同的本科女性，开展本文提出的新的、相关的、可发表的和富有成效的研究。在适当的结构、挑战和支持下，学生将获得在STEM领域未来努力的能力和信心。第二部分：技术概述聚合物薄膜的稳定性和可控脱湿具有实用、技术和基础意义。由于在阐明干燥动力学和溶剂极性对薄膜稳定性的影响方面所涉及的特殊挑战，从水溶液制备聚合物薄膜的研究受到限制。在本研究中，我们将采用一种新的制备方法——吸附自旋铸造，研究聚乙烯醇（PVOH）薄膜在硅片负载的聚二甲基硅氧烷（PDMS）上的脱湿。该方法结合了pdms -溶液界面上PVOH的自发吸附和定向干燥生成有序的PVOH脱湿模式。选择PVOH是因为其可调节的结晶度，这将允许研究一系列的脱湿形态，从传统的液滴到具有独特分形特征的结构。硅片支持的PDMS是衬底的选择，因为它将允许探测衬底的迁移率和极性。本研究的新颖之处在于设计了一种新的聚合物薄膜制备方法，并系统地探索了聚合物薄膜稳定性的相关尚未开发的领域。作为历史最悠久的女子文理学院的教育家和女科学家，PI致力于提高女性在STEM学科中的代表性和保留率。她将招募并指导一群不同的本科女性，开展本文提出的新的、相关的、可发表的和富有成效的研究。在适当的结构、挑战和支持下，学生将获得在STEM领域未来努力的能力和信心。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1: NON-TECHNICAL SUMMARYPolymer thin films are ubiquitous in everyday life. Typically, thin-film stability is desirable, such as in the application of coating materials. However, controlled dewetting or thin-film rupture can also be beneficial, for example in printing and other lithographic processes. Most of the existing studies have involved nonvolatile and nonpolar thin films. The stability of polymer thin films prepared from a volatile and polar liquid, such as water, has practical and fundamental significance and should be investigated. This research involves the fabrication of thin films of poly(vinyl alcohol) (PVOH), a water-soluble and non-toxic polymer, on silicone-coated silicon substrates using a new method called adsorptive spin casting. This method allows the spontaneous adherence of PVOH polymer to the silicone surfaces from water as well as the controlled rupture of PVOH thin films due to directional water evaporation. The study will systematically investigate under- or unexplored areas in polymer thin film stability, such as the (de)stabilization effect of a polar solvent, unconventional thin-film rupture patterns, and the effects of substrate mobility and polarity. As an educator and a female scientist in the longest-standing liberal arts college for women, the PI is committed to improving the representation and retention of women in the STEM disciplines. She will recruit and mentor a diverse group of undergraduate women to carry out new, relevant, publishable, and productive research proposed herein. With the proper structure, challenge and support, the students will gain competency and confidence for their future endeavors in the STEM fields.Part 2: TECHNICAL SUMMARYStability and controlled dewetting of polymer thin films have practical, technological, and fundamental significance. Studies of polymer thin films prepared from aqueous solution have been limited due to the particular challenges involved in elucidating the effects of drying dynamics and solvent polarity on thin-film stability. In the proposed research, poly(vinyl alcohol) (PVOH) thin-film dewetting on silicon wafer-supported polydimethylsiloxane (PDMS) will be studied using a new fabrication method, adsorptive spin casting. This method combines the spontaneous adsorption of PVOH at the PDMS-solution interface and the generation of ordered PVOH dewetting patterns by directional drying. PVOH is chosen because of its tunable crystallinity which will allow the study of a range of dewetting morphologies, from conventional droplets to structures with unique fractal features. Silicon wafer-supported PDMS is the substrate of choice since it will permit the probing of substrate mobility and polarity. The novelties of the research include the design of a new polymer thin-film fabrication method and the systematic exploration of relevant yet under-explored areas in polymer thin-film stability. As an educator and a female scientist in the longest-standing liberal arts college for women, the PI is committed to improving the representation and retention of women in the STEM disciplines. She will recruit and mentor a diverse group of undergraduate women to carry out new, relevant, publishable, and productive research proposed herein. With the proper structure, challenge and support, the students will gain competency and confidence for their future endeavors in the STEM fields.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.