GOALI - New Nanostructured Polyurethane/POSS Hybrid Films With Enhanced Benefits: From Reactive Aqueous Dispersions to Prescribed Film Morphologies and Properties

该大学(密西西比州南部)和工业(混合塑料公司)合作研究计划将研究在水性聚氨酯(PU)中加入功能性纳米填料(如含有一个或多个官能团的反应性多面体低聚倍半硅氧烷(POSS))的效果，以制备具有潜在固态性能的新型PU/POSS杂化薄膜，这些性能具有增强的生物活性和非凝血性、热稳定性、阻燃性、优异的原子氧环境耐久性以及力学性能的改善。该项目的最终目标是开发关于如何利用杂化PU/POSS组成、温度和流动条件的变化来调整最终产品(如支架、薄膜和高性能保护涂层)的自组装形态以符合规定的大分子结构和性能的新知识，并发明新的应用。此外，该研究还将探讨表征良好的PU/POSS杂化聚合物的结构、流变性能和热机械行为的分子来源。对溶剂浇注PU/POSS薄膜的不同组成、扩链/构型和颗粒大小的函数的研究将使人们能够清楚地了解粒子相互作用的强度和范围的受控变化如何改变PU/POSS杂化体系的相行为、形态和流变性，从而揭示固体PU/POSS杂化薄膜的力学、热力学和动力学行为。这些研究的结果将为检验现有的聚合物形态和分形凝胶自组装理论提供量化基础，这些理论在微观长度尺度上相对较简单的聚合物体系的文献中报道，并可能减少或消除在文献和工业中常见的昂贵的“试错”做法，从而为这类材料提供了一条在纳米尺度上合理设计合成和加工条件的途径。此外，该项目有望发现新的现象，为理论家和计算材料科学家提出新的科学挑战，为化学工程、材料科学与工程和流变学做出重要贡献。此外，从先进的核磁共振和其他表征方法中获得的见解将形成具有增强效益的纳米结构材料的改进设计的基本基础，并用于在反馈机制中控制材料的相结构动力学，该反馈机制将解释作为反应工艺条件的函数的材料改进。靶向PU/POSS杂化材料(不同于传统聚合物、聚合物纳米复合材料和微复合材料)将是有用的，因为PU和POSS的许多固有性质是互补的，它们在未来的高端应用中具有巨大的前景，例如在生物医学设备中，特别是在其他聚合物不可用的心血管接口上。与业界的学术联系将提供批判性指导，并明确关注该项目的相关性。更广泛的影响：这项工作的成果将在国家-S目前对发展微纳尺度材料和加工技术的兴趣发挥重要作用。这些材料不仅具有良好的耐化学性、耐水性、耐溶剂性、韧性、耐磨性、耐久性、良好的熔体/溶液流变性和良好的抗血栓性能，而且具有良好的自组装性能。该项目将为1名博士生提供培训，并为本科生提供研究机会。此外，这项研究可能会导致先进的表征方法的开发，这些方法可以作为聚合物薄膜和分散体基础分析的广泛工具。通过将大学和行业的努力结合起来，这项提议将避免以前试图遵循一种方法而忽视其他方法的令人失望的进展。南密西西比大学有相当多的少数民族学生，他们可以从广泛的聚合物反应工程领域的培训中受益。

CBET-0752150, OtaigbeIntellectual Merit: This university (Southern Mississippi) and industry (Hybrid Plastics Inc.) cooperative research proposal will investigate the effects of incorporating into waterborne polyurethanes (PU) functional nanoscale fillers (such as reactive polyhedral oligomeric silsesquioxanes (POSS) consisting of an eight-corner, -(SiO1.5)n-based cage bearing one or more functional groups) to yield new hybrid PU/POSS films with potential solid-state properties such as enhanced bioactivity & non-thrombogenicity, thermal stability, flame resistance, excellent environmental durability in atomic oxygen, and improvement in mechanical properties. The ultimate goal of the project is to develop new knowledge on how variations in the hybrid PU/POSS composition, temperature and flow conditions can be used to tune the self-assembled morphologies of the final products (such as stents, thin films, and high-performance protective coatings) to prescribed macromolecular structure and properties; and invent new applications. In addition, the research will investigate the molecular origin of the structure, rheological properties and thermomechanical behavior of well-characterized hybrid PU/POSS polymers. Such studies on solvent-cast PU/POSS thin films as functions of different composition, chain extension/configuration, and particle size will enable one to shed light on how controlled changes in the strength and range of particle interactions alter the phase behavior, morphology and rheology of the hybrid PU/POSS system, and consequently on the mechanical, thermal and dynamical behavior of the solid PU/POSS hybrid films. The results obtained from these studies will provide a quantitative basis for testing existing theories on self-assembly of polymer morphologies and fractal gels reported in the literature on relatively simpler polymer systems in the microscopic length scales, and may reduce or eliminate costly "trial and error" practices common in the literature and industry, allowing a route to rational design of synthesis and processing conditions at the nanometer length scale for this class of materials. In addition, the project is expected to discover novel phenomena that will provide new scientific challenges for theorists and computational materials scientists, making an important contribution to chemical engineering, materials science & engineering, and rheology. Further, the insights obtained from the advanced NMR and from other characterization methods will form a fundamental basis for the improved design of nanostructured materials with enhanced benefits and for controlling the phase structure dynamics of the materials in a feedback mechanism that will account for the materials improvements as a function of the reactive processing conditions. The targeted PU/POSS hybrids (which are different from conventional polymers, polymer nanocomposites and microcomposites) would be useful because many of the intrinsic properties of the PU and POSS are complementary, and they hold great promise for future high-end uses such as in biomedical devices, especially at cardiovascular interfaces, where other polymers are not useable. The academic liaison with industry will provide critical guidance and clear focus on relevance of the project. Broader impacts: The results of this work will play an important role in the Nation?s current interest in developing micro- and nano length scale material and processing technologies. The materials are expected to possess desirable morphologies by self-assembly as well as many desirable properties such as good chemical resistance, water resistance, solvent resistance, toughness, abrasion resistance, durability, favorable melt/solution rheology, and good thromboresistant properties, making them widely applicable. The project will provide training for 1 PhD student, as well as provide research opportunities for undergraduate students. In addition, the research may lead to development of advanced characterization methods that can serve as broad-based tools for fundamental analysis of polymeric films and dispersions. By combining university and industrial efforts, this proposal will avoid the disappointing progress seen in prior attempts to follow one approach while neglecting others. The University of Southern Mississippi has a sizable minority student population who could benefit from training in the broad area of polymer reaction engineering.