Controlling silicone polyHIPE materials properties with triblock copolymer surfactants: A route to bottom-up synthesis of metamaterials

非技术概述：超材料是一种人造材料，具有非凡的物理特性，被提议用于音障、制造超高分辨率的超级透镜、制造隐形斗篷和其他新兴领域。这项研究的目的是产生新的、可定制的超材料，这种材料可以很容易地扩大规模，而不依赖于复杂和昂贵的方法。具体来说，这项工作将生产多孔聚硅材料，并对用于制备多孔材料的聚合物结构如何控制其作为软超材料的性能产生基本的理解。除了对超材料研究的预期积极影响外，这项工作的发现还将使研究生物医学和再生医学应用的多孔材料以及新型硅树脂材料的科学家受益。美国还非常需要拥有世界一流技能的多元化、全球参与的劳动力。预计这批劳动力将提高美国在研究和教育方面的领先地位，并增强国家经济竞争力。本提案中的活动将包括辛辛那提大学和波尔多大学之间的国际合作研究机会。这将包括辛辛那提大学的两名本科生前往法国参加与超材料专家的实践研究经验。每年将评价国际经验的有效性，并通过会议发言和科学论文传播结果。技术概述：超材料的制造主要是通过自上而下的光刻方法实现的，这种方法很难按比例放大。另外，使用有机硅聚合高内相乳剂（polyHIPEs），一种自下而上的制造光学和声学超材料的策略是可能的。这项研究的目的是产生新的、可定制的超材料。在这个项目中测试的中心假设是，嵌段共聚物表面活性剂的结构和功能控制了硅水乳液的稳定性和性能，从而产生了聚hipes，从而控制了最终的超材料性能。中心假设将通过追求以下具体目标来验证：目标1：确定多孔性、存储模量和硅树脂聚苯乙烯的阻尼如何控制材料内的声速，这是硅树脂中水乳液结构的结果。目的2：制备聚合物交联剂作为硅水包水乳液的表面活性剂，以保持硅树脂polyHIPE的孔隙率和压缩性，并稳定polyHIPE中的金纳米颗粒。这些目标的实现有望为两亲性嵌段聚合物表面活性剂化学如何用于制备新型多孔硅树脂聚苯乙烯材料奠定基础。这是及时和重要的，因为它可以负担得起可调的、简单的、相对便宜的声学超材料，用于成像、隐形和长波降噪。参与这项研究的研究生和本科生将接受高分子化学、材料合成和表征方面的培训，并将参与国际合作研究。该奖项反映了美国国家科学基金会的法定使命，并通过基金会的智力价值和更广泛的影响审查标准进行了评估，认为值得支持。

NON-TECHNICAL SUMMARY:Metamaterials are human-made materials that possess extraordinary physical properties and have been proposed for use as sound barriers, creating super-lenses of remarkable resolution, making invisibility cloaks, and other emerging areas. The objective of this research is to generate new, tailorable, metamaterials in ways that can be easily scaled up and do not rely on complex and expensive approaches. Specifically, this work will produce porous polysilicone materials and generate fundamental understanding of how the structure of polymers used to prepare the porous materials can control their performance as soft metamaterials. In addition to the expected positive impact on metamaterials research, the findings from this work will also benefit scientists studying porous materials used for biomedical and regenerative medicine applications and new silicone materials. There is also a great need for a diverse, globally engaged U.S. workforce possessing world-class skills. This workforce is expected to enhance U.S. leadership in research and education and strengthen national economic competitiveness. The activities in this proposal will include international collaborative research opportunities between the University of Cincinnati and the University of Bordeaux. This will include a trip to France for two undergraduate students from the University of Cincinnati to participate in hands-on research experiences with experts on metamaterials. The effectiveness of the international experiences will be evaluated each year and the results disseminated though conference presentations and scientific papers.TECHNICAL SUMMARY:The fabrication of metamaterials is largely achieved by top-down lithography approaches, which are difficult to scale-up. Alternatively, a bottom-up strategy to make optical and acoustic metamaterials is possible using silicone polymerized high-internal-phase emulsions (polyHIPEs). The objective of this research is to generate new, tailorable, metamaterials. The central hypothesis tested in this project is that the structure and functionality of block copolymer surfactants control the stability and properties of water-in-silicone emulsions and thus the resulting polyHIPEs, and hence the final metamaterials properties. The central hypothesis will be tested by pursuing the following specific aims: Aim 1: Determine how the porosity, storage moduli, and damping of silicone polyHIPEs control the speed of sound within the material as a result of the structure of water-in-silicone emulsions. Aim 2: Prepare polymer cross-linkers as surfactants for water-in-silicone emulsions to maintain porosity and compressibility of silicone polyHIPEs and stabilize gold nanoparticles within the polyHIPE. Accomplishment of these Aims is expected to establish how amphiphilic block polymer surfactant chemistry can be used to prepare new porous silicone polyHIPE materials. This is timely and important, as it could afford tunable, simple, and relatively cheap acoustic metamaterials for applications in imaging, cloaking, and long-wavelength noise reduction. The graduate and undergraduate students engaged in this research will be trained in polymer chemistry, materials synthesis and characterization, and will participate in international collaborative research..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.