Collaborative Research: Electrospray Deposition of 'Melting Gels' for Multifunctional Coatings

二氧化硅玻璃因其光学性能以及化学和热稳定性而受到2000多年的重视，使其成为表面涂层的天然候选者。目前的方法，如化学气相沉积或传统的溶胶-凝胶工艺，通常需要耗能高的高真空或高温方法。该合作项目寻求将一种新型的溶胶凝胶材料“熔融凝胶”的创新与电喷雾沉积相结合，以创造出材料高效、耐用的混合玻璃涂层。熔融凝胶在低温下转化为这些混合玻璃，从而能够使用通常不会考虑的基材，例如对连续制造至关重要的聚合物网。与电喷雾(一种工业接受的静电制造技术)相结合，可以在复杂的三维表面上轻松地加入添加剂，在环境处理条件下实现(微米级)薄涂层。该奖项有助于从根本上了解各种涂层应用所需的关键工艺设置和由此产生的涂层性能(例如，机械、电气、化学和/或生物)。这项研究的结果有利于航空航天、航海、汽车和医疗植入物行业的工业应用，这将有利于美国经济。该项目为一家规模较小的拉美裔服务机构和一家大型研究机构的学生提供了合作和从事多学科研究的机会。熔融凝胶是通过溶胶-凝胶法制备的低聚倍半硅氧烷材料，其固化温度在120至170摄氏度之间，熔融凝胶在其中分解并交联成不可逆杂化的有机改性二氧化硅网络。熔融凝胶和它们的混合玻璃伙伴是使用软化学方法合成的，这种方法允许有机部分直接共价连接到无机网络。电喷雾沉积是一种在高电场中提供均匀带电微滴的方法，它提供了必要的动态控制熔融凝胶的微米到纳米级的结构，以获得优异的涂层性能。然而，电荷注入和喷雾的极性对溶胶-凝胶的影响目前还不清楚。本研究主要通过力学分析和光谱分析，改变这些参数随熔融凝胶固结温度和本征电荷的变化，以确定固结机理的变化。然后将这些影响与涂层的最终性能联系起来。这项奖励的团队由两名合作伙伴组成，他们结合了溶胶-凝胶化学和电喷雾沉积的专业知识，为合成、加工和性能表征创造了一种全面的方法。这项奖励反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Silica glass has been valued more than 2000 years for its optical properties and chemical and thermal stability, making it a natural candidate for surface coatings. Current methods, such as chemical vapor deposition or conventional sol-gel processing, often require energy-costly high vacuum or high temperature methods. This collaborative project seeks to couple innovations in a new class of sol gel materials, 'melting gels', with electrospray deposition to create materials-efficient, durable hybrid glass coatings. Melting gels transform into these hybrid glasses at low temperatures enabling the use of substrates that would not normally be considered, such as polymer webs that are key for continuous manufacturing. The combination with electrospray, a type of industrially-accepted electrostatic manufacturing technology, enables thin (microscale) coatings on complex three-dimensional surfaces with facile incorporation of additives in ambient processing conditions. This award contributes fundamental understanding of the key process settings and the resulting coating properties (e.g. mechanical, electrical, chemical, and/or biological) that are desirable for a wide variety of coating applications. Results from this research benefits industrial applications in aerospace, nautical, automotive, and medical implant sectors, which would benefit U.S. economy. This project provides opportunities for students from a smaller Hispanic-serving institution and a major research institution to collaborate and engage in multidisciplinary research. Melting gels are oligomeric silsesquioxane materials made by a sol-gel process that possess consolidation temperatures in the range of 120 to 170 degree C, where the melting gels decompose and crosslink into an irreversible hybrid organically-modified silica network. Melting gels and their hybrid glass partners are synthesized using a soft-chemistry approach that allows for direct covalent bonding of organic moieties to the inorganic network. Electrospray deposition, a means of delivering uniform charged microdroplets in a high electric field, provides the necessary dynamic control of the micro- to nano-scale structure of melting gels to achieve superior coating properties. However, the effects of the charge injection and polarity of the spray on the sol-gel are currently unknown. This research varies these parameters along with the melting gel consolidation temperature and intrinsic charge to identify changes in the consolidation mechanism through primarily mechanical and spectroscopic analysis. These effects are then be connected to the final performance of the coatings. The team for this grant consists of two partners, combining sol-gel chemistry and electrospray deposition expertise to create a holistic approach for synthesis, processing, and property characterization.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.