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

二氧化硅玻璃因其光学特性以及化学和热稳定性而受到重视，已有 2000 多年的历史，使其成为表面涂层的天然候选者。目前的方法，例如化学气相沉积或传统的溶胶-凝胶处理，通常需要能源昂贵的高真空或高温方法。该合作项目旨在将新型溶胶凝胶材料“熔融凝胶”的创新与电喷雾沉积相结合，以创造材料高效、耐用的混合玻璃涂层。熔化的凝胶在低温下转变为这些混合玻璃，从而可以使用通常不被考虑的基材，例如对于连续制造至关重要的聚合物网。与电喷雾（一种工业上接受的静电制造技术）相结合，可以在复杂的三维表面上形成薄（微米级）涂层，并在环境加工条件下轻松加入添加剂。该奖项有助于对关键工艺设置和所得涂层特性（例如机械、电气、化学和/或生物）的基本了解，这些特性是各种涂层应用所需的。这项研究的结果有利于航空航天、航海、汽车和医疗植入领域的工业应用，这将有利于美国经济。该项目为来自较小的西班牙裔服务机构和主要研究机构的学生提供了合作和参与多学科研究的机会。熔融凝胶是通过溶胶-凝胶工艺制成的低聚倍半硅氧烷材料，其固结温度在 120 至 170 摄氏度范围内，其中熔融凝胶分解并交联成不可逆的杂化有机改性二氧化硅网络。 熔融凝胶及其混合玻璃伙伴是使用软化学方法合成的，该方法允许有机部分与无机网络直接共价键合。 电喷雾沉积是一种在高电场中传递均匀带电微滴的方法，可对熔融凝胶的微米级至纳米级结构提供必要的动态控制，以实现卓越的涂层性能。然而，电荷注入和喷雾极性对溶胶-凝胶的影响目前尚不清楚。 这项研究改变了这些参数以及熔化凝胶固结温度和固有电荷，以通过主要的机械和光谱分析来识别固结机制的变化。 然后将这些效果与涂层的最终性能联系起来。该资助团队由两名合作伙伴组成，结合溶胶-凝胶化学和电喷雾沉积专业知识，创建了一种用于合成、加工和性能表征的整体方法。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点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.