ERASE-PFAS: Bottom-up synthesis of polymeric membranes for PFAS sequestration

防腐防污涂料越来越多地出现在我们的日常生活中，促进了物体和/或材料的清洁，减缓了材料的劣化，并保护它们免受化学或热应力的影响。自然，随着这些涂料性能的提高，它们对公众日益增长的需求变得更具吸引力，从而推动了它们的制造。构成这些涂层的一大类分子是全氟烷基和多氟烷基物质（PFAS）。已经确定了数千种PFAS，其中一些是大规模生产的。PFAS固有的化学特性使它们在泄漏到生态系统中时基本上是牢不可破的。不幸的是，美国各地饮用水中PFAS的存在已经得到了充分的证明，人类摄入PFAS与许多疾病和癌症有关。摆在我们面前的巨大挑战是找到从环境中去除PFAS的方法，特别是当这些物质污染了饮用水源时。该项目的目标是开发能够过滤水的合成膜，以去除大部分PFAS，使其远远低于美国环境保护署规定的70万亿分之一的阈值。成功完成拟议的研究将发展化学途径和基本认识，以创造高性能膜，从水中去除PFAS，最终实现保护公众健康的目标。通过教育和培训，包括莱斯大学的两名研究生的指导，将实现对社会的额外效益。全氟烷基和多氟烷基物质（PFAS）通常是由1)阴离子头基、羧酸盐或磺酸盐组成的分子；2)氟化骨架，它对环境退化具有不可思议的抵抗力。它们的化学稳定性和热稳定性使它们成为保护材料免受降解或火灾等事件影响的理想物质。在世纪之交，由于与健康有关的影响，某些物种开始被禁止使用。然而，大量的生产加上它们在环境中的持久性导致了环境，特别是饮用水源的广泛污染。文献记载的PFAS对人类健康造成的风险包括孕妇严重畸形、成人癌症、肝功能障碍、甲状腺疾病、生育能力下降、高胆固醇和肥胖。考虑到PFAS对大多数化学吸附剂的亲和力和结合能力较弱，未来的挑战是设计能够将它们从污染水中去除的膜。该项目的总体目标是设计阴离子PFAS的识别位点，该位点将在稍后开发并纳入用于过滤水的膜中，以隔离长链和短链PFAS。为了实现这一核心目标，该项目将1)设计嵌入在超分子支架中的识别位点；2)合成、表征和确定最有前途的支架的阴离子结合性能；3)通过将烯烃和/或环氧化物官能团整合到超分子支架中，聚合最有希望的结构，并在水样品中测试其PFAS隔离性能。该项目的成功完成将为增强PFAS在分子支架内的结合建立基本参数，从而将这些知识转化为聚合物过滤材料的设计。教育和推广活动包括为高中生和本科生举办研讨会和实践讲习班。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。

Anti-corrosion and anti-stain coatings have been increasingly present in our daily lives facilitating the cleaning of objects and/or materials, slowing down material’s deterioration, and protecting them against chemical or thermal stress. Naturally, as these coatings increase in performance, they become more attractive to the public increasing demand, and thus driving forward their manufacture. One large class of molecules forming part of these coatings are the per- and polyfluoroalkyl substances (PFAS). Several thousands of PFAS have been identified, some of which are made in a very large scale. The inherent chemical properties of PFAS makes them essentially unbreakable when they leak into ecosystems. Unfortunately, the presence of PFAS in drinking water across the U.S. is now well-documented and human ingestion of PFAS has been associated with a number of diseases and cancer. The grand challenge ahead of us is to find ways of removing PFAS from the environment, especially when these substances contaminate drinking water sources. The goal of this project is to develop synthetic membranes capable of filtering water to remove the majority of the PFAS to well below the threshold of 70 parts-per-trillion, as established by the U.S. Environmental Protection Agency. Successful completion of the proposed research will develop the chemical pathways and basic understanding to create high-performing membranes to remove PFAS from water, ultimately with the goal of protecting public health. Additional benefits to society will be accomplished through education and training including the mentoring of two graduate students at Rice University.Per- and polyfluoroalkyl substances (PFAS) are molecules generally composed of 1) an anionic head group, carboxylate or sulfonate; and 2) a fluorinated backbone, which are incredibly resistant to environmental degradation. Their chemical and thermal stability made them ideal substances to use to protect materials from degrading or from events such as fires. Enormous quantities of FPAS were produced until health-related effects initiated the ban of certain species around the turn of the century. However, the large quantity that was produced coupled with their environmental persistence has resulted in widespread contamination of the environment, especially drinking water sources. Documented health risks posed by PFAS to humans include severe malformations in pregnant women, cancer in adults, liver malfunction, thyroid disease, decreased fertility, high cholesterol, and obesity. Given that PFAS have weak affinity and binding towards most chemical adsorbents, the challenge ahead is to design membranes capable of removing them from contaminated water. The overarching goal of this project is to design recognition sites for anionic PFAS, which will be later developed and incorporated into membranes used to filter water that would sequester long- and short-chain PFAS. To accomplish this central objective, the project will 1) design recognition sites embedded within supramolecular scaffolds; 2) synthesize, characterize, and determine the anion binding properties of the most promising scaffolds; and 3) polymerize the most promising architectures via olefinic and/or epoxide functional groups incorporated into the supramolecular scaffold, and test their PFAS sequestration properties in aqueous samples. The successful completion of this project will establish the fundamental parameters to enhance PFAS binding within molecular scaffolds to later translate this knowledge into the design of polymeric filtration materials. Education and outreach activities include creating seminars and hands-on workshops for high school and undergraduate students.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.