EFRI E3P: Tuning Catalyst Design to Recycle Mixed Polymer Streams

该项目旨在开发一种新的方法来升级和回收多层聚合物薄膜。多层膜通常表现更好，在包装等应用中需要的塑料材料更少，但其复杂性使其回收比其他简单形式的塑料（如硬质瓶）更具挑战性。该项目的研究人员旨在开发选择性靶向和转化多层膜组分的催化剂，允许使用常规方法回收剩余的聚合物。这种催化靶向将通过改性几种有前途的催化剂载体的表面并在其表面上引入活性位点以允许选择性靶向和转化感兴趣的聚合物或杂质来实现。三个系列的催化剂将根据其目标和转化感兴趣的组分的有效性，易于从多层聚合物混合物中分离，并有效地重复使用进行评估。将建立一个模型，以确定每种方法的成本效益，重新集中努力的家庭催化剂，表现出最大的潜力，以经济地回收多层膜。在进行科学和工程研究的同时，还将进行公众看法调查和教育干预，目的是向公众宣传这一问题的重要性，从而提高公众的认识、接受和参与。最终，该提案将为更先进的多层塑料的成本效益回收奠定基础。这将理想地实现多层塑料所具有的技术优势，例如更长的食品保质期，而不会牺牲有效回收所涉及塑料的能力。由于多层薄膜通常由非常不同的聚合物组合组成，以及微量的连接层，它们与专注于特定化学物质的传统回收技术不兼容。其转化的常用方法是使用昂贵的溶剂基方法进行分层或溶解-沉淀，当存在多个流时，该方法容易变得成本过高。该提案旨在开发一组针对这些多组分膜中的特定聚合物家族的催化颗粒，使得非极性残留物可以容易地再循环。极性聚合物将通过操纵三种催化剂家族（碳纳米管、二氧化硅颗粒和沸石）上的外部官能团来选择性地靶向。这些家族的选择是基于它们引入表面官能团的容易性、靶向熔融聚合物的有效性、极性组分转化后的回收和再生。该团队将进一步测试这一假设，即微量添加的水可以通过远程极化和质子化来远程激活一些极性分子，进一步扩展这些混合物中极性分子的激活速率和选择性。由此产生的动力学数据将被纳入一个技术经济模型，比较这种方法与溶剂为基础的方法。研究的这一技术部分将与公众看法调查同时进行，以指导改进关于这一问题重要性的公众教育，并将这一信息纳入小组的外联工作。此外，还将开展面向初中生和高中生的拓展活动，同时为化学工程和心理学等不同领域的本科生和研究生创造研究机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to develop a new approach to upgrade and recycle multilayer polymer films. Multilayer films generally perform better and require much less plastic material in applications such as packaging, but their complexity makes them far more challenging to recycle than other simpler forms of plastic like rigid bottles. The investigators in this project aim to develop catalysts that selectively target and convert components of the multilayer films, allowing the remaining polymer to be recycled using conventional methods. This catalytic targeting will be accomplished by modifying the surface of several promising catalyst supports and incorporating active sites on their surface to allow selective targeting and conversion of polymers or impurities of interest. Three families of catalysts will be evaluated based on their effectiveness for targeting and converting the components of interest, ease of separation from the multilayer polymer mixture, and effective re-use. A model will be constructed to determine the cost-effectiveness of each approach to refocus efforts on families of catalysts that exhibit the greatest potential for economically recycling multilayer films. The scientific and engineering research will be accompanied by public perception surveys and education interventions aimed at communicating the importance of this problem to the general public and thereby increasing public awareness, acceptance, and participation. Ultimately, this proposal will lay the groundwork for the cost-effective recycling of more advanced multilayered plastics. This will ideally enable the technological advantages that accompany multilayer plastics such as longer food shelf lives without sacrificing the ability to effectively recycle the plastics involved.Because multilayer films typically consist of very diverse sets of polymers, as well as trace amounts of tie layers, they are not compatible with traditional recycling technologies focused on a specific chemistry. Common approaches for their conversion are delamination or dissolution-precipitation using costly solvent-based processes that can easily become cost prohibitive when multiple streams are present. This proposal aims to develop a set of catalytic particles that target specific families of polymers in these multi-component films such that the nonpolar residue can be readily recycled. Polar polymers will be selectively targeted by manipulating external functional groups on three families of catalysts - carbon nanotubes, silica particles, and zeolites. These families are chosen based on their ease of introducing surface functionalities, effectiveness in targeting molten polymers, recovery, and regeneration after conversion of polar components. The team will further test the hypothesis that trace amounts of added water can serve to remotely activate some polar molecules through remote polarization and protonation, further extending the rates and selectivity activation of polar molecules in these blends. Resulting kinetic data will be incorporated into a techno-economic model to compare this approach with solvent-based approaches. This technical component of the research will be carried out in parallel with public perception surveys to guide improved public education regarding the importance of this problem, with this information being incorporated into the team’s outreach efforts. Outreach activities involving middle and high school students will be developed, while also creating research opportunities for undergraduate and graduate students spanning the diverse fields of Chemical Engineering and Psychology.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.