EFRI E3P: Tuning Catalyst Design to Recycle Mixed Polymer Streams

本项目旨在开发一种多层聚合物薄膜升级和回收的新方法。多层薄膜通常性能更好，在包装等应用中需要的塑料材料也少得多，但它们的复杂性使它们比其他简单形式的塑料（如刚性瓶）更难回收。该项目的研究人员旨在开发催化剂，选择性地靶向并转化多层膜的成分，使剩余的聚合物可以使用传统方法进行回收。这种催化靶向将通过修饰几种有前途的催化剂载体的表面并在其表面加入活性位点来实现，以允许选择性靶向和转化感兴趣的聚合物或杂质。三种催化剂家族将根据其靶向和转化感兴趣成分的有效性，从多层聚合物混合物中分离的便利性以及有效的再利用性进行评估。将建立一个模型来确定每种方法的成本效益，以重新集中精力在具有最大经济回收多层膜潜力的催化剂家族上。在进行科学和工程研究的同时，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，这一建议将为更先进的多层塑料的低成本回收奠定基础。理想情况下，这将使多层塑料带来的技术优势，如更长的食品保质期，而不会牺牲有效回收塑料的能力。由于多层膜通常由非常多样化的聚合物和微量的结层组成，因此它们与传统的专注于特定化学成分的回收技术不兼容。它们转化的常用方法是分层或溶解沉淀，使用昂贵的溶剂型工艺，当存在多个流时，这种方法很容易变得成本过高。本提案旨在开发一套催化颗粒，针对这些多组分薄膜中的特定聚合物家族，使非极性残留物可以很容易地回收。极性聚合物将通过操纵三种催化剂家族的外部官能团——碳纳米管、二氧化硅颗粒和沸石——来选择性地靶向。这些家族的选择是基于它们易于引入表面功能，有效地瞄准熔融聚合物，极性组分转化后的回收和再生。该团队将进一步验证这一假设，即微量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，从而进一步延长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纳入技术经济模型，以比较这种方法与基于溶剂的方法。这项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，并将这些资料纳入小组的外联工作。将发展涉及初高中学生的外展活动，同时也为跨越化学工程和心理学不同领域的本科生和研究生创造研究机会。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。

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.