CAS: Molecular Engineering of Efficient Compatibilizers in Polymer Recycling

塑料是广泛的社会领域的关键材料，包括医疗保健、食品储存、包装和运输等。然而，必须改进对报废塑料的管理，因为目前大多数材料的生命周期都在垃圾填埋场或焚化炉结束。因此，迫切需要开发技术来管理废旧塑料的环境和经济后果。不幸的是，与处置竞争的选择有限。机械回收是目前最常见的技术，但需要分离混合废物流以提供纯聚合物，因为大多数聚合物对产生不明确的混合物，性能较差。新型高效聚合物表面活性剂的开发可以改善聚合物回收中普遍存在的混合塑料废物流的性能。因此，该研究计划将为开发新型聚合物改性剂提供基础，以提高当前聚合物的回收利用。值得注意的是，这些结果使材料的开发具有近期效益，可以有效地回收目前环境中的塑料。因此，这些分子设计原理的识别在新兴的化学回收、新材料设计努力和当前机械回收塑料技术之间提供了一座桥梁。劳动力的发展和下一代科学家和工程师的培训，他们准备应对减轻塑料寿命结束对经济，环境和社会影响的重大挑战，将通过这项研究计划以及让公立高中学生参与实践研究经验来实现。此外，将建立一个以可持续材料为重点的课程模块的网上交流中心，并向公众提供。技术概述本研究计划的总体目标是为设计混合塑料废物流的最佳聚合物增容剂提供基础。由于晶体聚合物在聚合物回收中占主导地位，研究工作将为相分离晶体聚合物共混物的有效增容剂的分子设计特性提供基础信息。最初的实验将寻求确定关键的分子特征，使相容剂和均聚物在相分离的结晶聚合物共混物中共结晶，从而加强弱界面。这些研究将与在聚合物的化学回收中拦截远旋中间体的努力相结合，这些中间体可能用作增值材料，例如它们用作合成多嵌段共聚物的原料，以兼容聚合物废物流衍生的相分离共混物。这些最佳增容剂的目标分子特性将通过上述分子设计工作获得。将研究这些构建块在被动和反应处理方案中形成最佳相容剂的功效，目的是提供联合利用化学和机械回收的途径，从废弃塑料中开发改进材料。该研究项目的这一部分将对环境产生更大的影响，因为它连接并改善了聚合物的化学和机械回收。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。

NON-TECHNICAL SUMMARYPlastics are critical materials for broad swaths of society, including healthcare, food storage, packaging, and transportation, among others. However, managing end-of-life plastics must be improved, as the life-cycle of most materials currently end in landfills or an incinerator. Therefore, there is an urgent need to develop technologies to manage the environmental and economic consequences of end-of-life plastics. Unfortunately, the options available to compete with disposal are limited. Mechanical recycling is the most common current technology, but requires separation of a mixed waste stream to provide pure polymer as most polymer pairs produce ill-defined mixtures with inferior properties. The development of novel and effective polymeric surfactants can improve the properties of mixed plastic waste streams that are ubiquitous in polymer recycling. This research program will therefore provide a foundation to develop novel polymeric modifiers that are required to enhance current polymeric recycling. Notably, these results enable the development of materials that will have near-term benefits allowing the efficient reclamation of plastics currently in the environment. As such, the identification of these molecular design principles provides a bridge between emerging chemical recycling, new materials design efforts, and current technologies to mechanically recycle plastics. Workforce development and training of the next generation of scientists and engineers who are prepared to tackle the grand challenges in mitigating the economic, environmental and societal effects of the end of life of plastics will be realized through this research program and also by engaging public high school students in hands-on research experiences. Additionally, an online clearinghouse for curriculum modules focused on sustainable materials will be established and made available to the public.TECHNICAL SUMMARYThe overarching goal of this research program is to provide a foundation from which optimal polymeric compatibilizers for mixed plastic waste streams may be designed. As crystalline polymers dominate polymer recycling, research efforts will provide fundamental information that delivers molecular design characteristics for effective compatibilizers of phase separated crystalline polymer blends. Initial experiments will seek to identify crucial molecular characteristics that enable the co-crystallization of compatibilizers and homopolymers in phase separated crystalline polymer blends, thereby strengthening weak interfaces. These studies will be coupled with efforts to intercept telechelic intermediaries in the chemical recycling of polymers that may be used as value-added materials, such as their use as feedstocks to synthesize multiblock copolymers that compatibilize polymer waste stream-derived phase separated blends. The targeted molecular characteristics of these optimal compatibilizers will be informed by the molecular design efforts described above. The efficacy of these building blocks to form optimal compatibilizers in both passive and reactive processing schemes will be studied, with the goal of providing routes to jointly utilize chemical and mechanical recycling in developing improved materials from end-of-life plastics. This portion of the research program will therefore have an amplified environmental impact as it links and improves both chemical and mechanical recycling of polymers..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.