EAGER: CAS: From polymer mixtures to sustainable foams with controlled hierarchical porosity and mechanics

非技术性塑料在社会上发挥着至关重要的作用，但它们对环境的影响，从石油来源到报废处理，引起了重大关切。泡沫塑料的应用尤其面临挑战，因为不可再生和有毒的建筑材料，以及所产生的聚合物泡沫塑料的不可回收和不可降解。目前的可持续泡沫塑料方法涉及重新组装从生物质中提取的有用的聚合物构件。然而，这些方法会导致浪费，并受到可伸缩性限制。该项目引入了从未经加工的可再生原料中获得的聚合物混合物直接合成泡沫塑料的新颖和潜在的变革性概念，从而消除了提取的需要。通过研究聚合物相互作用和发泡机理，可以实现对结构和性能的精确控制。如果成功，该项目将生产出与石油衍生产品类似的可加工性和机械性能的泡沫，同时还提供可降解性和可回收利用的优势，突破真正可持续的聚合物泡沫的界限。所获得的知识将延伸到具有类似分子特征的其他聚合物混合物，扩大其影响范围，超出生物质聚合物混合物的范围。调查结果和方法将纳入材料加工和聚合物科学课程以及公共宣传活动。该项目将对学生进行可持续聚合物科学/工程原理的培训，培养和教育具有环保意识的材料专业人员。技术总结在泡沫塑料应用方面，精确控制传统聚合物的分子组成和层次结构，如聚氨酯和聚苯乙烯，在其在各个行业的广泛应用中发挥了关键作用。然而，一个重大的挑战是，这些广泛使用的聚合物来自不可再生和有毒的单体，并导致泡沫塑料不可回收和不可降解。可持续的替代方案包括从生物质衍生的小分子中合成单体，或者从生物质中提取聚合物并将其重新组装成泡沫。然而，这些方法需要提取过程，导致废物产生和可伸缩性限制，而且它们不一定会产生可降解或可回收的泡沫。为了克服这些挑战，该项目提出了一种新的方法，消除了提取过程的需要，转而利用可再生原料中存在的固有聚合物混合物。其目标是从未经加工的生物质中发现的聚合物混合物中直接制备具有可控结构和力学性能的分层聚合物泡沫。中心假设是，通过利用电荷络合和热机械处理，可以实现对泡沫的分级结构、孔隙率和机械性能的精确控制。丰富的藻类生物量将被用作可再生聚合物原料来验证这一方法。分析将包括评估泡沫结构、孔隙率、孔形态和机械性能，以建立结构-性能关系。此外，还将研究土壤的可回收性和降解性。这项研究的结果将推动可持续的泡沫制造工艺，使可再生聚合物能够生产高性能、可降解和可回收的泡沫。所获得的知识将超越基于生物质的聚合物，有助于更广泛地了解具有类似分子特征的其他聚合物混合物。此外，本提案中调查的材料将被整合到教学、教育和外展活动中。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 play a crucial role in society, but their environmental impacts, from petroleum-based sourcing to end-of-life disposal, raise significant concerns. Foam applications, in particular, present challenges due to non-renewable and toxic building blocks, as well as non-recyclability, and non-degradability of the resulting polymer foams. Current sustainable foam approaches involve reassembling useful polymer building blocks extracted from biomass. Yet, these approaches lead to waste and suffer from scalability limitations. This project introduces the novel and potentially transformative concept of synthesizing foams directly from polymer mixtures obtained from unprocessed renewable feedstocks, thus eliminating the need for extraction. By studying polymer interactions and foaming mechanisms, precise control over structure and properties can be achieved. If successful, this project will produce foams that exhibit similar processability and mechanical properties as petroleum-derived counterparts, while also offering the advantages of degradability and recyclability, pushing the boundaries of truly sustainable polymer foams. The knowledge gained will extend to other polymer mixtures with similar molecular features, expanding the impacts beyond biomass-based polymer mixtures. The findings and methodologies will be integrated into materials processing and polymer science curricula, as well as public outreach activities. The project will train students in sustainable polymer science/engineering principles, fostering and educating environmentally conscious materials professionals. TECHNICAL SUMMARYIn the context of foam applications, achieving precise control over the molecular composition and hierarchical structure in conventional polymers, such as polyurethanes and polystyrenes, has played a pivotal role in their widespread utilization across various industries. However, a significant challenge arises from the fact that these widely used polymers are derived from non-renewable and toxic monomers, and result in foams that are non-recyclable and non-degradable. Sustainable alternatives involve synthesizing monomers from biomass-derived small molecules or extracting polymers from biomass and reassembling them into foams. However, these approaches necessitate extraction processes, leading to waste generation and scalability limitations, and they don’t necessarily lead to degradable or recyclable foams. To overcome these challenges, this project presents a novel approach that eliminates the need for extraction processes and instead utilizes the inherent polymer mixtures present in renewable feedstocks. The objective is to prepare hierarchical polymeric foams with controlled structure and mechanical properties directly from polymer mixtures found in unprocessed biomass. The central hypothesis is that by harnessing charge complexation and thermomechanical processing, precise control over the hierarchical structure, porosity, and mechanical properties of the foams can be achieved. Abundant algal biomass will be used as a renewable polymer feedstock to validate this approach. The analysis will encompass evaluating foam structure, porosity, pore morphology, and mechanical properties, to establish structure-property relationships. Additionally, studies will be conducted on recyclability and degradation in soil. The outcomes of this research will advance sustainable foam manufacturing processes, enabling the production of high-performance, degradable, and recyclable foams from renewable polymers. The knowledge gained will extend beyond biomass-based polymers, contributing to a broader understanding of other polymer mixtures with similar molecular characteristics. Furthermore, the materials investigated in this proposal will be integrated into teaching, education, and outreach activities..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.