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

University Of Washington, Seattle WA

Investigators

Abstract

NON-TECHNICAL SUMMARY Plastics 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 SUMMARY In 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.