Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Towards sustainable materials from biological matter: leveraging macromolecular composition, bonding motifs and hierarchical structure to tailor mechanical performance

Abstract: Addressing the urgent environmental challenges arising from non-degradable plastics and the substantial greenhouse gas emissions linked to conventional infrastructure materials is imperative. Recent studies propose a paradigm shift towards harnessing whole biological matter, or biomatter, as a foundational resource for sustainable materials. The rich macromolecular composition, diverse bonding motifs, and hierarchical arrangement of components within biomatter serve as key factors in tailoring the performance of biomatter-based materials. In this presentation, we will discuss our recent work on transforming photosynthetic algal biomatter into bioplastics which have mechanical properties and processability akin to commodity plastics. Changes in micromorphology, molecular conformation, and bonding patterns within the biomatter are identified as controlling factors for the mechanical properties of the resultant bioplastics. Additionally, composite approaches further aid in modulating these mechanical properties. The holistic evaluation of our algal bioplastics includes also end-of-life considerations, encompassing recycling and biodegradation pathways. On the front of infrastructure materials, we will share our findings on integrating carbon-negative biomatter into cement, aiming to develop hybrid structural materials with a reduced carbon footprint. Particular emphasis is placed on understanding the effects of macromolecular composition on the hydration reactions of cement, as these govern the development of strength in cementitious materials. Leveraging our results as a training dataset, we utilize a closed-loop optimization algorithm that considers material composition, manufacturing conditions, mechanical performance, and life-cycle assessment outputs, specifically CO2 emissions, to drive a holistic design approach for sustainable infrastructure materials.

Bio: Eleftheria Roumeli is an Assistant Professor in the Materials Science & Engineering department of the University of Washington (UW). She is also adjunct Faculty in the Mechanical Engineering Department, Human Centered Design Department and a member of the Molecular Engineering and Sciences Institute, and the Clean Energy Institute at the UW. With a focus on developing and understanding sustainable materials, her research group explores new families of bioplastics, biocomposites and green structural materials derived from biological building blocks, and specifically from biopolymers. Prior to joining UW, Eleftheria completed her postdoctoral work at the California Institute of Technology (2017-2020) and ETH Zurich (2015-2017). She earned her B.S. (2009) and Ph.D. in Physics (2014) from the Aristotle University of Thessaloniki in Greece, where her research focused on understanding the structure-property relationships in polymer nanocomposite materials.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.