CAREER: Stereochemical Biomimicry for Sustainability

This Faculty Early Career Development (CAREER) award addresses a pressing issue in construction materials technology, namely the design of durable cementitious materials with low defect sensitivity and high long-term structural integrity. The functionality and resiliency of our built environment heavily depend on the performance of concrete, a widely adopted material in practical applications. However, the high population of microstructural defects in concrete and the environment's catalytic factors diminish the effectiveness of existing technologies against crack nucleation and growth. Thus, concrete structures' durability and longevity are continuously challenged. This project will enable stereochemical biomimicry pathways through which robust organic-inorganic nano additives and cementitious composites are created. Inspired by nature, this research will couple short-chain organic molecules with an inorganic calcium-silicate-hydrate (C-S-H) to reduce the disparity between concrete's tensile and compressive strength, achieve superior toughness, and decrease inherent porosity and material permeability. In partnership with chemical, biomolecular and computational materials scientists, this research resorts to state-of-the-art experimental methods to discover new synthesis processes of hybrid materials with enhanced or novel physical and chemical properties and to promote progress in engineering science. Inclusive science communication and evidence-based outreach activities will engage an audience of all ages, from K-12 students and undergraduates to U.S. Veterans, especially belonging to historically disadvantaged groups, to prepare them to participate in a future STEM workforce capable of meeting emerging technological challenges. It is established that living organisms use organic molecules and stereochemical recognition to fabricate complex materials characterized by robust physicochemical and mechanical properties. Inspired by this process, the overreaching goal of this research is to unravel the stereochemical biomimicry principles that govern interactions between short-chain functionalized organic molecules and C-S-H. The combined computational and experimental approach will test the following central hypothesis: the interfacial stereochemical effects dictate the nanoparticle nucleation, growth, and self-assembly path in reactive colloidal cement systems. Thus, this award addresses knowledge gaps in three areas: (a) the resolution of stereostructural and energetic binding motifs between the C-S-H and organic molecules; (b) understanding the molecular-scale mechanism, thermodynamic, and kinetic control variables regulating C-S-H nucleation, growth, and texture stabilization in relation to the molecular architecture of the organic modifier; and (c) discovery of stereochemical pathways of C-S-H self-assembly in confined cement environment. Resolving these knowledge gaps will allow the rational design of modifiers for targeted interaction with C-S-H, and engineering biomimetics concrete with reduced defect sensitivity, thus enhancing toughness and long-term structural integrity. This project will enable the PI to advance the knowledge base in materials science, colloids physics and chemistry and to establish his long-term career in engineering biomimetic of infrastructure materials. 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.