CAREER: Stereochemical Biomimicry for Sustainability

该学院早期职业发展(CALEAR)奖致力于解决建筑材料技术中的一个紧迫问题，即设计具有低缺陷敏感度和高长期结构完整性的耐久胶凝材料。我们建筑环境的功能和弹性在很大程度上取决于混凝土的性能，混凝土是一种在实际应用中被广泛采用的材料。然而，混凝土中大量的微结构缺陷和环境的催化因素削弱了现有技术防止裂缝形核和扩展的有效性。因此，混凝土结构的耐久性和寿命不断受到挑战。该项目将实现立体化学生物仿生，通过这些途径可以创造出坚固的有机-无机纳米添加剂和胶凝复合材料。受大自然的启发，本研究将短链有机分子与无机硅酸钙(C-S-H)偶联，以缩小混凝土抗拉强度和抗压强度之间的差距，获得优异的韧性，并降低固有孔隙率和材料渗透性。这项研究与化学、生物分子和计算材料科学家合作，借助最先进的实验方法，发现具有增强或新颖物理化学性质的杂化材料的新合成工艺，并促进工程科学的进步。包容性科学交流和循证外展活动将吸引所有年龄段的受众，从K-12学生和本科生到美国退伍军人，特别是属于历史上处于不利地位的群体，为他们参与未来能够应对新出现的技术挑战的STEM劳动力做好准备。受这一过程的启发，这项研究的超常目标是解开支配短链官能化有机分子与C-S-H相互作用的立体化学生物仿生原理。计算和实验相结合的方法将检验以下中心假设：界面立体化学效应决定了活性胶体水泥系统中纳米颗粒的成核、生长和自组装路径。因此，该奖项涉及三个领域的知识空白：(A)解决C-S-H与有机分子之间的立体结构和能量结合基序；(B)了解与有机修饰剂的分子结构相关的调控C-S-H成核、生长和织构稳定的分子尺度机制、热力学和动力学控制变量；以及(C)发现C-S-H在受限水泥环境中自组装的立体化学途径。解决这些知识差距将允许合理设计与C-S-H有针对性地相互作用的改性剂，并降低缺陷敏感性的工程仿生混凝土，从而增强韧性和长期结构完整性。该项目将使PI能够推进材料科学、胶体物理和化学方面的知识基础，并建立他在基础设施材料工程仿生方面的长期职业生涯。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。

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.