Strong and Multifunctional Geopolymer Composites: A Multi-Scale Study

该奖项支持基础研究，以提供新的知识，为先进的地质聚合物复合材料的系统设计铺平道路。地聚合物复合材料是一类新的无定形聚合物杂化材料，具有诱人的特性，有可能极大地改变复合材料的合成方式。基于土聚合物的杂化材料广泛应用于土木、航空航天、机械和生物医学工程等领域。然而，性能、化学和成分之间的既定关系是缺乏的。因此，尽管地聚合物材料具有很高的潜力，但其广泛应用受到了阻碍。尖端实验与先进计算建模的结合将加速发现高性能多功能结构复合材料。土聚合物复合材料已被用于许多跨学科的应用，包括增强性能的建筑材料、建筑的被动冷却系统、用于骨修复的生物材料、用于清洁能源的膜和隔音系统。因此，这项研究的结果将有益于美国的经济和社会，并刺激材料的发现。这项研究涉及三个机构和跨学科的合作，包括纳米科学、固体力学和材料科学。将与当地高中合作开展全面的外联活动，为培养下一代材料科学家做出贡献。因此，这种多学科的方法将有助于扩大未被充分代表的群体在研究中的参与，并对工程教育产生积极影响。地质聚合物是由铝硅酸盐来源与碱金属氢氧化物或硅酸盐溶液反应产生的无定形无机聚合物。尽管进行了大量的研究，但对土聚复合材料强度的来源还没有完全了解。本研究以连续介质和计算微力学为基础，结合纳米尺度的力学表征方法，将微纳成分的有效响应联系起来，以填补这一知识空白。研究小组将建立预测宏观本构行为的理论细观力学模型，使用非线性均匀化理论中的改进割线方法阐明新的变分解，建立考虑多轴加载情况和形态特征的周期性微观场有限元模型，验证纳米孔隙率是控制宏观力学响应的驱动因素的假设，通过对微球增强钾基土聚树脂复合材料进行纳米和宏观力学试验来验证理论模型，并建立纳米和微观尺度特征与宏观行为之间的关联。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，认为值得支持。

This award supports fundamental research to provide new knowledge that paves the way for a systematic design of advanced geopolymer composites. Geopolymer composites are a new class of amorphous polymeric hybrids with attractive attributes that have the potential to drastically change the way composites materials are synthesized. Geopolymer-based hybrids are relevant to a vast array of fields such as civil, aerospace, mechanical, and biomedical engineering. However, established relationships between performance, chemistry, and composition are lacking. As a consequence, the widespread application of geopolymer-based materials has been impeded, despite their high potential. The integration of cutting-edge experiments with advanced computational modeling will accelerate the discovery of high-performance multifunctional structural composites. Geopolymer composites have been theorized for many interdisciplinary applications including enhanced-performance construction materials, passive cooling systems for buildings, biomaterials for bone repair, membranes for clean energy generation, and sound insulation systems. Therefore, results from this research will benefit the U. S. economy and society, and spur materials discovery. This research involves the collaboration between three institutions and across disciplines including nanoscience, solid mechanics, and materials science. Comprehensive outreach activities will be implemented in collaboration with local high schools to contribute to raising the next generation of materials scientists. Therefore, the multi-disciplinary approach will help broaden participation of underrepresented groups in research and positively impact engineering education.Geopolymers are amorphous inorganic polymers that result from the reaction between an aluminosilicate source and an alkali metal hydroxide or silicate solution. Despite a wealth of studies, the origin of the strength of geopolymer composites is not fully understood. This research is to fill the knowledge gap by connecting the effective response to the micro- and nano- constituents based on continuum and computational micromechanics integrated with nanoscale mechanical characterization methods. The research team will formulate a theoretical micromechanics model to predict the macroscopic constitutive behavior, articulate new variational solutions using the modified secant approach within nonlinear homogenization theory, build a periodic microfield finite element model that accounts for multiaxial loading cases as well as morphological features, test the hypothesis that nano-porosity is the driving factor controlling the macroscopic mechanical response, validate the theoretical models by carrying out nano- and macro-scale mechanical tests on microsphere-reinforced potassium-based geopolymer composites, and establish correlations between nano- and micro-scale characteristics and the macroscopic behavior.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.