DMREF: Collaborative Research: Strain Adaptive Materials

非技术描述：软机器人、可穿戴电子设备和个性化医学的出现引发了对模拟生物组织机械反应的合成材料的需求。活组织是独一无二的，因为它们触感柔软，但不会变形。这种应变适应性僵硬代表了大自然的一种防御机制，可以防止意外的组织破裂，并注入一种特有的坚固感。人们探索了各种分子和宏观结构来重现组织力学；然而，它们未能在分子尺度上整合柔韧性和坚固性。该项目旨在开发一个材料设计平台，该平台利用建筑规范来编程机械响应的巨大变化，从超软脑组织到超级坚硬的皮肤。通过软物质理论家、合成化学家和实验物理学家的闭环合作，这种按结构设计的方法将启发合成化学和软物质物理领域的新方向，创造具有编码结构-性质关联的新的分子结构。根据材料基因组倡议的使命，这一方法将构成材料设计搜索引擎的基础，该搜索引擎将指导和加速合成具有目标机械特性的组织复制品。这些新型材料将催化许多技术的根本性转变，包括但不限于软机器人、主动伪装系统和生物医学设备。技术说明：传统的凝胶和弹性体不能复制组织的应变适应性硬化。变形时从超软到超牢固的力学响应需要不同结构母体的层次化组织，从而在不同的应力水平触发一连串的变形机制。因此，该项目将应对三个根本性且日益复杂的挑战。首先，理论建模将在网络结构和机械特性(如刚性和坚固性)之间建立普遍的关联，并将形成在设计的聚合物系统中编码精确的机械“表型”的定量指导方针。其次，在网络结构代码中引入自组装部分将使聚合物组件具有应变自适应加强能力。第三，动态交联剂的引入将提供可编程的粘弹性响应，并将平台扩展到应变率响应性力学表型。项目目标的实现将产生一种分子代码--共同实现具有应变和应变率自适应机械性能的下一代组织状合成材料的可编程和高效开发。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。

Non-technical Description: The advent of soft robotics, wearable electronics, and personalized medicine has sparked a demand for synthetic materials that mimic the mechanical responses of living tissues. Living tissues are unique as they are soft at touch, yet resistant to deformation. This strain-adaptive stiffening represents one of Nature's defense mechanisms that prevents accidental tissue rupture and imbues a characteristic feeling of firmness. Various molecular and macroscopic constructs have been explored to reproduce the tissue mechanics; however, they fail to integrate softness and firmness on a molecular scale. This project aims at the development of a materials design platform that harnesses architectural codes for programming the grand variation of mechanical responses, ranging from that of ultra-soft brain tissue to super-firm skin. Through closed-loop collaboration of soft matter theoreticians, synthetic chemists, and experimental physicists, this design-by-architecture approach will inspire new directions in synthetic chemistry and soft-matter physics towards creation of novel molecular architectures with encoded structure-property correlations. In line with the mission of the Materials Genome Initiative, this approach will constitute the foundation for a materials design search engine that will guide and accelerate the synthesis of tissue replicas with targeted mechanical properties. The novel classes of materials will catalyze fundamental shifts in many technologies, including - but not limited to - soft robotics, active camouflage systems, and biomedical devices. Technical Description: Conventional gels and elastomers cannot replicate tissue's strain-adaptive stiffening. Transition from the super-soft to super-firm mechanical response upon deformation requires a hierarchical organization of different structural motifs that trigger a cascade of deformation mechanisms at different stress levels. As such, the project will address three fundamental and increasingly complex challenges. First, theoretical modeling will establish universal correlations between network architecture and mechanical properties such as stiffness and firmness, and will form quantitative guidelines for encoding precise mechanical "phenotypes" in designed polymeric systems. Second, introduction of self-assembling moieties into network architectural code will empower polymer assemblies with strain-adaptive stiffening. Third, incorporation of dynamic crosslinks will impart programmable viscoelastic response and extend the platform to strain-rate responsive mechanical phenotypes. Fulfillment of the project goals will yield a molecular code - collectively enabling the programmable and efficient development of next-generation of tissue-like synthetic materials with both strain- and strain rate-adaptive mechanical properties.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.