Toward Soft Diamond: Molecular Modeling for the Engineering of Novel Super-tough Materials

迈向软金刚石：新型超韧材料工程的分子建模

• 批准号: 1435852
• 负责人: Fernando Escobedo
• 金额: $ 28.51万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1435852&HistoricalAwards=false
• 关键词: Toward; Soft; Diamond; Molecular; Modeling

Materials where molecular building blocks are purposely connected in very regular three-dimensional networks are the object of increasing interest. This interest stems in part from the ability to synthesize such materials via self-assembly methods. Depending on the building block used, widely varied materials could be synthesized. At one extreme, a single carbon atom as building block leads to diamond, the hardest materials found in nature. At the other extreme, a very long hydrocarbon chain as building block leads to very soft plastics. In between, building blocks of intermediate size and stiffness would lead to exciting new materials that combine some of the strength of diamond with the elasticity of rubbers. Our preliminary studies have revealed that networks made of two types of building blocks that differ in stiffness or chemical affinity would form rubbers that mimic the elastic response of super-tough natural materials such as the adhesive in abalone shells and spiders' silk. This study is complementary to experimental efforts by other groups. It will fill a gap in the need for computational models that help identify specific material configurations of interest. The research will hence provide guidelines for the design of super-tough "rubbery diamonds" that could become a new materials' paradigm. In the long term, this could impact a broad range of materials related industries. The work will also provide opportunities for the involvement of underrepresented groups in research and the development of educational materials. Since the resistance to deformation in an elastomer composed of ordered and amorphous domains is associated with the free energy cost of rearranging those domains, it is postulated that the elastic properties of regular networks can be optimized by using building blocks that allow control of the free-energy barriers of the underlying order-disorder phase transitions (driven by deformation). Accordingly, the plan is to synergistically leverage the self-assembling properties of chains that are capable of forming entropy-driven liquid crystalline order (like semiflexible chains) and enthalpy-driven micro-segregated ordered phases (like block copolymers) to tune the non-linear elastic behavior of end-chain crosslinked networks with no or minimal defects. The aim is to modulate the height and number of free-energy barriers associated with a sawtooth elastic response. Molecular dynamics simulations will be used to investigate the effects on elastic behavior of different block copolymers (whose blocks differ in either enthalpic affinity or backbone flexibility) and of non-ideal architectures and defects.

分子构建块故意连接在非常规定的三维网络中的材料是增加兴趣的对象。 这种兴趣部分源于通过自组装方法合成此类材料的能力。根据所使用的构建块，可以合成各种多样的材料。在一个极端，单个碳原子作为构建块导致钻石，这是自然界中最难的材料。在另一个极端情况下，作为基础块很长的碳氢化合物链会导致非常柔软的塑料。在两者之间，中等大小和刚度的构件将导致令人兴奋的新材料，这些材料将钻石的某些强度与橡胶的弹性结合在一起。我们的初步研究表明，由两种类型的构件组成的网络在刚度或化学亲和力方面有所不同，会形成橡胶，从而模仿超高型天然材料的弹性响应，例如鲍鱼壳和蜘蛛丝的粘合剂。这项研究与其他群体的实验努力互补。它将填补对有助于识别特定材料感兴趣的特定材料配置的计算模型的空白。因此，这项研究将为可能成为新材料的范式的超距离“橡胶钻石”的设计提供指南。从长远来看，这可能会影响广泛的材料相关行业。这项工作还将为人数不足的群体参与研究和教育材料的发展提供机会。由于由有序和无定形结构域组成的弹性体中对变形的阻力与重新排列这些结构域的自由能成本有关，因此可以通过使用允许自由控制的构建块来优化常规网络的弹性特性基础阶阶相变（由变形驱动）的能屏障。因此，该计划是协同利用能够形成熵驱动的液体晶体秩序（如半串联链）和焓驱动的微分离有序相（如块共聚物）来调整非 - 非 - 端链交联网络的线性弹性行为，没有或最小缺陷。目的是调节与锯齿弹性响应相关的自由化屏障的高度和数量。分子动力学模拟将用于研究对不同块共聚物的弹性行为的影响（其嵌段性亲和力或骨架柔韧性的块有所不同）以及非理想的结构和缺陷。