Biomimetic Routes to Crystals with Superior Mechanical Properties

大自然能够显著地控制矿物的生长，产生生物矿物，如骨骼、牙齿和贝壳，它们经常表现出不同寻常的形态和优越的机械性能。显然，这是在温和的条件下实现的，并为新材料的设计和合成提供了独特的灵感。生物矿物是典型的复合材料，由少量的有机材料和矿物成分组成，这与它们的结构组织一起导致了优越的机械性能。许多生物矿物要么是无定形的，要么是多晶的，并且相对容易解释为什么这些结构具有良好的力学性能。然而，特别值得注意的是，生物单晶也可以显示出相当大的抗断裂性，这种行为通常被认为是由晶体内封闭的有机大分子引起的。这与合成单晶相反，由于存在低能断裂面，单晶通常很容易断裂。本提案将研究在晶体中加入添加剂作为增强其机械性能的途径，目的是生产具有提高抗断裂性的广泛晶体，并了解如何将这些添加剂掺入单晶中。虽然有机添加剂的掺入非常适合在环境条件下形成和使用的生物矿物，但它不适用于在合成和使用过程中通常暴露在更极端条件下的高级材料。该项目为这一问题提供了一种新颖的解决方案，并将首次在单晶中加入化学和热稳定的颗粒，以改善其机械性能。这些复合晶体的机械性能将与含有机添加剂的合成晶体和单晶生物矿物进行比较。该项目还将首次对这种生物成因策略进行系统和定量的研究。

Nature is capable of remarkable control over mineral growth, producing biominerals such as bones, teeth and seashells which frequently display unusual morphologies and superior mechanical properties. Clearly this is achieved under mild conditions, and provides a unique inspiration for design and synthesis of new materials. Biominerals are typically composite materials, comprising a small amount of organic material in association with the mineral component, and it is this together with their structural organisation that results in the superior mechanical properties. Many biominerals are either amorphous or polycrystalline, and it is relatively easy to explain why these structures have good mechanical properties. Particularly remarkable, however, are biogenic single crystals which can also show considerable fracture resistance, behaviour which is generally considered to derive from organic macromolecules occluded within the crystals. This is in contrast to synthetic single crystals which typically fracture very easily due to the presence of low-energy fracture planes.This proposal will investigate incorporation of additives within crystals as a route to enhancing their mechanical properties, with the aim of producing a wide range of crystals with improved fracture resistance, and understanding how such additives can be incorporated within a single crystal. Although incorporation of organic additives is well-suited to biominerals which are formed and used under ambient conditions, it cannot be applied to advanced materials which are typically exposed to more extreme conditions during synthesis and use. This project offers a novel solution to this problem, and will for the first time incorporate chemically and thermally stable particles within single crystals to improve their mechanical properties. The mechanical properties of these composite crystals will be compared with both synthetic crystals incorporating organic additives and single crystal biominerals. The project will also provide the first systematic and quantitative study of this biogenic strategy.