Biomimetic Routes to Crystals with Superior Mechanical Properties

大自然能够显著控制矿物生长，产生生物矿物，如骨骼、牙齿和贝壳，它们经常显示出不寻常的形态和上级机械性能。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。生物矿物通常是复合材料，包含少量与矿物组分结合的有机材料，并且正是这与它们的结构组织一起导致上级的机械性能。许多生物矿物是无定形或多晶的，这是相对容易解释为什么这些结构具有良好的机械性能。然而，特别值得注意的是生物单晶，其也可以显示出相当大的抗断裂性，通常认为这种行为来自于晶体内封闭的有机大分子。这与合成单晶不同，合成单晶由于存在低能量断裂面，通常很容易断裂。本提案将研究在晶体中加入添加剂以提高其机械性能，目的是生产各种具有改善的抗断裂性的晶体，并了解如何将这些添加剂加入单晶中。虽然有机添加剂的掺入非常适合于在环境条件下形成和使用的生物矿物，但它不能应用于在合成和使用期间通常暴露于更极端条件的先进材料。该项目为这一问题提供了一种新的解决方案，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。将这些复合晶体的机械性能与结合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策略进行系统和定量研究。

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.