Biomimetic Integration of Organic and Inorganic Phases into Composite Materials

来自加州大学圣巴巴拉分校的一组研究人员与杜邦公司的研究人员合作，提出开发一种方法来定义无机/有机复合材料的图案，以控制形状、强度和热输运。所寻求的仿生模式既包括有机相和无机相之间的空间关系，也包括由此产生的宏观结构的长期层次顺序。一种已知的制造具有明确图案的复合材料的方法是有机表面活性剂和分子无机物质协同组装成介观复合材料。在这种合成中，最终产物的图案是由无机/有机界面控制的。提出的研究将解决聚合物-表面活性剂组合和聚合无机相的使用，以创建具有更长长度尺度的图案的材料。将特别强调使用廉价的碳酸钙或硫酸钙作为无机相。海贝壳是由碳酸钙和1-2%的有机材料组成的，其优异的抗断裂性能表明，即使是本来就很脆的无机材料也可以用来形成坚韧的复合材料。壳韧性的主要决定因素之一是板状文石晶体在有机基质中的长程图案。我们将研究红鲍鱼控制这种结构形成的过程，以了解这种复杂、坚韧的复合材料是如何合成的，并将从生物合成系统中获得的知识应用于复合材料的合成。在生物系统中，微米尺度上的图案被认为是受模板有机物种的控制，而更长的长度尺度上的图案被认为是由于反应扩散机制。这项研究将通过非线性动态反应，包括时钟反应和反应扩散反应，通过调整适当固体材料生长的条件来解决复合图案问题。这些研究的结果将为控制无机/有机复合材料的三维性能提供方法，通过定义无机和有机相在明确的长度尺度上的图案。自然界的一项成就还没有被人类所模仿，那就是同时合成和塑造人造物体。蜘蛛和蚕在吐丝时合成丝；软体动物直接在所需的结构中制备碳酸钙。本提案中描述的研究利用无机/有机界面和非平衡化学探索了有机相和无机相集成到图案复合材料中的方法。杜邦中央研发中心几十年来发展的一流聚合物科学技术将与加州大学圣巴巴拉分校的学术生物和材料科学能力相结合，为学生的培训和研究的执行提供一个工业化的高科技环境。在这些研究中，利用体内生物学研究来指导体外仿生化学的发展。仿生学方法被解释为远远超出了视觉相似性或表面的二维涂层，而是从组成、层次结构和纳米相空间性质的三维、远程图案控制的角度来看待。为实现这一目标，将对复合材料组装的有机与无机协同控制、无机物组织的聚合物结构方向以及时空非平衡合成进行研究。上面概述的方法，在分子水平上理解生物材料通常是精心设计和高度远距离有序组装的背景下，将导致在严格定义的长度尺度上具有特定特性的技术上有用的材料的实际设计。

Abstract DMR-9634396 Stucky A team of investigators from University of California, Santa Barbara, in collaboration with researchers at DuPont, propose to develop methods for defining patterning in inorganic/organic composite materials in order to control shape, strength, and thermal transport. The biomimetic patterning that is sought includes both the spatial relationships between the organic and inorganic phases and the long-range hierarchical ordering of the resulting macrostructures. A known method of creating composite materials with well defined patterning is the cooperative assembly of organic surfactants and molecular inorganic species into mesocomposites. In this synthesis, the patterning in the final product is under control of the inorganic/organic interface. The proposed research will address the use of polymer-surfactant assemblies and polymerized inorganic phases to create materials with patterning on longer length scales. Particular emphasis will be placed on using inexpensive calcium carbonate or calcium sulfate as the inorganic phase. The exceptional fracture resistance of sea shells, which are a composite of calcium carbonate and only 1-2% organic material, demonstrates that even inorganic materials that are inherently brittle can be used to form tough composite materials. One of the major determinants of the toughness of shells is the long-range pattering of tabular aragonite crystals in an organic matrix. The process by which the red abalone controls the formation of this structure will be investigated to understand how this complex, tough composite material is synthesized, and knowledge obtained from the biosynthetic system will be applied to the synthesis of composite materials. While patterning on the micrometer length scale in biological systems is thought to be under control of the templating organic species, patterning on longer length scales is believed to be due to a reaction-diffusion mechanism. This research will address composite patterning by nonlinear dynamic reactions, including clock reactions and reaction-diffusion reactions, by tailoring the conditions to the growth of appropriate solid materials. The results of these studies will provide methods for controlling the three-dimensional properties of inorganic/organic composite materials by defining the patterning of the inorganic and organic phases over well defined length scales. %%% One of the accomplishments of nature that has not been emulated by man is the simultaneous synthesis and shaping of constructed objects. The spider and silkworm synthesize silk as they spin it; the molluscs prepare calcium carbonate directly in the desired architecture. The research described in this proposal explores the integration of organic and inorganic phases into patterned composite materials using inorganic/organic interfaces and non-equilibrium chemistry. The premier polymer science and technology which has been developed over many decades at DuPont Central Research and Development will be combined with the academic bio and materials science capabilities at the University of California, Santa Barbara, to provide an industrial, high technology environment for the training of students and execution of the research. In these studies, in vivo biological studies are used to guide the development of the in vitro biomimetic chemistry. The biomimetics approach is interpreted as being well beyond visual similarities or the two-dimensional coating of surfaces, but is viewed in terms of the three- dimensional, long range patterned control of composition, hierarchical structure and nanophase space properties. Organic and inorganic cooperative control of composite assembly, polymer structure direction of patterned inorganic organization, and space time nonequilibrium syntheses will be investigated to achieve this goal. The approaches outlined above, taken in the context of a molecular level understanding of the often elaborate and highly long range ordered assembly of biomateria ls, will lead to the practical design of technologically useful materials with specific properties over sharply defined length scales.