Materials World Network: Liquid Precursor Formation and Crystallization at Interfaces: Fundamentals Towards Applications

一个材料世界网络（MWN）团队已经成立，研究聚合物诱导液体前驱体（PILP）结晶过程的基本方面。该团队的两名研究人员（Gower和Colfen）已经对无机和有机材料的这一过程进行了研究，并有可能为先进材料提供新的仿生加工策略。该工艺的一些潜在应用包括“仿生骨”的开发，可生物降解微胶囊的控释，以及其他需要对敏感生物成分进行良性处理条件的生物材料应用。美国团队由佛罗里达大学材料科学与工程副教授Laurie Gower领导，他的仿生材料化学研究项目以非经典的PILP结晶过程为中心，这是这个美国-德国网络的重点。PILP过程似乎是广泛适用的，其中初步研究发现它可以在多种无机材料中诱导，以及氨基酸的有机晶体。虽然现在已经在许多不同的实验条件下观察到PILP相的形成，但这种不寻常相的基本物理化学性质、稳定性和转化机制在很大程度上仍未得到解决，这将是本项目的重点。德国团队由Dirk Volkmer（乌尔姆大学）和Helmut Colfen（马克斯普朗克胶体和界面研究所）组成。Volkmer的团队已经制备了新型的两亲体和聚合物刷作为矿物沉积的模板，并因其对Langmuir单层下碳酸钙晶体生长的机理研究而得到广泛认可。Colfen的团队因其对非经典结晶过程的研究而得到广泛认可，并对PILP系统的研究做出了开创性的贡献，证明了有机PILP也可以形成。两个实验室都有独特的分析能力来检查这种不寻常的结晶过程的热力学和界面现象。MWN项目由三个重点组成，以三位主要研究人员的主要专业知识为中心。第一个推力检查了基本的热力学和动力学的PILP形成，使用微量热法，超离心，和原位化学滴定；和三元相图将首先确定为更简单的有机PILP系统，将晶格能量参数与形成PILP相的能力相关联。第二个推力开发了一种捕获和稳定不稳定的PILP相的技术，这是确定这种不寻常相的流变特性和光谱分析所必需的。合作研究者Roger Tran-Son-Tay（佛罗里达大学机械工程教授）将提供微流变学仪器和专业知识，用于检测捕获的PILP相的流体特性和凝固动力学；Joanna Long（分子和细胞生物化学副教授）将提供核磁共振专业知识，用于检测积累前体相中的分子相互作用，以及用于检测固化动力学的弛豫时间实验。第三个重点研究了具有明确表面化学和结构的朗缪尔单层膜以及固定化自组装单层膜对前驱体相变的影响。这种界面方面对于稳定伪晶转变以及调节晶体学性质（相、取向、织构和形态）非常重要。这个材料世界网络包括研究生和本科生的培训，特别受益于国际环境中研究和培训的整合。在后一种情况下，材料化学项目将向各自机构的本科生发布广告，并选择排名靠前的学生在他们大三的夏天参加该项目，促进下一代材料科学家之间的国际交流。该奖项与国际科学与工程办公室共同资助。

A Materials World Network (MWN) team has been established which investigates the fundamental aspects of a polymer-induced liquid-precursor (PILP) crystallization process. This process has been examined by two of the investigators of the team (Gower and Colfen), for both inorganic and organic materials, and has the potential to provide new biomimetic processing strategies for advanced materials. Some potential applications of this process include the development of "biomimetic bone", biodegradable microcapsules for controlled release, and other biomaterial applications requiring benign processing conditions for sensitive biocomponents. The US team is led by Laurie Gower, Associate Professor of Materials Science and Engineering (University of Florida), whose research program in biomimetic materials chemistry, is centered around the non-classical PILP crystallization process that is the focus of this US-German network. The PILP process appears to be broadly applicable, in which preliminary studies find that it can be induced in a variety of inorganic materials, as well as organic crystals of amino acids. Although formation of PILP phases has now been observed under many different experimental conditions- the fundamental physicochemical properties, and the stability and transformation mechanisms of this unusual phase are largely unresolved and will be the focus of this project. The German team consists of Dirk Volkmer (University of Ulm) and Helmut Colfen (Max Planck Institute of Colloids and Interfaces). Volkmer's group has prepared novel amphiphiles and polymer brushes as templates for mineral deposition, and is well recognized for their mechanistic studies on the growth of calcium carbonate crystals beneath Langmuir monolayers. Colfen's group is well recognized for their studies of non-classical crystallization processes, and have made seminal contributions to the study of PILP systems, demonstrating that organic PILPs can also be formed. Both labs have unique analytical capabilities for examining the thermodynamics and interfacial phenomena of this unusual crystallization process. The MWN project consists of three thrusts, centered around the primary expertise of the three principal investigators. The first thrust examines the fundamental thermodynamics and kinetics of PILP formation, using microcalorimetry, ultracentrifugation, and in situ chemical titrations; and ternary phase diagrams will first be determined for the simpler organic PILP systems, to correlate lattice energy parameters with the capability of forming PILP phases. The second thrust develops a technique for capturing and stabilizing the labile PILP phase, which is needed for determination of the rheological properties and spectroscopic analysis of this unusual phase. Co-investigators, Roger Tran-Son-Tay (Professor of Mechanical Engineering, U. of Florida), will provide the micro-rheological instruments and expertise for examining the fluidic character and solidification kinetics of the captured PILP phase; and Joanna Long (Associate Professor of Molecular and Cellular Biochemistry) will provide NMR expertise for examining molecular interactions within the accumulated precursor phase, and relaxation time experiments to examine the solidification kinetics. The third thrust examines the influence of Langmuir monolayers, as well as immobilized self-assembled monolayers, with well-defined surface chemistries and structure, on the transformation of the precursor phase. This interfacial aspect is important for stabilizing the pseudomorphic transformation, as well as regulating crystallographic properties (phase, orientation, texture, and morphology). This Materials World Network encompasses training for both graduate and undergraduate level students, with particular benefits from the integration of research and training in an international environment. In the latter case, materials chemistry projects will be advertised to the undergraduate students of the respective institutions, and top ranked students will be selected to participate in the program during the summer of their junior year, facilitating international networking between the next generation of Materials Scientists. This award is co-funded with the Office of International Science and Engineering.