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

一个材料世界网络(MWN)小组已经成立，该小组研究聚合物诱导液体前体(PILP)结晶过程的基本方面。该团队的两名研究人员(高尔和科尔芬)已经对这一过程进行了检查，包括无机和有机材料，并有可能为先进材料提供新的仿生加工策略。这一工艺的一些潜在应用包括开发“仿生骨”、用于控制释放的可生物降解微胶囊，以及其他需要对敏感生物成分进行良性加工的生物材料应用。美国团队由佛罗里达大学材料科学与工程副教授劳里·高尔领导，他的仿生材料化学研究项目围绕着这个美德网络的重点--非经典的PILP结晶过程。PILP过程似乎具有广泛的适用性，初步研究发现，它可以在各种无机材料以及氨基酸的有机晶体中诱导。虽然现在已经在许多不同的实验条件下观察到了PILP相的形成-这种不寻常的相的基本物理化学性质以及稳定性和转化机制在很大程度上还没有解决，这将是本项目的重点。德国队由德克·沃尔克默(乌尔姆大学)和赫尔穆特·科尔芬(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两亲性和聚合物刷子作为矿物沉积的模板，并因其在朗缪尔单分子膜下生长碳酸钙晶体的机理研究而广为人知。Colfen的团队因其对非经典结晶过程的研究而广为人知，并在PILP体系的研究中做出了开创性的贡献，证明了有机PILP也可以形成。这两个实验室都有独特的分析能力来研究这一不寻常的结晶过程的热力学和界面现象。MWN项目包括三个推力，围绕三个主要调查人员的主要专业知识。第一个推力使用微量热法、超速离心法和原位化学滴定来研究PILP形成的基本热力学和动力学；对于较简单的有机PILP体系，将首先确定三元相图，以将晶格能量参数与PILP相的形成能力关联起来。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性和光谱分析所必需的。共同研究人员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，用于研究捕获的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，用于研究累积前驱物相中的分子相互作用，以及松弛时间实验，以研究凝固动力学。第三个重点考察了具有明确表面化学成分和结构的朗缪尔单分子膜以及固定化自组装单分子膜对前驱体相转变的影响。这种界面方面对于稳定假象转变以及调节晶体性质(相、取向、织构和形态)是重要的。这个材料世界网络包括对研究生和本科生的培训，特别是受益于在国际环境下的研究和培训的整合。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，排名最好的学生将在大三的暑期被选为该项目的参与者，以促进下一代材料科学家之间的国际联系。该奖项是与国际科学与工程办公室共同资助的。

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.