GOALI: Crystallization of Organic Glasses

DMR 0907031：有机玻璃的结晶技术摘要：在这个合作项目中，教授。威斯康星大学的连宇、马克·艾迪格和胡安·德·巴勃罗？麦迪逊、雅培实验室的Geoff Zhang博士和他们的研究学生同事将研究有机玻璃的结晶。玻璃杯是太冷而不能流动的液体。根据目前认为析晶受扩散控制的观点，有机玻璃不应轻易析晶。然而，最近的研究表明，许多晶体确实结晶了，有时结晶的速度比标准模型预测的速度快105倍。本研究涉及在玻璃化转变温度附近激活的两种晶体生长模式：体模式和表面模式。这两种增长模式都太快，无法通过整体扩散来控制。该团队将测试这一假设，即如果晶体和液体结构之间存在足够的相似性，玻璃态固有的分子运动可以导致晶体生长，而不涉及实质性的整体扩散。他们将确定，如果用外场放大整体分子运动，玻璃状态下的晶体生长是否会变得更快。他们将研究表面增强的晶体生长是否源于表面增强的分子流动性。首次用表面光栅衰减法测量了有机玻璃的表面扩散系数，并与表面晶体生长速率进行了关联。该项目将研究涂层材料的哪些特性对于抑制表面结晶是重要的。计算机模拟将确定有机玻璃块状和表面晶体生长的潜在机制。对于每种生长模式，将进行筛选实验以评估其普遍性，并将添加聚合物添加剂来扰动它，以进一步了解其机理和控制。非技术摘要：结晶几乎影响到现代技术的每一个方面。虽然对于硬的无机材料已经进行了广泛的研究，但对于有机材料的结晶仍然知之甚少。在这个合作项目中，一个由学术和工业研究人员组成的团队将寻求了解有机玻璃的结晶。玻璃是太冷而无法流动的液体；从制药开发到电信，它们是许多应用的首选材料。该团队将研究液体变成玻璃时新的、快速的晶体生长模式的激活，以及在开发非晶态材料时对这些新模式的控制。这项研究的结果将使晶体生长非常重要的一系列领域的科学家受益；例如，无定形药物和有机电子学。使用无定形固体来提高难溶药物的生物利用度的巨大潜力促使雅培公司与威斯康星大学合作开展这一项目。总部位于芝加哥的雅培酒店距离麦迪逊只有很短的距离，这是一个独特的优势，使合作者之间能够进行密切的互动。研究生和本科生将从这个项目的多学科性质中受益，他们将大量接触实验和模拟、晶体和玻璃、高和低分子有机材料，以及工业和学术研究实验室。这笔助学金支持的人员将与威斯康星大学麦迪逊分校S大学前增富卓越学习机会计划(PEOPLE)合作，该计划在增加少数民族和低收入高中生在高校的招生方面有着良好的记录。该计划提供经验，帮助学生成为具有科学素养的公民，并鼓励他们考虑在科学和工程领域就业。

DMR 0907031 GOALI: Crystallization of Organic GlassesTECHNICAL SUMMARY:In this collaborative project, Profs. Lian Yu, Mark Ediger, and Juan de Pablo of the University of Wisconsin ? Madison, Dr. Geoff Zhang of Abbott Laboratories, and their research student colleagues will investigate the crystallization of organic glasses. Glasses are liquids that are too cold to flow. According to the current view that crystallization is controlled by diffusion, organic glasses should not crystallize readily. Yet recent work has shown that many do crystallize, sometimes at rates 105 times faster than predicted by the standard models. This study concerns two modes of crystal growth activated near the glass transition temperature: a bulk mode and a surface mode. Both growth modes are too fast to be controlled by bulk diffusion. The team will test the hypothesis that molecular motions native to the glassy state can cause crystal growth, without involving substantial bulk diffusion, if sufficient similarity exists between the crystal and liquid structures. They will determine whether crystal growth in the glassy state becomes faster if bulk molecular motions are amplified with an external field. They will study whether surface-enhanced crystal growth results from surface-enhanced molecular mobility. Surface diffusion coefficients of organic glasses will be measured for the first time by the method of surface grating decay and correlated with surface crystal growth rates. The project will examine what properties of coating materials are important for suppressing surface crystallization. Computer simulations will identify the underlying mechanisms of bulk and surface crystal growth of organic glasses. For each growth mode, a screening experiment will be performed to assess its generality and polymer additives will be added to perturb it for further insights on its mechanism and control.NON-TECHNICAL SUMMARY:Crystallization influences almost every aspect of modern technology. While it has been extensively studied for hard inorganic materials, crystallization remains poorly understood for organic materials. In this collaborative project, a team of academic and industrial researchers will seek to understand the crystallization of organic glasses. Glasses are liquids that are too cold to flow; they are the preferred materials for many applications, ranging from pharmaceutical development to telecommunication. The team will study the activation of new, fast modes of crystal growth as a liquid becomes a glass and the control of these new modes in developing amorphous materials. The results of this research will benefit scientists in a range of fields where crystal growth is important; for example, amorphous pharmaceuticals and organic electronics. The enormous potential of using amorphous solids to enhance the bioavailability of poorly soluble drugs has motivated Abbott to partner with the University of Wisconsin in this project. It is a unique advantage that the Chicago-based Abbott is only a short distance away from Madison, enabling close interactions between the collaborators. Graduate and undergraduate students will benefit from the multi-disciplinary nature of this project, having significant exposure to experiments and simulations, crystals and glasses, high and low molecular weight organic materials, and both industrial and academic research labs. Personnel supported by this grant will work with UW-Madison?s Pre-college Enrichment Opportunity Program for Learning Excellence (PEOPLE), which has a proven record of increasing the enrollment of minority and low-income high school students in colleges and universities. This program provides experiences that help students to become scientifically literate citizens and encourages them to consider careers in science and engineering.