Using Confinement to Study the Colloidal Glass Transition

* 非技术摘要 * 纳米技术的最新进展发现，一些材料在非常小的尺度上表现不同。 例如，较小的物体比较大的物体更容易破碎;但是小于100纳米厚的小塑料片甚至比我们从更厚的塑料片中推断出来的更容易破碎。 塑料是无定形材料，类似于窗户玻璃，现在人们知道，许多玻璃质材料在足够小的样品中表现不同。 然而，有些人变得更强，有些人变得更弱。 这个个人研究者奖支持研究液体中小塑料颗粒的模型系统的实验，当颗粒浓度增加时，该模型系统的行为类似于玻璃。 实验将使用显微镜观察粒子的运动，并观察当样品被限制在两个紧密间隔的平行玻璃板之间时，这种运动是如何变化的。 通过这种方式，将直接观察到系统如何依赖于板之间的间距。 这项研究对于未来的纳米技术应用非常重要，这些应用依赖于由玻璃质材料（如塑料）构建的微小结构。 该项目为本科生和研究生提供培训和教育。 此外，实验室将进行至少一次实地考察，每年为高中学生团体。 这些实地考察让学生动手实验室的经验，和显微镜的视觉性质，很容易让学生兴奋他们的访问。技术摘要 * 聚合物玻璃和分子玻璃的玻璃化转变通常是在宏观大体系的背景下研究的。 然而，限制样品使得一个或多个维度是微观的通常会改变样品的行为，例如改变样品变成玻璃的温度。 这个个人研究者奖支持一个项目，研究限制在薄样品室的胶体悬浮液作为一个模型系统的玻璃化转变在有限的几何形状。 胶体悬浮液由液体中的微观尺寸的固体颗粒组成;如果颗粒浓度足够高，则该系统的行为类似于玻璃。 实验将使用共聚焦显微镜直接观察胶体颗粒的运动以及这种运动在限制中如何变化。 随着越来越多的技术在纳米尺度上建立，了解限制对材料的物理影响变得越来越重要。 该项目为本科生和研究生提供培训和教育。 该实验室每年将为高中学生团体进行至少一次实地考察。 这些实地考察给学生动手实验室的经验，和研究的视觉性质，很容易让学生对他们的访问感到兴奋。

****NON-TECHNICAL ABSTRACT****Recent advances in nanotechnology have discovered that some materials behave differently on a very small scale. For example, smaller objects are easier to break than larger objects; but small pieces of plastic less than 100 nanometers thick are even easier to break than would be expected by extrapolating from what we know about thicker pieces of plastic. Plastics are amorphous materials, similar to window glass, and now it is known that many glassy materials behave differently in small enough samples. However, some become stronger and some become weaker. This individual investigator award supports experiments to study a model system of small plastic particles in a liquid, which behaves analogously to a glass when the particle concentration is increased. The experiments will use a microscope to view the motion of the particles and see how this motion changes when the sample is confined between two closely spaced parallel glass plates. In this way, how the system depends on the spacing between the plates will be directly observed. This research is important for future nanotechnology applications that rely on tiny structures built out of glassy materials such as plastic. This project provides training and education for both undergraduate and graduate students. Additionally, the laboratory will conduct at least one field trip each year for groups of high school school students. These field trips give students hands-on laboratory experiences, and the visual nature of microscopy makes it easy to get students excited about their visit.****TECHNICAL ABSTRACT****The glass transitions of polymer glasses and molecular glasses are usually studied in the context of macroscopically large systems. However, confining samples so that one or more dimensions are microscopic typically changes the behavior of the sample, for example changing the temperature at which the sample becomes a glass. This individual investigator award supports a project to study a colloidal suspension confined in thin sample chambers as a model system for glass transitions in confined geometries. Colloidal suspensions are composed of microscopic-sized solid particles in a liquid; this system behaves analogous to a glass if the particle concentration is sufficiently high. Experiments will use confocal microscopy to directly observe the motion of colloidal particles and how this motion changes in confinement. Understanding the physical effects of confinement on materials is increasingly important today as more and more technology is built at the scale of nanometers. This project provides training and education for both undergraduate and graduate students. The laboratory will conduct at least one field trip each year for groups of high school school students. These field trips give students hands-on laboratory experiences, and the visual nature of the research makes it easy to get students excited about their visit.