Introduction of Modern Light Scattering Methods in Chemistry Laboratories

这项建议旨在将现代光散射仪器引入我们的化学实验室，特别是我们的物理化学和生物化学实验室。无论是合成聚合物还是生物大分子，大分子的表征在很大程度上依赖于分子量和大小的测量。长期以来，光散射技术一直被认为是确定分子量和大小的最佳方法之一。在仪器方面的进步，主要是由于激光和改进的光度检测设备，现在已经使这种技术可以在本科生实验室使用。作为例子，这里提出的几个实验中的两个将允许物理化学学生探索表面活性剂的两嵌段共聚物和胶束溶液的性质：(1)将研究两嵌段共聚物体系从无规卷曲构象到球状构象的转变；(2)将研究在含水表面活性剂体系中自组装聚集体的尺寸和多分散性。生物化学专业的学生将测试GET渗透校准曲线法测量分子量的有效性，并与光散射法测量绝对分子量进行比较。所有计划的实验都通过所要求的仪器而变得非常容易，其数据采集时间节省了实验室时间，使学生能够在目前相同的可用时间范围内探索项目的其他方面，从而丰富他们的实验室经验。新仪器的出现只会鼓励学生更充分地认识到在极其重要的、日益跨学科的高分子科学领域所面临的挑战。

This proposal seeks to introduce modem light scattering instrumentation into our chemistry laboratories, especially our physical chemistry and biochemistry laboratories. The characterization of macromolecules, whether they be synthetic polymers or biological, depends heavily on the measurement of molecular weight and size. Light scattering techniques have long been recognized as one of the best means of determining molecular weight and size. Advances in instrumentation, largely made possible by the laser and improved photometric detection devices, have now made such techniques accessible for use in undergraduate laboratories. As examples, two of the several experiments proposed here will allow physical chemistry students to explore properties of diblock copolymers and micellar solutions of surfactants: (1) the transition from a random coil conformation to a globule conformation will be studied for a diblock copolymer system; (2) the size and polydispersity of self-assembled aggregates in aqueous surfactant systems will be studied. Biochemistry students will test the validity of get permeation calibration curve methods for molecular weight measurements against absolute molecular weight measurements made by light scattering methods. All the planned experiments are made extremely facile by the requested instrumentation whose data acquisition time represents such a saving in laboratory time that students will be able to explore further aspects of the projects on their own thereby enriching their laboratory experiences within the same currently available time frame. The advent of the new instrumentation can only encourage students to appreciate more fully the challenges available in the extremely important, increasingly interdisciplinary field of macromolecular science.