U.S.-France Cooperative Research: Structural and Dynamical Studies of Living Polymers by Neutron Scattering

美法合作研究：通过中子散射对活性聚合物进行结构和动力学研究

• 批准号: 9016061
• 负责人: Sandra Greer
• 金额: $ 1.17万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-04-01 至 1996-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9016061&HistoricalAwards=false
• 关键词: U.S.; France; Cooperative; Research; Structural

This award will support collaborative research in experimental physical chemistry between Dr. Sandra Greer, University of Maryland, and the following French scientists: Professor Pierre Pfeuty, Laboratoire de Physique des Solides, University of Paris-Sud, and Drs. R. Bellissent and F. Boue, Laboratoire Leon Brillouin, Grenoble, France. The objective of the proposed research is to carry out structural and dynamical studies of living polymers by neutron scattering. Living polymers are organic polymers which remain in dynamical chemical equilibrium with their monomers. The monomers come and go from the active polymers. The conversion of monomers to polymers depends on temperature, commencing only below a certain "ceiling temperature". Below the ceiling temperature, the mole fraction and the average chain length of the polymers increase as the temperature is decreased. The investigators propose to study the static and dynamic properties of these polymers by neutron scattering. Dr. Greer and her research group have expertise in the preparation of samples of living polymers which will remain "alive" indefinitely. Dr. Pfeuty is an expert on the statistical mechanics of living polymers, while the investigators at the Laboratoire Leon Brillouin have extensive experience in neutron scattering and polymer research. In this project, samples will be prepared at the University of Maryland and transported to the nuclear reactors at Saclay and Grenoble. Low angle neutron scattering from living polystyrene in deuterated cyclohexane to be carried out at Saclay will provide the investigators with information on the structure of the polymer chains near the polymerization and near the tricritical point, and on the rate of relaxation to the equilibrium chain distribution. Studies with the spin echo neutron spectrometer at Grenoble will provide information on the dynamics of the chain motions. The proposed experiments cannot presently be carried out in the US, because of a lack of high-flux small angle neutron scattering facilities.

该奖项将支持实验性合作研究 桑德拉·格里尔博士， 马里兰州，以及以下法国科学家： 教授 Pierre Pfeuty，大学固体物理学教授 和R. Bellissent和F.布埃 里昂·布里渊，法国格勒诺布尔。 的目的 建议的研究是进行结构和动力 用中子散射研究活性聚合物。 活性聚合物是保持动态的有机聚合物， 与单体的化学平衡。 单体来自 从活性聚合物开始。 单体的转化 对聚合物的影响取决于温度，仅在低于 一定的“天花板温度”。低于上限温度， 的摩尔分数和平均链长， 聚合物随着温度降低而增加。 的 研究人员建议研究静态和动态 这些聚合物的性质通过中子散射。 博士 格里尔和她的研究小组在制备 活的聚合物样本， 无限期 普菲蒂博士是统计学方面的专家 活聚合物的力学，而研究人员在 Leon Brillouin律师在以下方面拥有丰富的经验： 中子散射和聚合物研究。 在本项目中， 样本将在马里兰州大学制备， 运送到萨克雷和格勒诺布尔的核反应堆 聚苯乙烯的小角中子散射 在萨克雷进行的氘代环己烷试验将 向调查人员提供有关结构的信息 聚合物链的聚合附近和附近的 三临界点，并对弛豫率， 均衡链式分布自旋回波研究 格勒诺布尔的中子谱仪将提供有关 链条运动的动力学 拟议的实验 目前在美国还不能进行，因为缺乏 高通量小角度中子散射设施。