Experiments on the Internal Structure of Latexes Using SmallAngle Neutron Scattering

本研究的目的是获得关于 形成的动力学以及这些动力学如何影响最终的 乳胶粒子的结构。 这些材料被用作涂料 和油漆，也用作抗冲改性剂。 这项工作的价值， 现代工业是，随着对 乳胶粒子的结构和行为，更好的材料可以 制作。 与成膜动力学、膜的强度有关的问题 材料和特殊用途应用，包括医药和 生物技术依赖于对结构的详细了解， 乳胶的行为。 结构化乳胶是亚微米尺寸的颗粒，具有一些独特的 内部形态，悬浮在流体介质中，通常是水。 当链的尺寸约为胶乳的一半时， 直径，存在某种类型的偏析，第一个 聚合材料出现在颗粒的中心附近。 从技术上讲，最重要的结构化乳胶是 具有橡胶状核和玻璃状壳的核-壳型。 这种类型 一般代表高抗冲聚合物，更具体地说，ABS （丙烯腈-丁二烯-苯乙烯）塑料和丙烯酸冲击 修饰语 PI计划研究均聚物和共聚物乳胶 使用小角中子散射（SAS）来跟踪 聚合法 为了阐明均聚物结构，聚苯乙烯将 被利用 他们计划测试这样一个假设， 分子尺寸约为胶乳粒径的一半分离 看起来像是一个核和一个壳，第一个聚合的 链倾向于靠近颗粒的中心。 问题 在单体的第二部分之前存在多少分离 是聚合的，以及在聚合过程中， 聚合，将是计划实验的主题。 模型 假设系统的内部粘度高，和/或 玻璃化正在发生，最后的系统在其玻璃之下 转变温度和聚合物可溶于单体。 为了观察共聚物系统，小角中子散射 测量将在第二聚合物聚合之前进行。 组件启动，并在 聚合法 结果应阐明， 如果没有，则随着时间的推移， 系统的内粘度增加和/或如果玻璃 探讨了单体增塑颗粒的转变。

The purpose of this research is to obtain basic information about the kinetics of formation and how these kinetics affect the final structure of latex particles. These materials are used as coatings and paints, also as impact modifiers. The value of this work to modern industry is that with an improved understanding of the structure and behavior of latex particles, better materials can be produced. Questions relating to film formation kinetics, strength of materials, and special purpose applications including medicine and biotechnology depend on a detailed knowledge of the structure and behavior of the latexes. Structured latexes are submicron sized particles, with some unique internal morphology, suspended in a fluid medium, most often water. When the dimensions of the chains are about half those of the latex diameter, some type of segregation is present, with the first polymerized material appearing near the center of the particle. Technologically, the most significant structured latex is the core-shell type with a rubbery core and a glassy shell. This type generically represents high-impact polymers, and more specifically ABS (acrylonitrile-butadiene-styrene) plastics and acrylic impact modifiers. The PIs plan to look at both homopolymer and copolymer latexes using small-angle neutron scattering (SAS) to follow the course of the polymerization. To elucidate homopolymer structure, polystyrene will be used. They plan to test the hypothesis that polystyrene of molecular dimension about half of the latex particle size segregates into what appears to be a core and a shell, with the first polymerized chains tending to be near the center of the particle. The question of how much segregation exists before the second portion of the monomer is polymerized, and how the extent of segregation changes during polymerization, will be the subject of planned experiments. The model assumes that the internal viscosity of the system is high, and/or vitrification is occurring, the final system being below its glass transition temperature, and the polymer soluble in the monomer. To look at copolymer systems, small-angle neutron scattering measurements will be made before polymerization of the second component is initiated, and several times during the polymerization. The results should elucidate if segregation occurs or, if not the rate of desegregation decrease as the internal viscosity of the system increases and/or if the glass transition of monomer-plasticized particles is approached.