Association, Segregation, and Transport in Copolymer Liquids

共聚物液体中的缔合、分离和传输

• 批准号: 9901087
• 负责人: Timothy Lodge
• 金额: $ 35.4万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9901087&HistoricalAwards=false
• 关键词: Association; Segregation; Transport; Copolymer; Liquids

9901087LodgeMulticomponent polymers in general, and block copolymers in particular, offer attractive routes to novel properties, by the incorporation of disparate chemical elements into materials with prescribed morphologies. However, the important dynamic properties of such mixtures are rather poorly understood. Complications arise due to the presence of structure, which presents barriers to transport, and by the unkown effects of mixing on the chain dynamics. The unifying philosophy of this proposal is that the collective dynamic response of a multicomponent polymer system can only be understood if the underlying structure, mechanisms of motion, and individual component contributions are known. Experimental studies addressing three fundamental issues in this area will be pursued. First, the transient states of aggregation that may exist upon disordering block copolymer melts from the sphere morphology, and upon disordering block copolymer solutions in solvents of varying selectivity, will be characterized. The former topic has received some experimental attention in the literature, but the results are controversial; the latter has not been addressed systematically. Second, the mechanisms of motion of strongly-segregated block copolymers will be delineated, particularly through measurements of chain diffusion along, and perpendicular to, the cylinder axis in oriented samples. This study builds on a previous exploration of the weakly-segregated regime, and will be relevant to most copolymer materials, which are typically more strongly-segregated. Third, the composition and temperature dependence of the monomeric friction factors of the two components of exemplary immiscible mixtures will be examined. This work exploits recently-developed approach involving disordered multiblock copolymers that circumvents the phase separation problem.Polymers are ubiquitous in contemporary technology, but future advances in their application will rely on incorporating several different components into one material, while controlling structure on the microscopic level. Such microstructures can have profound effects on the flow properties of molten polymers, which in turn control the processing of polymers into films, fibers, and three-dimensional objects. This proposal seeks to gain fundamental insight into the way molecular parameters of the several components impact the flow properties of the resulting multicomponent polymer materials.

9901087Lodge多组分聚合物，特别是嵌段共聚物，通过在具有指定形态的材料中加入不同的化学元素，提供了获得新性能的诱人途径。然而，人们对这类混合物的重要动力学性质知之甚少。复杂性的产生是由于结构的存在，这对运输造成了障碍，以及混合对链动力学的未知影响。这一建议的统一理念是，只有当基本结构、运动机制和单个组分的贡献已知时，才能理解多组分聚合物体系的集体动态响应。将进行试验性研究，解决这一领域的三个基本问题。首先，将表征无序的嵌段共聚熔体从球体形态和在不同选择性的溶剂中无序的嵌段共聚溶液中可能存在的聚集的瞬时状态。前者在文献中得到了一些实验性的关注，但结果是有争议的；后者还没有得到系统的讨论。其次，将描述强分离嵌段共聚物的运动机制，特别是通过测量定向样品中沿圆柱轴和垂直于圆柱轴的链扩散。这项研究建立在先前对弱分离制度的探索基础上，并将适用于大多数共聚材料，这些材料通常是更强分离的。第三，将考察示范不相容混合物的两个组分的单体摩擦因数的组成和温度依赖性。这项工作利用了最近开发的涉及无序多嵌段共聚物的方法来规避相分离问题。聚合物在当代技术中普遍存在，但未来在其应用方面的进展将依赖于将几个不同的组分结合到一种材料中，同时在微观水平上控制结构。这种微观结构可以对熔融聚合物的流动特性产生深远的影响，进而控制聚合物加工成薄膜、纤维和三维物体。这项提议试图从根本上洞察几个组分的分子参数如何影响所产生的多组分聚合物材料的流动特性。