Role of Chain Architecture on the Properties of Linear and Star Chain Thin Film Polymer Systems

链结构对线性和星链薄膜聚合物体系性能的作用

• 批准号: 0906425
• 负责人: Peter Green
• 金额: $ 52万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0906425&HistoricalAwards=false
• 关键词: Role; Chain; Architecture; Properties; Linear

TECHNICAL SUMMARY: While during the last decade significant progress has been made toward understanding and controlling the structure and properties of polymers at the nanoscale, major challenges and opportunities, both scientific and technological, remain. Research has largely been devoted to the properties of linear-chain polymer systems; the influence of polymer chain architecture on the properties of thin films has largely remained unexplored. The goal of this proposal is to understand the effect of chain architecture on the miscibility, dynamics, glass transition and aging phenomena in thin film linear/star molecule and star/star molecule mixtures. There are several reasons for studying star polymers. Star molecules suffer a smaller loss in entropy than linear chains upon adsorption at interfaces. In additional to their interfacial properties, the dynamics of star shaped molecules, specifically the longest relaxation time, ?ä, and the viscosity, ?Ø, are slow; ?ä and ?Ø scale exponentially with the degree of polymerization, N, of the chain arm length. Perhaps the most fascinating aspect of star shaped molecules is that for low functionalities, f, and for sufficiently large N, they exhibit properties similar to linear chains. However, for very large f, they exhibit behavior akin to colloids. Guided by theoretical predictions, an experimental program, which exploits tools that include neutrons, electrons, X-rays, dielectric spectroscopy, ellipsometry and mechanical instruments, has been designed to develop an understanding of the influence of confinement and interfacial interactions on miscibility, microstructure, structural instabilities, aging phenomena and dynamics in star shaped molecule based systems (linear/star molecule and star/star molecule mixtures). The properties of these systems promise to be truly fascinating and present intriguing possibilities for new science and applications.NON-TECHNICAL SUMMARY: Diverse technologies, from coatings to functional materials for organic electronic devices and sensors, rely on the properties and performance of polymer thin films. Research on thin polymer films has primarily been devoted to linear chain polymers; little is understood about the properties of chains of different architectures, such as star shaped polymers. Star shaped molecules, by virtue of their architecture offer a number of potential, and unique, advantages over linear chain systems for certain applications. For example, they show promise for adhesive applications, and potentially for certain battery and sensor applications, as it is possible to take advantage of the multi-arm architecture for attachment of molecules/nanoparticles of varying functionalities. The goal of this proposal is to develop an understanding of the role of chain architecture on properties (miscibility, aging phenomena, glass transition and dynamics) of linear chain/star shaped molecule and of star/star molecule mixtures. This is an interdisciplinary program, involving polymer physics, chemistry, interfacial science, thermodynamics and transport processes. It will include an ethnically diverse group, including under represented minorities, of undergraduates, PhD students and high school students. The program also includes an international collaborator in the area of materials synthesis. Outreach activities of the principal investigator include public lectures at technical meetings, retired groups and participation on various National Research Council studies and boards and technical society committees.

技术概要：虽然在过去的十年中，在理解和控制纳米级聚合物的结构和性能方面取得了重大进展，但科学和技术方面的重大挑战和机遇仍然存在。 研究主要致力于线性链聚合物系统的性能;聚合物链结构对薄膜性能的影响在很大程度上尚未探索。本研究的目的是了解线性/星星分子和星星/星星分子混合物中链结构对结晶性、动力学、玻璃化转变和老化现象的影响。研究星星聚合物有几个原因。星星分子在界面吸附时的熵损失比线性链小。 除了它们的界面性质，动态的星星形状的分子，特别是最长的弛豫时间，？和粘度，？慢，慢;？然后呢？分子量与链臂长度的聚合度N成指数关系。也许星星形分子最吸引人的方面是，对于低官能度f和足够大的N，它们表现出类似于线性链的性质。 然而，对于非常大的f，它们表现出类似于胶体的行为。在理论预测的指导下，设计了一个实验方案，利用包括中子、电子、X射线、介电谱、椭圆偏振仪和机械仪器在内的工具，以了解约束和界面相互作用对结晶性、微观结构、结构不稳定性、基于星星形状分子的系统（线性/星星分子和星星/星星分子混合物）中的老化现象和动力学。 这些系统的性能承诺是真正迷人的，并提出有趣的可能性，为新的科学和应用。非技术摘要：各种技术，从涂料到有机电子器件和传感器的功能材料，依赖于聚合物薄膜的性质和性能。 对聚合物薄膜的研究主要致力于线性链聚合物;对不同结构的链的性质，如星星形聚合物，了解甚少。 对于某些应用，星星形分子凭借其结构提供了许多潜在的、独特的优于线性链系统的优点。例如，它们显示出用于粘合剂应用的前景，并且可能用于某些电池和传感器应用，因为可以利用多臂架构来附着不同功能的分子/纳米颗粒。本提案的目标是发展的作用链结构的性质（可溶解性，老化现象，玻璃化转变和动力学）的线性链/星星形分子和星星/星星分子混合物的理解。这是一个跨学科的计划，涉及聚合物物理，化学，界面科学，热力学和运输过程。 它将包括一个种族多样的群体，包括代表性不足的少数民族，本科生，博士生和高中生。 该计划还包括材料合成领域的国际合作者。 主要研究者的外展活动包括在技术会议、退休团体上进行公开讲座以及参与国家研究理事会的各种研究、董事会和技术协会委员会。