Segmental Dynamics of Surface Bound Polymers

[807696] Blum该奖项将使研究聚合物在界面上的节段运动成为可能，特别是那些附着在固体表面上的聚合物。多相材料（如复合材料、涂层、纳米材料和电子材料）的界面对这些系统的物理性能起着重要的决定作用。由于界面本身非常薄，并且随着结构尺寸的减小，界面的影响变得更加难以用宏观物理测试来正确表征。光谱学技术，特别是氘核磁共振（NMR），将用于研究聚合物与固体基质界面的微观性质。使用氘标记是很重要的，因为特定的氘不会对聚合物的节段运动产生显著的扰动——氘根据它们的位置作为报告基团，这是综合控制的。重点是聚合物片段的动力学（即分子运动）。对节段运动的研究不如对界面结构的研究多；然而，两者都决定了所使用系统的最终属性。这项工作建立在以前由美国国家科学基金会资助的工作的基础上，在那里，氘核磁共振已被证明是探测吸附聚合物运动的有力工具。对于吸附在固体表面上的均聚物，已经确定了单分子厚膜中的运动梯度。然而，这种梯度/层的表征是不完整的。建议在复合材料上进行实验，其中标记的聚合物被吸附在固体基底上，而未标记的聚合物被吸收在其上。这些将确定覆盖层的存在如何影响界面层。随着核磁共振仪器的灵敏度的提高，也提出了二维交换核磁共振实验，以定量估计存在于界面聚合物中的不同运动物质的速率和数量。成功完成这项工作的结果将是界面材料的结构和动力学知识将有助于研究人员设计具有增强性能的界面系统，用于先进的复合结构，电子器件，颗粒稳定和粘合剂性能等先进应用。* * *

9807696 Blum This award will enable study ofthe segmental motion of polymers at interfaces, particularly those attached to solid surfaces. The interfaces in multiphase materials, such as those in composites, coatings, nano- and electronic materials play an important role in determining the physical properties of those systems. Since the interfaces themselves are quite thin, and as the size of structures is reduced, the effects of the interfaces become even more difficult to properly characterize with macroscopic physical testing. Spectroscopic techniques, especially deuterium nuclear magnetic resonance (NMR), will be used to study the microscopic properties of the polymers at interfaces with solid substrates. The use of deuterium labelling is important because specific deuteration is not a significant perturbation of the segmental motion of the polymer-the deuterons act as reporter groups based on their position which is synthetically controlled. The focus will be on the dynamics (i.e. molecular motion) of polymer segments. Segmental motion has not been studied as much as the structures of the interfacial species; however, both determine the ultimate properties of the systems used. This work builds on work previously funded by NSF where deuterium NMR has been shown to be a powerful tool for probing the motions of adsorbed polymers. For homopolymers adsorbed on solid surfaces, a motional gradient in a single-molecule thick film has been identified. However, the characterization of this gradient/layer was incomplete. It is proposed that experiments on composite materials, where the labelled polymer is adsorbed on the solid substrate and an unlabelled polymer is absorbed over it, be performed. These will identify how the presence of an overlayer affects the interfacial layer. With the sensitivity of the NMR instrumentation available, it is also proposed that two- dimensional exchange NMR experiments be performed in order to quantitatively estimate the rates and amounts of different motional species present in the interfacial polymers. %%% The result of the successful completion of this work will be that knowledge of the structure and dynamics of interfacial materials will help researchers to design interfacial systems with enhanced properties for advanced applications such as advanced composite structures, electronic devices, particle stabilization, and adhesive properties. ***