REU Supplement: Characterization of Polymer Interphases Using Surface-Enhanced Raman Scattering

一种被称为表面增强拉曼散射（SERS）的创新分析技术正在与其他表面分析技术相结合，用于对聚合物系统吸附在金属基体上或固化时形成的“界面相”进行无损表征。SERS被用于研究嵌段共聚物和均聚物混合物在银和铜等基质上的吸附。SERS也被用来确定金属底物对聚合物分子结构的影响。目标是获得有关金属催化或抑制固化反应的基本信息，金属基质上吸附聚合物的构型，聚合物系统组分在金属上的优先吸附，聚合物和小分子与金属相互作用的机制，固化程度是指从金属表面到固化在金属上的聚合物的距离的函数，以及金属离子向固化在金属底物上的聚合物的迁移。诸如聚合物系统的组分优先吸附到底物上以及由底物催化或抑制聚合物内的反应等过程导致在靠近底物的聚合物中形成具有与本体聚合物不同的化学和物理性质的界面相。由于粘接键和复合材料的宏观性能是由界面相控制的，因此确定和控制界面相的分子结构是至关重要的。SERS是这一目的的理想选择，因为它本身具有表面选择性，并且不需要像几乎所有其他表面分析技术那样将聚合物从基质中分离出来进行间相检测。所得结果被用于调整界面的分子结构，从而在结构粘合剂接头和复合材料中获得增强的环境稳定性。

An innovative analytical technique known as surface-enhanced Raman scattering (SERS) is being used in combination with other surface analysis techniques for the non-destructive characterization of "interphases" formed when polymer systems are adsorbed onto or cured against metal substrates. SERS is being used to investigate the adsorption of block copolymers and mixtures of homopolymers onto substrates such as silver and copper. SERS is also being used to determine the effect that metal substrates have on the molecular structure of polymers cured against them. The goal is to obtain fundamental information regarding catalysis or inhibition of curing reactions by metals, configurations of polymers adsorbed onto metal substrates, preferential adsorption of components of polymer systems onto metals, mechanisms by which polymers and small molecules interact with metals, extent of cure as a function distance away from a metal surface and into a polymer cured against the metal, and migration of metal ions into polymers cured against metal substrates. Processes such as preferential adsorption of components of a polymer systems onto a substrate and catalysis or inhibition of reactions within the polymer by the substrate lead to the formation of an interphase in the polymer adjacent to the substrate that has chemical and physical properties distinct from those of the bulk polymer. Since the macroscopic properties of adhesive bonds and composites are controlled by the interphase, it is essential to determine and control the molecular structure of interphases. SERS is ideal for this purpose since it is inherently surface selective and does not require a polymer to be separated from a substrate for the interphase to be examined as do virtually all other surface analysis techniques. The results obtained are being used to tailor the molecular structure of interphases so as to obtain enhanced environmental stability in structural adhesive joints and composites.