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

一种名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结合使用，以无损地表征当聚合物体系吸附在金属衬底上或固化到金属衬底上时形成的“中间相”。SERS正被用于研究嵌段共聚物和均聚物混合物在银和铜等底物上的吸附。SERS还被用来确定金属衬底对针对它们固化的聚合物的分子结构的影响。目的是获得关于金属对固化反应的催化或抑制、吸附在金属基质上的聚合物的构型、聚合物体系的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理等基本信息。固化程度作为远离金属表面并进入针对金属固化的聚合物的距离的函数，以及金属离子向针对金属衬底固化的聚合物的迁移。诸如优先将聚合物体系的组分吸附到基材上以及由基材催化或抑制聚合物内的反应的过程导致在与基材相邻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。由于胶粘剂和复合材料的宏观性质受界面相控制，因此确定和控制界面相的分子结构是非常必要的。表面增强拉曼光谱是实现这一目的的理想选择，因为它本质上是表面选择性的，并且不需要像几乎所有其他表面分析技术那样，为了检测界面相而将聚合物从基质中分离出来。所获得的结果正被用于调整中间相的分子结构，以便在结构胶接接头和复合材料中获得更好的环境稳定性。

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.