Spectroscopic Study of the Chemistry at the Cr−PMMA Interface

Abstract

The chemical reactivity of metal nanoclusters is largely determined by the size of the particles, and therefore the control of particle size in a given medium has been the topic of several interesting studies in recent years. In most of these studies, polymer molecules are used as stabilizing agents in the aggregation process of the nanoclusters, through their selective adsorption onto the surface of the growing particles, thus forming a barrier to van der Waals attractions. These interactions have resulted in the control of cluster growth without causing any detectable damage to the polymer. Despite a multitude of qualitative observations, no quantitative analysis has been provided to date which offers a relationship between the extent of the metal−polymer interactions (including the degree of damage to the polymer chain) and the size of the metal particles formed as a result of the polymer adsorption. To establish such a relationship and develop the basis for a theoretical and quantitative description of these processes, a fundamental understanding of the nature, strength, and mechanism of the metal−polymer interactions is necessary. In this work, metal surfaces have been used as models for metal particles. The interactions between chromium surfaces and thin films of adsorbed poly(methy methacrylate) have been investigated by X-ray photoelectron (XPS) and surface-sensitive infrared (PM-IRRAS) spectroscopies. The adsorption process results in the formation of a new species at the interface between chromium and PMMA, characterized by distinct spectral patterns, the reorganization of the metal surface molecules, and the reorientation of the polymer ester side chains.