Molecular Dynamics in Self-assembled Monolayers and Polymers studied via sensitive Dielectric Spectroscopy

Abstract

For many molecular systems, interpreting experimental molecular dynamics, by studying the response of a system to external stimuli, is a difficult task. Often the experimental response cannot be reasonably connected to a specific molecular motion. The aim of this work is to examine molecular systems where this difficulty can be overcome. We use sensitive dielectric spectroscopy to investigate the molecular dynamics of two different systems, chlorosilane self-assymbled monolayers and modified siloxane polymers. The polymers studied responded to changes in their surrounding media by altering their wetting characterstics. Because this macroscopic responsive is present, we are able correlate the microscopic response (as measured by dielectric spectroscopy) to likely molecular motions. The goal of the self-assembled monolayer work is similar albeit by a different approach. In this case, the degrees of freedom were limited by using surface bound molecules. By controlling the molecular density we are able to investigate both local, non-cooperative motions as well as interacting dynamics. Specifically, we will show a connection between the interacting dynamics of the self-assembled monolayers to glass transitions found in more complicated materials.