Development of Ultrathin Polymer Films and Their Characteristics in Two Dimensions

Abstract

Abstract Nanostructures and properties of ultrathin polymer films prepared by repeated deposition of monolayers have been investigated with emphasis on single chain morphology in two dimensions. The particular characteristics of ultrathin films were successfully revealed by novel optical microscopy and fluorescence spectroscopy techniques. A single polymer chain, which is confined into a two-dimensional plane, takes a contracted conformation, being segregated from other chains in the monolayer. Unlike three dimensional bulk polymers, there is little entanglement of polymer chains even for large molecular weight samples. These characteristics at the molecular level result in the entropy relaxation of individual chains with a small activation energy of diffusion, when the segmental motions are allowed at elevated temperatures. These understandings of structures and properties in two dimensions are indispensable for fabrication and application of polymeric thin films because the fine structures in low dimensions play critical roles in the production of advanced functions.