Year of Publication

2004

Document Type

Dissertation

College

Engineering

Department

Materials Science and Engineering

First Advisor

Lynn S. Penn

Abstract

This dissertation describes a study of the kinetics of formation of tethered polymer layers. Polymer chains diffuse from dilute solution to the surface a solid, to which they become attached by one end. Kinetics profiles composed of three distinct regimes are displayed by all tethering reactions studied in the absence of segmental adsorption, regardless of solvent quality, temperature, chemistry of polymer, architecture of polymer, and type of reactive site on the surface. The first regime, fast and predicted previously by theory, is controlled by diffusion of the polymer chains through solution to the bare surface. The second regime, slow and also predicted by theory, is controlled by diffusion of the polymer chains through the already tethered layer. The third regime, relatively fast and not predicted by theory, appears to be the consequence of cooperative interaction between incoming chains and tethered chains. During the tethering process, each tethered polymer chain changes from a random-coil-like configuration to a vertically stretched configuration. The end of the first regime corresponds to completion of a layer of nonoverlapping, coil-like tethered chains, called a mushroom layer. Cessation of tethering corresponds to a layer of vertically stretched chains, called a polymer brush. Transition from mushroom to brush mainly takes place in the third regime and develops in spatially nonuniform manner. The understanding gained about the kinetics of tethering was used to construct simply tethered layers, bi-component tethered layers, bidisperse (two molecular weights) tethered layers, and tethered layers of mixed architecture (linear and star-branched).

Share

COinS