Defense Date

2012

Document Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Kenneth Wynne

Abstract

The surface response of a polymer substrate to external stimuli such as initial wetting is controlled by the outermost molecular layer. Thus, changes on the nanoscale may be engaged to control macroscale wetting behavior. Our work has predominantly focused on surface modification of conventional polyurethane coatings (HMDI-BD-PTMO). Studies on network constrained phase separation and facile polydimethylsiloxane surface functionalization led to the discovery of a simpler one-step and more general approach to functional polymer surfaces that we have designated as “Bottle-Brush Nanoglass” (BB-NG) after the two principle components: (a) a polyoxetane soft block “spine” with side chain “A” bristles and triethoxysilyl chain ends and (b) an alkoxysilane that together with BB chain ends comprise precursors to a “nanoglass”, NG phase. This paper focuses on the extent of modification for a conventional aliphatic polyurethane using a range of fluoropolyoxetane (poly(trifluoroethoxymethyl-methyl oxetane) diol) or 3F diol based modifier concentrations. Upon generating a blend of the polyurethane with the modifier, the BB-NG which is a minor constituent of the blend, phase separates to provide the topmost layer of the coating. Initial results demonstrate that the modified polymer coatings exhibit an expected increase in contact angles with water. Wetting behavior was characterized using the sessile drop technique as well as Dynamic Contact Analysis (DCA, Wilhelmy Plate). Surface composition as well as near surface topology and morphology are characterized by X-ray Photoelectron Spectroscopy (XPS) and Tapping Mode Atomic Force Microscopy (TM-AFM) respectively. Contrast in phase images reflect the surface modulus and viscoelasticity, from which physical form or compositional differences may be deduced. These characteristics have also been explored in our study by hardness tests via nanoindentation.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

12-13-2012

Included in

Engineering Commons

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