Novel Fluorous Hybrid Surface Modification Characterized by Wetting Dynamics, Morphology and Nanomechanics

<p>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.</p>

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Engineering

Year dc:date.available

2012

Author dc:creator

• Nair, Sithara

Contributors dc:contributor

• Kenneth Wynne

• Polymer
• polyurethane
• polyoxetane
• afm
• dca
• surface modification
• sessile drop
• 3FOx
• wynne
• nanoindentation
• phase separation
• flourous
• coating
• Engineering

Statement dc:rights

• © The Author

Identifier

https://scholarscompass.vcu.edu/etd/446

OAI identifier oai:identifier

oai:scholarscompass.vcu.edu:etd-1445