Fluoroalkyl-functionalized Silica Particles: Synthesis, Characterization, and Wetting Characteristics (Preprint)
Abstract
Fluoroalkyl-functionalized silica particles for use in non-wetting surfaces were prepared by treatment of silica particles with fluoroalkyl-functional chlorosilanes. Both fumed and precipitated silica were studied, as well as the efficiency of surface coverage using mono-, di-, and tri-functional chlorosilanes. The most-effective surface treatment was accomplished via the surface grafting of mono-functional-chlorosilanes in the presence of pre-adsorbed dimethylamine under anhydrous conditions at room temperature. Confirmation of covalent attachment was accomplished via FT-IR spectroscopy, while elemental analysis, thermogravimetric analysis, and nitrogen adsorption isotherms were used to determine grafting densities and additional key geometric characteristics of the grafted layer. The effect of residual silanol content on the moisture uptake properties of the modified silica particles was determined by measuring the water uptake of unbound particles, while liquid wetting properties were determined by dynamic contact angle analysis of elastomeric composites. Although residual silanol content was shown to effect wetting properties, results suggest that surface geometry dominates the performance of liquid-repellent surfaces. The potential use of fluoroalkyl-functionalized silica particles for hydrophobic and oleophobic applications is discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 03, 2011
- Accession Number
- ADA546301
Entities
People
- Andrew J. Guenthner
- Joseph M Mabry
- Raymond Campos
- Timothy S. Haddad
Organizations
- Air Force Research Laboratory