Formation Mechanisms and Properties of Semifluorinated Molecular Gradients on Silica Surfaces

Published

January 17, 2006

Author(s)

Jan Genzer, K Efimenko, Daniel A. Fischer

Abstract

The goal of this study is to elucidate the formation of molecular gradients made of semifluorinated organosilanes (SFO) on flat substrates by using a methodology developed by Chaudhury ad Whitesides [Science 1992, 256, 1539]. We use surface-sensitive combinatorial near-edge x-ray absorption fine structure spectroscopy (combi-NEXAFS) to measure the position-dependent concentration and molecular orientation of SFO's in the molecular gradients on surfaces. Using the NEXAFS data we establish the correlation between the fraction the F8H2 species on the substrate and the average title angle of the -(CF2)gF group in SFO as a function of the deposition gas medium (air vs. nitrogen) and the end-group around the silicon atom (mono- vs. tri-functional). We also utilize the gradient geometry to comprehend the mechanism of formation of SFO self-assembled monolayers (SAMS). We provide evidence that depending on the nature of the end-group in the SFO and the vapor phase the SFO molecules add themselves into the existing SAMs either as individual molecules or as multimolecular complexes.

Citation

Langmuir

Volume

22

Pub Type

Journals

Keywords

gradients, NEXAFS, SAMs

Citation

Genzer, J. , Efimenko, K. and Fischer, D. (2006), Formation Mechanisms and Properties of Semifluorinated Molecular Gradients on Silica Surfaces, Langmuir (Accessed September 27, 2023)