Synthesis of fluorinated monomer and formation of hydrophobic surface therefrom

Abstract

Fluorine-containing polymers play an important role in coatings. In this paper, a novel route was developed to prepare fluorine-containing copolymers with long perfluoroalkyl side chains. Hydrophobic films were formed from the copolymers and correlative stoichiometric curing agent. In order to prepare the anticipated fluorine-containing copolymers, a new kind of fluorinated monomer was designed and synthesized. The chemical structure of the monomer and the corresponding copolymers were confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR and ¹⁹F NMR). Glass-transition temperature (T_g) of the copolymers was determined with differential scanning calorimetry (DSC). Molecular weight and its distribution of the copolymers were investigated by gel permeation chromatography (GPC). The surface properties of the copolymer films were characterized by static water contact angle, X-ray photoelectron spectrometry (XPS) and atomic force microscopy (AFM). Results showed that the fluorinated monomer and the fluorine-containing copolymers were prepared as expected. Both branching degree and molecular weight of the copolymers increased as fluorine content thereof increased, resulting in an increasing T_g and a broader molecular weight distribution and larger polydispersity. XPS proved an enrichment of the fluorinated segments on the film surfaces. AFM results showed that surface roughness of the copolymer films increased with the use level of the monomer. As a result, the hydrophobicity of the copolymer films was enhanced with the increasing amount of the fluorinated monomer.