Thermal and environmental stability of poly(4-ethynyl-p-xylylene-co-p-xylylene) thin films

The aim of this paper was to test the thermal and environmental stability of poly(4-ethynyl-p-xylylene-co-p-xylylene) thin films prepared by chemical vapor deposition (CVD) and to optimize the reaction conditions of the polymer. Fourier transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and fluorescence microscopy were employed to investigate the stability of the reactive polymer coatings in various environmental conditions. Chemical reactivity of the thin films were then tested by Huisgen 1,3-dipolar cycloaddition reaction (“click” reaction). The alkyne functional groups on poly(4-ethynyl-p-xylylene-co-p-xylylene) thin films were found to be stable under ambient storage conditions and thermally stable up to 100 °C when annealed at 0.08 Torr in argon. We also optimized the click reaction conditions of azide-functionalized molecules with poly(4-ethynyl-p-xylylene-co-p-xylylene). The best reaction result was achieved, when copper concentration was 0.5 mmol/L, sodium ascorbate concentration to copper concentration was 5:1. In contrast, the azide concentration and temperature had no obvious effect on the surface reaction.

Graphical abstractThe poly(4-ethynyl-p-xylylene-co-p-xylylene) thin film prepared by chemical vapor deposition was thermally stable up to 100 °C in vacuum and environmentally stable under different storage conditions. Huisgen 1,3-dipolar cycloaddition (“click” reaction) was conducted and the surface reaction parameters were optimized.Figure optionsDownload full-size imageDownload as PowerPoint slide