Characterization of Plasma-Polymerized Allylamine Using Waveguide Mode Spectroscopy

Abstract

Amine-functionalized thin films were prepared by plasma-induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed conditions to control the film chemistry. The chemical and physical nature of plasma-polymerized allylamine films was investigated, as well as the effect of solvent treatment on the structure of the polymeric material. The film properties were studied using Waveguide Mode Spectroscopy (WaMS), which enabled an independent determination of film thickness and refractive index. Fourier transform infrared (FTIR) spectroscopy showed that changes in duty cycle led to different film chemistries. WaMS carried out on thin films (d < 60 nm) showed changes in the refractive index with increasing thickness believed to suggest intermolecular reactions occurring in the bulk while the film is depositing. All films studied showed a significant loss of soluble material from the surface upon solvent extraction. After extraction however, the films were stable and could be reversibly swollen in ethanol.