Pulsed plasma-polymerized 2-isopropenyl-2-oxazoline coatings: Chemical characterization and reactivity studies

Thin coatings were deposited by means of low pressure plasma polymerization of 2-isopropenyl-2-oxazoline (2-IOX). Depositions were performed in the pulsed mode, exploiting the carbon-carbon double bond of the monomer, in order to maximize the retention of oxazoline rings in the coatings. The wettability of the thin films was assessed by water contact angle measurements, while their stability was investigated by immersion in different aqueous environments (Phosphate Buffer Saline (PBS) at 37 °C and aqueous solutions with different pH) and was found to be dependent on the deposition conditions. Chemical characterization of the coatings was performed by means of Attenuated Total Reflectance Fourier Transform Infrared (FTIR/ATR) spectroscopy, Nuclear Magnetic Resonance (1H NMR) spectroscopy and Gel Permeation Chromatography (GPC). All these techniques allowed to assess the retention of oxazoline ring, which can be exploited through reaction of the plasma deposited coatings with carboxylic acid groups. To this end, reactions with poly(acrylic acid) in different conditions (temperature, reaction time) were investigated.