Reaction of CO2Gas with (radicals in) Plasma-Polymerized Acrylic Acid (and Formation of COOH-Rich Polymer Layers)

Abstract

In contrast to most of the existing literature on plasma polymerization of acrylic acid (AA), not only the chemical structure and film thickness of the deposits were studied, but also a new way to obtain COOH-rich surfaces were studied. This is an important aspect when applying the obtained coatings for biomedical and electronics applications. Therefore, acrylic acid/CO2 polymer films with a thickness of ca. 150 nm were deposited in the pulsed plasma regime onto polyethylene and aluminum. Their structure–property relationships were studied in dependence on the mixture ratio of acrylic acid monomer and CO2 gas. The influence of the CO2 gas on the regularity and functionality of plasma-deposited poly(acrylic acid) (PAA) was studied in detail using bulk-sensitive (FTIR) as well as surface-sensitive methods, such as X-ray photoelectron spectroscopy. Results obtained show, in presence of a small amount of CO2 gas within the acrylic acid plasma, a structure of PAA with high concentration of COOH groups was estimated. A polymer network is obtained with an increasing abundance of branched groups for AA/CO2 with increasing CO2 gas in the mixture.