Selective Surface Modification of Poly(propylene) with OH and COOH Groups Using Liquid‐Plasma Systems

Underwater plasma and glow discharge electrolysis are interesting new methods for polymer surface functionalization. The achievable content of O‐containing functional groups exceeds that of oxygen glow discharge gas plasmas by a factor of two (up to ca. 56 O/100 C). The percentage of OH groups among all O‐containing groups can reach 25 to 40%, whereas it is about 10% in the gas plasmas. Addition of hydrogen peroxide increases the fraction of OH groups to at most 70% (27 OH/100 C). The liquid plasma systems are also able to polymerize acrylic acid and deposit the polymer as very thin film on substrate surfaces or membranes, thereby retaining about 80% of all COOH functional groups (27 COOH/100 C). magnified image