Introduction of carboxylic groups on ethylene-co-tetra fluoroethylene (ETFE) film surfaces by CO2 plasma

ETFE film surfaces were modified by CO2, O2 and Ar plasmas in order to form carboxylic groups on their surfaces, and the possibility that carboxylic groups could be predominantly introduced into the CH2–CH2 component rather than the CF2–CF2 component in the ETFE polymer chains was investigated from the viewpoint of chemical composition analyzed by XPS. The CO2 plasma modification was more effective in the selectivity of the CH2CH2 component for the introduction of carboxylic groups, as well as in the concentration of the carboxylic groups formed on the film surfaces than O2 plasma modification. The concentration of carboxylic groups formed on the ETFE film surfaces by the CO2 plasma modification was 1.40–1.50 groups per 100 carbons. Topographical changes on the ETFE film surfaces by the plasma modification were also investigated by scanning probe microscopy.