The production of chemically‐defined plasma polymers and the introduction of monotype functional groups onto polymer surfaces are described. One method is to lower the energetic level of low‐pressure plasmas. Pressure‐ and plasma‐pulsed plasmas were successfully tested for the production of chemically‐defined plasma polymers by increasing the monomer supply during the plasma‐off period. Well‐defined ultra‐thin polymer films with regular structure were deposited from atmospheric plasmas by electrospray techniques. Post‐plasma wet‐chemical processing was also applied, as were gas/liquid‐based aerosols and underwater plasmas.magnified image

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).

No abstract

Summary: XPS and NEXAFS spectroscopy were used for the chemical characterization of pulsed plasma‐deposited ethylene films before and after exposure to ambient air. The influence of external plasma parameters on the spectroscopic results was investigated. Information on the chemical character of the plasma‐polymerized films, such as the regularity of the primary structure, the amount of long‐living radicals, and branching or cross‐linking or both was derived from this data. “Irregularity” and radical concentration for post‐plasma reactions of the plasma‐deposited films increased with the duty cycle or power. A decreased level of monomer fragmentation and, consequently, an increase in regularity is partially concluded from the experimental data when the monomer pressure is increased. The concentration of surface radicals available for post‐plasma reactions also increased with monomer pressure. The correlation found between the degree of the post‐plasma oxygen incorporation and the variation of the various external parameters agreed with earlier ToF‐SSIMS findings.

No abstract