Characterization of the interaction of nitric oxide/nitrogen dioxide with the polymer surfaces in ECMO devices

In this work, the interactions between nitric oxide (NO)/nitrogen dioxide (NO₂) and the polymer materials of a gas exchanger system used in an extracorporeal membrane oxygenation (ECMO) setting are characterized. FTIR-ATR, XPS, and SEM were used to analyze the effects of the gas treatment. The polymer materials used in the gas exchanger system consisted of polymethylpentene (PMP) hollow fiber membranes, inlet/outlet caps made of methyl methacrylate acrylonitrile butadiene styrene (MABS), casting material consisting of polyurethane (PU), and the gas hoses made of polyvinyl chloride (PVC). Gas treatment with NO and NO₂ was conducted, with exposure times ranging from 30 min to 10 days. The gas concentrations range from 80 to 1000 ppm in the case of NO₂ and a maximum of 10,000 ppm in the case of NO. The formation of nitro and nitrate ester groups and nitric acid (HNO3) adsorption on the polymers’ surface was observed using FTIR-ATR and XPS. The investigations showed that these effects depend on exposure time and gas concentration. The alterations persisted over more extended periods. The XPS measurements showed that the reaction only occurred exclusively on the surface of the polymers. The recorded SEM images showed no macroscopic changes in the surface structures of the polymers.