Surface modification of polyethylene by photoinitiated introduction of sulfonic acid groups

The surface of polyethylene (PE) was modified by photochemical introduction of sulfonic acid groups (FI-SO3H). Polyethylene (LDPE as well as HDPE) was irradiated with UV light in the presence of SO2 and O2. The presence of sulfonic acid groups at the PE surfaces was proved by FTIR, REM-EDX and XPS measurements. The presented method of surface modification works under atmospheric pressure and is therefore considered as an inexpensive alternative to plasma modification techniques. Patterned surface modification as well as successful transformations of the sulfonic acid groups to sulfochloride and sulfonamide groups are demonstrated. The modified surfaces may find applications for coating technology and for biochemical / biomedical purposes.