PDMS-based
polyurethanes (
PUs) grafted with monomethoxy poly(
ethylene glycol) (
MPEG) were synthesized to develop a coating material for
urinary catheters with a
silicone surface for minimizing
urinary tract infections.
MPEG was grafted on PDMS-based
PUs by two methods depending on the PU synthetic routes: esterification and
allophanate reactions. It was confirmed from mechanical characterization that an increase of the hard segment amount enhanced the ultimate strength and Young's modulus, while reducing elongation at the end-points. The incorporation of
MPEG in PDMS-based
PUs induced a decrease in tensile strength and Young's modulus, and increased elongation at the break point due to its high flexibility. When hydrated in distilled water, mechanical properties of all
PUs synthesized in this study deteriorated due to water absorption. It was evident from the bacterial adhesion test that PDMS-based
PUs showed moderate resistance to adhesion of E. coli on their surfaces compared to
Pellethane, while the incorporation of
MPEG significantly enhanced repellency to bacteria, including E. coli and S. epidermidis. We also studied the release behavior of an
antibiotic drug,
rifampicin, from the polymeric devices fabricated by
solvent evaporation. Although
rifampicin is hydrophilic and soluble in pH 7.4
phosphate buffer, it showed a sustained release over 45 days from PDMS-based
PUs with
MPEG that were grafted on
ethylene glycol residues by
allophanate reaction. This release characteristic was predominantly influenced by a hydrogen bond interaction between the
polymers and
rifampicin, which was confirmed through an ATR-IR study. This may imply that the specific interaction is responsible for the delayed release. Considering the mechanical properties, morphologies of
drug-incorporated polymeric matrices, and drug release behaviors, PDMS-based PU with
MPEG that were grafted on
ethylene glycol (a chain extender) residues by
allophanate reaction showed better material properties for uretharal
catheter coating pusposes in order to minimize
urinary tract infections.