Polyurethane (PU), based on poly(dimethyl
siloxane) (PDMS) as a soft segment, with monomethoxy poly(
ethylene glycol) (
MPEG) grafted onto it, was synthesized as a new polymeric
biomaterial for coating PDMS-based biomedical devices. Two different chain extenders,
ethylene glycol (EG) and diethyl bis(hydroxymethyl)
malonate (DBM), were used for the synthesis of PDMS-based
PUs and then
MPEG was grafted onto them by
allophanate and esterification reactions, respectively. Their molecular structures were confirmed qualitatively and quantitatively using FT-IR and 1H-NMR measurements. PDMS-based PU was more hydrophobic than
Pellethane, which is a commercial biomedical-grade poly(
ether urethane), due to the PDMS-rich phase at the polymeric surface. However, the incorporation of
MPEG in PDMS-based PU induced an increase in hydrophilicity. Analyses of their morphology using dynamic mechanical analysis and differential scanning calorimetry showed that the degree of phase separation increased with the content of hard segments. It also showed that
MPEG is compatible with a hard segment consisting of
4,4'-diphenylmethane diisocyanate (MDI) and DBM, while being incompatible with one consisting of MDI and EG. Platelet adhesions with PDMS-based
PUs were significantly reduced when compared with
Pellethane. It was also observed from a platelet adhesion experiment that the incorportion of
MPEG further reduced platelet adhesion. PDMS-based
PUs with
MPEG grafts, which have few hard segments and a distinct PEG phase, exhibited the least platelet adhesion among the
polymer samples tested.