Effect of hydrophilic soft segment side chains on the surface properties and blood compatibility of segmented poly (urethaneureas)

Segmented poly(urethaneureas) with hydrophilic side chains were prepared from poly(tetramethylene oxide) (PTMO), 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and a diol with a long hydrophilic side chain comprised of an ethylene oxide-proplene oxide copolymer. The end groups of the hydrophilic chains were either sodium sulfonate or methoxy groups. The state of microphase separation showed a small dependence on the fraction of long-chain hydrophilic diol. Surface analysis by means of static underwater contact angle and dynamic contact angle measurements revealed that the graft chains were at the aqueous interface in the hydrated state. An ex vivo A-V shunt experiment revealed that a more thrombogenic blood-material response was correlated with an increase in the concentration of polymeric hydrophilic side chain incorporation. The polyurethane containing a long chain diol with methoxy end groups exhibited a higher level of thrombogenicity than the similar polymers possessing a sulfonate terminated side chain.