Easily grafted polyurethanes with reactive main chain functional groups. Synthesis, characterization, and antithrombogenicity of poly(ethylene glycol)-grafted poly(urethanes)

A novel synthesis of poly(ethylene glycol) (PEG)-grafted poly(urethanes) (P URs) is described based on a precursor PUR containing free amino groups in the main chain. Three different poly(urethane) backbones were prepared: a h omopoly(urethane) comprised of N-Bocdiethanolamine (BDA) and 4,4'-methylene bis(phenyl isocyanate) (MDI), a copoly(urethane) (COPUR) consisting of BDA, N-benzyldiethanolamine and MDI. and a poly(urethane urea) (PUU) that was p repared from BDA, MDI, and ethylenediamine as the chain extender. The M-n o f these poly(urethanes) ranged from 32,000 to 72,000 g/mol. PEG: (750, 1.90 0, and 5,000 g/mol) was grafted onto the boc-deprotected poly(urethanes) vi a the chloroformate. Films of the polymers were spin cast from dilute solut ions, annealed, and the surfaces analyzed by goniometry. Water contact angl e data indicates increasing PEG surface coverage of the poly(urethanes) wit h increasing PEG molecular weight. Reorientation of the polymer films is ev idenced by contact angle hysteresis. Polymer thrombogenicity, which was stu died using blood perfusion experiments, shows that COPUR-g-PEG5000 and PUU- g-PEG5000 exhibit very little platelet adhesion. (C) 1999 John Wiley & Sons , Inc.