Poly(O-acyl hydroxy L-proline) (II) wetting characteristics and blood clotting on surfaces of poly O-acetyl, butyryl, hexanoyl, dodecanoyl, and benzoyl hydroxy L-proline.

Poly O-acetyl, butyryl, hexanoyl, dodecanoyl, and benzoyl hydroxy L-proline (poly[O-acyl Hyp]s) were evaluated as materials for blood contact by means of contact angle and blood clotting time measurements. Critical surface tensions obtained from Zisman plots for all materials were 22-29 dyn/cm, suggesting that these materials may exhibit good blood compatibility. Dispersion and nondispersion force contributions to the surface tension were gamma ds = 1.4, gamma ns = 49.3 dyn/cm, (11.0, 16.2), (19.8, 3.8), (21.2, 4.6) and (14.1, 10.8) for the poly(O-Acetyl, Butyryl, Hexanoyl, Dodecanoyl and Benzoyl Hyp) surfaces, respectively. The materials showed remarkable wetting differences that were dependent on the type of acyl group attached to Hyp. The values of the dispersion and nondispersion components of the surface tension for poly(O-hexanoyl Hyp) and poly(O-dodecanoyl hyp) were very close to those obtained for glutaraldehyde-treated umbilical cord vessels. The blood clotting times on the respective polymer surfaces, obtained by using the kinetic method, were normalized to those of control glass and siliconized glass surfaces. All the poly(O-acyl Hyp)s surfaces showed longer clotting times than those of the poly(L-proline) and glass surfaces. The surfaces of those polymers having longer aliphatic or aromatic acyl groups had longer clotting times than those of the polymers with relatively shorter groups.