Preparations of Aromatic Diamine Monomers and Copolyamides Containing Phosphorylcholine Moiety and the Biocompatibility of Copolyamides

The synthesis of a novel aromatic diamine compound containing phosphorylcholine (PC) group was carried out to prepare aromatic polyamides with PC moiety, in order to develop durable biocompatible polymer materials. The desired diamine compound, 2-(3,5-diaminophenylcarbonyloxy)ethyl phosphorylcholine (DAPC), was prepared from a reaction of 2-[2-(3,5-dinitrophenylcarbonyloxy)ethyl]-2-oxo-1,3,2-dioxaphospholane with trimethylamine, followed by the reduction of the dinitro group by H2/Pd. The starting phospholane compound was synthesized by a condensation reaction of 2-hydroxyethyl 3,5-dinitrobenzoate with 2-chloro-2-oxo-1,3,2-dioxaphospholane. The polycondensation of DAPC with 4,4′-diamino-3,3′-dimethyldiphenylmethane and isophthaloyl chloride gave the copolyamides with different PC contents. From the results of contact angle of water and XPS analysis on the surface of the copolyamide coating films, it was found that PC units were concentrated on the surface after immersed in water. In addition, by using 2,2-bis[4-(aminophenyloxy)phenyl]propane or 2,2-bis[4-(aminophenyloxy)phenyl]hexafluoropropane as a diamine comonomer with DAPC, high molecular weight copolyamides containing PC moiety were obtained to prepare homogeneous coating films. The obtained copolyamides exhibited the high thermal stability, and also the excellent biocompatibility even though the content of PC monomer unit in the copolymer was around 20 mol %, which was confirmed by the platelet adhesion test. Therefore, the introduction of PC group in the side chain of aromatic polyamide was effective to develop the biocompatibility, which would be due to the surface property covered with polar PC units.