Preperation And Study Of Phosphocholine Modified Polycarbonate Urethanes

Phosphorylcholine (PC) groups modified polycarbonate polyurethanes (PCUs)were successfully prepared using original surface grafting methods. We used2-methacryloxyethyl phosphorylcholine (MPC) and glycerophosphocholine (GPC)derivatives as the PC groups providing agents. And PC groups were successfullygrafted onto PCU surfaces with MPC based surface coupling method, PCGA basedsurface coupling method and ultraviolet (UV) initiated GPC derivative graftingmethods. XPS analysis, FTIR spectrum and water contact angle measurementsconfirmed the existence of phosphorylcholine groups on the surface of the graftedPCU films. The results of platelet adhesion studies indicated that much fewer plateletsadhered to the surfaces of PCGA grafted PCU films than to the surface of blank PCUfilm. These results indicated that these PC groups grafted PCUs may be used asbiomaterials for blood contacting biomedical devices such as vascular grafts andsubcutaneously implanted devices.The grafting techniques to incorporate PC groups onto PCU surface that havebeen presented in these works have obvious advantages. Firstly, PC groups weregrafted onto PCU surfaces with covalent bonds, so PC groups can remain on thepolymer surface for a long time after incubated in human blood or cell suspension.Consequently, the PC groups on the grafted PCUs can help to resist the adhesion ofblood components on the PCU surfaces for a relatively long period of time. Secondly,the spatial distribution of PC groups on the PC grafting PCUs that prepared by MPCbased surface coupling method and PCGA based surface coupling method is similarto the distribution of PC groups in one of the phospholipids bilayers of human cellmembranes to a certain extent.In addition, we synthesized phase-segregated multiblock copolymers withpolydepsipeptides（alternating copolymers of an α-amino acid and a α-hydroxy acid）and poly(ε-caprolactone)（PCL）segments or poly(p-dioxananone)(PPDO) viacoupling of the respective diols using trimethylhexamethylene diisocyanate ascoupling reagent. Three multiblock copolymers, PCL-PIBMD, PPDO-PBMD andPCL-PMMD, were obtained. We studied thermodynamic properties, biodegradationbehaviors and shape-memory properties of the copolymers. The depsipeptide-basedmultiblock copolymers showed good shape-memory capability and may be used asbiomaterials in different biomedical fields.