Preparation And Properties Of Biodegradable Phosphorylcholine-modified Polyurethane With High Hemocompatibility

Polyurethane?PU?has been widely used in the medical field due to its excellent mechanical properties and good biocompatibility.With the improvement of the requirements for medical materials to reduce the biological reactions,the preparation of polyurethane materials high biocompatibility has become a hot topic at this stage.Phosphorylcholine?PC?,which is a component of the cell membrane,possesses high hemocompatibility due to its strong hydrophilicity produced by equal kation and anion.One of the most effective ways to improve the hemocompatibility of PU is to introduce the PC groups into PU materials.In this paper,phosphorylcholine-modified polyurethane were prepared by physical mixing and chemica l modification.The properties of the modified materials were studied,and the main contents and results are as follows:?1?2-Methacryloyloxyethyl phosphorylcholine?MPC?was synthesized successfully via four steps,and then copolymer?PMEH?of MPC and methacrylate?EHMA?was prepared by free radical polymerization;the biodegradable segmented polyurethane?SPU?with PLA-PEG-PCL as soft segments and HDI-BDO-HDI as unform-size hard segments was prepared by chain extension.The chemical structure of MPC and SPU were characterized by infrared?IR?spectra,¹H nuclear magnetic resonance?¹H NMR?and gel permeation chromatography?GPC?.?2?The composites of SPU and PMEH were prepared using a simple physical mixing method and their potential application as biomaterials was assessed.The SPU and PMEH were dissolved in mixture of C HC l₃ and C H₃OH?volume ratio is 1:1?to get a homogenous solution,then the composite films with different PMEH content were obtained by solvent evaporation method.The influence of PMEH content on the physicochemical properties of the composite films,including thermal properties,mechanical properties,surface and bulk hydrophilicity,and in vitro biodegradability,were researched.The thermal stability studies indicated that the composite films had slightly high thermal stability;the ultimate stress and elongation at break of composite films decreased with the increase of PMEH content;the results of water contact angle and water absorption showed that the surface and bulk hydrophilicity were closely related with the PMEH component.In vitro degradation studies showed that the degradation rate increased with the increasing content of PMEH in composites,indicating that the degradation rate of composite films could be controlled by adjusting PMEH content.The surface hemocompatibility of the composite films was examined by bovine serum albumin adsorption and platelet adhesion test.It was found that composite films had improved resistance to protein adsorption and possessed good resistance to platelet adhesion.?3?Using a classical Michael addition,MPC was reacted with?-thioglycerol to obtain a phosphorylcholine diol compound?MPC-diol?with two hydroxy at one end.The PC modified SPU?SPU-PC?with PC groups on the side chains were prepared with polycaprolactone diol?PCL,M_n=2000?as soft segment,HDI-BDO-HDI diisocyanate as hard segment and MPC-diol as chain extension,and the corresponding films was obtained by solvent evaporation method.The chemical structure was confirmed by IR,¹H NMR and GPC.From the results of X-ray diffraction?XRD?and differential scanning calorimetry?DSC?,it could be found that the degree of the microphase separation degree was enhanced with the increase of hard segment content in SPU-PC,and the results of mechanical properties measure showed that the the ultimate stress and elongation at break of the films decreased with the increasing hard segment content.In vitro degradation studies indicated that SPU-PC films had faster degradation rate than unmodified SPU.The surface hemocompatibility of the films was examined by bovine serum albumin adsorption and platelet adhesion test,ant the result showed that SPU-PC films had lower amount of protein adsorption and platelet adhesion,which meaned excellent hemocompatibility.