Synthesis and Characterization of HDI/MDI-Polycarbonate Urethanes

A novel polycarbonate urethane was synthesized by the two-stage solution process of diisocyanates with polycarbonate diols(PCDL),in which PCDL,1,4-butanediol(BD) and mixture of 4,4 -methylenediphenyl diisocy-anate and hexamethylene diisocyanate(HDI) were soft segment,chain extender and rigid segment,respectively.The structures were characterized by using FTIR and 1H-NMR.The thermoanalysis and mechanical properties of products were measured by means of DSC,TG and other systems.The result shows that an import...

Preparation of phospholipid-based polycarbonate urethanes for potential applications of blood-contacting implants

Polyurethanes are widely used in interventional devices due to the excellent physicochemical property.However,non-specific adhesion and severe inflammatory response of ordinary polyurethanes may lead to severe complications of intravenous devices.Herein,a novel phospholipid-based polycarbonate urethanes(PCUs)were developed via two-step solution polymerization by direct synthesis based on functional raw materials.Furthermore,PCUs were coated on biomedical metal sheets to construct biomimetic anti-fouling surface.The results of stress–strain curves exhibited excellent tensile properties of PCUs films.Differential scanning calorimetry results indicated that the microphase separation of such PCUs polymers could be well regulated by adjusting the formulation of chain extender,leading to different biological response.In vitro blood compatibility tests including bovine serum albumin adsorption,fibrinogen adsorption and denaturation,platelet adhesion and whole-blood experiment showed superior performance in inhibition non-specific adhesion of PCUs samples.Endothelial cells and smooth muscle cells culture tests further revealed a good anti-cell adhesion ability.Finally,animal experiments including ex vivo blood circulation and subcutaneous inflammation animal experiments indicated a strong ability in anti-thrombosis and histocompatibility.These results high light the strong anti-adhesion property of phospholipid-based PCUs films,which may be applied to the blood-contacting implants such as intravenous catheter or antithrombotic surface in the future.

Surface Modification of Polycarbonate Urethane by Covalent Linkage of Heparin with a PEG Spacer

Heparin was grafted onto polycarbonate urethane (PCU) surface via a three-step procedure utilizing α, ωdiamino-poly(ethylene glycol) (APEG, M n =2 000) as a spacer. In the first step, isocyanate functional groups were introduced onto PCU surface by the treatment of hexamethylene diisocyanate (HDI) in the presence of di-n-butyltin dilaurate (DBTDL) as a catalyst. In the second step, APEG was linked to the PCU surface to obtain the APEG conjugated PCU surface (PCU-APEG). In the third step, heparin was covalently coupled with PCU-APEG in the presence of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylamidopropyl) carbodiimide (EDAC). The amount of heparin (1.639 μg/cm 2 ) covalently immobilized on the PCU-APEG surface was determined by the toluidine blue method. The modified surface was characterized by water contact angle, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The hemocompatibility was preliminarily studied by platelet adhesion test. The results indicated that heparin was successfully grafted onto the PCU surface, and meanwhile the hydrophilicity and hemocompatibility of the modified PCU surface were improved significantly compared with the blank PCU surface.

Electrospinning of polycarbonate urethane biomaterials

Polycarbonate urethane(PCU)nano-fibers were fabricated via electrospinning using N,Ndimethylformamide(DMF)and tetrahydrofuran(THF)as the mixed solvent.The effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was investigated.The results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1∶1.When the proportion of DMF was more than 75%in the mixed solvent,it was easy to form many beaded fibers.The applied voltage in the electrospinning process has a significant influence on the morphology of fibers.When the electric voltage was set between 22 and 32 kV,the average diameters of the fibers were found between 420 and 570 nm.Scanning electron microscopy(SEM)images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration.When the concentration of PCU solution was 6.0 wt-%,a beaded-fiber microstructure was obtained.With increasing the concentration of PCU solutions above 6.0 wt-%,beaded fiber decreased and finally disappeared.However,when the PCU concentration was over 14.0 wt-%,the average diameter of fibers became large,closed to 2μm,because of the high solution viscosity.The average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution(10.0 wt-%)when the applied voltagewas 24 kV.The results show that the morphology of PCU fibers could be controlled by electrospinning parameters,such as solution concentration,electric voltage and flow rate.