Preparation Of Double Modified PVDF Membrane And Its Blood Compatibility Study

Poly(vinylidene fluoride)(PVDF)has been widely used in the field of in the field of wastewater treatment,artificial blood vessel,tissue engineering because of its excellent thermal stability,chemical stability and mechanical strength.However,PVDF membrane is easy to adsorb blood plasma protein and blood cells,triggering coagulation,hemolysis and other immune responses due to its strong hydrophobicity and low surface energy.These disadvantageous limit its application in the field of blood contact materials.In this study,In order to overcome the above mentioned shortcomings of the single hydrophilization or heparinize modified method for blood contact membrane material,we introduced hydrophilic poly(N-acryloylmorpholine)(PACMO),2-acrylamido-2-methylpropanesulfonic acid(AMPS)and anti-clotting agent AG,synchronously.PVDF powder was modified ACMO and AMPS by the method of the free-radical polymerization in solution,and the copolymers were characterized byfourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance proton(1H-NMR).PACMO was introduced to improve the hydrophilicity and biocompatibility of the modified membranes,and PAMPS was used to imitate the molecular structure and anti-coagulation property of heparin.The membranes were prepared via immersion phase inversion.The result of X-ray photoelectron spectroscopy(XPS)proves the surface macrosegregation of the hydrophilicity segment such as PACMO and PAMPS.The SEM analysis result of the dual modified membrane shows the hydrophilic segments of PACMO and PAMPS can act as the poring-agent.After dual modification,the water contact angle of the membrane decreases from 91.8° to 75.2°,which indicates the hydrophilicity of the dual modified membrane is improved.The blood compatibility of membranes was characterized though blood cell adhesion and coagulation time.Few of platelets or red blood cells adhere on the surface of the dual modified membrane.Contrasted with pure PVDF membrane,activated partial thromboplastin time(APTT)and prothrombin time(PT)of the dual modified membrane were prolonged by 7.80 s and 2.83 s,respectively.The results show that the anti-coagulation property of the dual modified membrane is enhanced.Argatroban is a small molecule direct thrombin inhibitor.its anti clotting mechanism is different with heparin or heparin,The anti coagulation process of AG does not require antithrombin.PVDF-g-PACMO and PVDF-g-PAA polymers were prepared via free radical polymerization.And then AG was grafted onto the PVDF-g-PAA polymer via amide reaction.The PVDF-g-PACMO,PVDF-g-PAA and PVDF-g-(PAA-AG)polymer structures were characterized by FT-IR and 1H-NMR.Then,the PVDF-g-PACMO and PVDF-g-(PAA-AG)polymers were blended in a certain proportion and the membrane was prepared by immersion phase inversion method.The result XPS proves the surface macrosegregation of the hydrophilicity segment such as PACMO and AG.The SEM analysis result of the dual modified membrane shows the hydrophilic segments of PACMO and PAA can act as the poring-agent.The initial contact angle of the modified membrane was decreased from 91.8° to 72.1°.The M-1:3 membrane greatly inhibited the protein(reduced by 90%)and the adhesion of blood cells.Compared with pure PVDF membrane,APTT and PT were extended by 86.7 s and 14.5 s,separately.The FIB decreased from 1.981 g/L to 1.743 g/L.All results indicate the coupling of PACMO,PAA and AG have not only endowed the dual modified membrane with well hydrophilicity,but also with excellent blood compatibility.