Study On Blood Compatibility Of Double Modified Polyvinylidene Fluoride Membrane

Poly(vindene fluoride) (PVDF) membrane is widely used in pervaporation, ultrafiltration, microfiltration due to its excellent good mechanical properties, heat and chemical resistance. However, the hydrophobic PVDF membrane, as filtration media used for protein solvent, may easily absorb proteins resulting in serious fouling and decreasing of permeation flux with time. In addition, the PVDF membrane surface contacting with blood is adhered with a significant amount of blood cells and platelets, which gives rise to the occurrence of thrombosis. Therefore, this work focuses on the surface modification of PVDF membrane to improve its hydrophobicity and anticoagulant from the aspect of molecular design.Poly(N-acryloylmorpholine) (PACMO) has broad characteristics such as high hydrophilicity, low toxicity and good biocompatibility. It is applied to transdermal delivery of active agents, plasma extraction, and surface modification of enzymes and proteins. The PVDF powder products C-C double bonds though alkali treatment in order to graft with ACMO using initiator of azobisisobutyronitrile (AIBN) to synthesize the copolymer of PVDF-g-PACMO. Then the copolymer membrane was prepared by a liquid-liquid phase separation technique. To improve grafting ratio of PACMO for enhancing antifouling property of the membrane, a hydrophilic and non-toxic crosslinking agent of ethylene glycol dimethacrylate (EGDMA) is used in the grafting reaction. The results show that the grafting ratio of PACMO increases from 7.43% to 10.68% after adding the crosslinking agent. And the BSA adsorption amount of membrane decreases from 27.2μg/cm2 to 20.5μg/cm2, which indicates the antipollution excellent of the membrane has been enhanced significantly.Combined with the hydrophilicity of ACMO and the antithrombogenicity of AG, the PVDF membrane is co-modified with ACMO and AG. And then, the anti-protein adsorption property and blood compatibility of the modified membrane are studied. Firstly, PVDF-g-(PACMO-PAA) copolymer is prepared by copolymerization of PVDF, ACMO and acrylic acid (AA). Then, the copolymer of PVDF-g-(PACMO-PAA-g-AG) is prepared by reaction of PVDF-g-(PACMO-PAA) and AG. Finally, the copolymer membrane is obtained. Comparison with pure PVDF membrane, the hydrophilicity of PVDF-g-(PACMO-PAA-g-AG) copolymer membrane has been increased significantly, the protein adsorption amount of the membrane decreases from 118.48μg/cm to 71.97 μg/cm2, the adhesion amount of platelets and red blood cells decreases, and the hemolysis rate also decreases. After adding AG to the reaction system, the hydrophilicity of the modified membrane increases slightly. But the protein adsorption mount, platelets adhesion and red blood cells adhesion mount, and hemolysis rate have been decreased significantly. Moreover, the plasma recalcification time, activated partial thromboplastin time, prothrombin time and thrombin time of the modified membrane have been prolonged significantly, and the fibrinogen concentration has been decreased.