Synthesis And Characterization Of Surface Modifier Of Polypropylene

Due to its low surface energy and relatively high crystallinity, products of polypropylene are hard to dye, adhere and coat. Its compatibility with polar polymers is also poor. As a medical polymer material, the non-polar structure of polypropylene is far different from the structure of organisms', which causes the phenomenon of rejection when it contacts with the wounds. In addition, the material surface should avoid bacterial or fungal infections and the spread of disease, as well as to avoid the occurrence of electrostatic hazards in the application of polypropylene. To overcome these barriers,surface modification is frequently employed to enhance its surface performances.By introducing functional segments onto the surface, the biocompatibility, antibacterial and antistatic properties of polypropylene can be improved. Meanwhile, new surface performances of polypropylene can be achieved by introducing functional segments onto the surface, which can expand the scope of its application.Blending with macromolecular surface modifiers is often recognized as a potential technique to functionalize the surface of polypropylene. Modification by loading with macromolecular surface modifiers at very low content has a significant effect on the surface performance without affecting its ontology. Furthermore, compared with the low molecular weight surfactants, macromolecular surface modifiers are more difficult to be detracted from the surface when the products are frictionized or washed with water and organic solvents, which endows their lasting effectiveness.The aims of this dissertation are to synthesize the block copolymers suitable for surface modification of polypropylene and to evaluate the preferential segregation of additives on the surface of polypropylene blends. PP-b-PVP, as well as PP-b-PBS and PP-b-PHB used were synthesized through the esterification of dicarboxyl-terminated polypropylene with hydroxyl-terminated respective polymers. Their structures and thermal stabilities were characterized by IR, NMR and TGA. The surface enrichments of copolymers on polypropylene were evaluated by attenuated total reflectance IR Spectroscopy, contact angle measurements. The modified effects of biocompatibility were also characterized by determination of the extent of platelet adsorption, plasma recalcixcation time and hemolysis rate, cell proliferation using smooth muscle cells from rabbit aorta. The results revealed that the blood compatibility and cell compatibility of PP are improved significantly by entrapment of a few copolymers in PP.In addition, PP-b-PQVP was synthesized and used as a macromolecular surface modifier of polypropylene to enhance its surface antimicrobial and anti-electrostatic properties. The results of ATR-FTIR, contact angle measurement indicated that the additive can enrich on the surface of polypropylene and increase its antibacterial activity and anti-electrostatic property.The modifying durability was studied by the solvent-soaked experiments. Compared with the small molecule modifiers, the macromolecular surface modifiers exhibit better stability of resistant-solvent.