| With the rapid development of technology and the health consciousness of human beings, an increasing number of people realized the importance of biomedical materials, and application standards will be continuously enhanced. As we all know, hemodialysis is an effective method for the treatment of many diseases, such as uremia, renal failure, liver failure, autoimmune disease and acute poisoning. So far, most hemodialysis materials are polymers. Because of its stable physical and chemical properties as well as excellent absorption capacity, polystyrene (PS) has attracted many rsearchers’attention. It is still a great challenge to improve the absorption capacity and biocompatibility of PS resins and to optimize the synthesis technics. In this article, we contributed to the synthesis and biocompatible modification of PS resins. First, we synthesized PS resins with the diameter of0.45～1mm. And then, through both functional group reaction and UV-induced reaction, we successfully grafted biomolecules onto the surface of PS resins by covalent bands, at the same time, optimized reaction conditions and researched their absorption capacity.In chapter1, the development and requirements of biomedical polymeric materials has been reviewed, including the categories of biomedical polymeric materials, the coagulation mechanism, evaluation methods of biocompatible materials and familiar modification approaches. Finally, we presented the design ideas and research content.In chapter2, PS resins grafted poly (ethylene glycole)(PEG) through functional group reaction have been studied. Firstly, we synthesized PS resins with the diameter of0.45～0.1mm through suspension polymerization, and the morphology of PS resins was characterized by scanning electron microscopy (SEM) which presented pores and channels inside and outside clearly. Secondly, maleic anhydride (MA) was grafted onto the surface of PS resins based on thermal induced radical grafting copolymerization of styrene (St) and MA with benzoyl peroxide (BPO) as initiator. After research, we found that with the enhancement of monomers and initiator concentration and reaction time (2h～6h), grafting rate was improved gradually, and when THF, toluene, paraffin were used as reaction solvents in turn, grafting rate was increased. Finally, we utilized the reaction between anhydride and hydroxyl to graft PEG onto PS resins by covalent band and characterized their structures both before and after modification by FTIR and XPS.The signals of anhydride at1783cm-1and ether at1110cm-1are clearly observed which indicated the presence of MA structure and PEG line on the spheres separately. We also discussed the influence of grafting rate and PEG molecular weight on absorption capacity of resin spheres. With the improvement of grafting rate, PS resins grafted PEG1000showed an increase and then a decrease of absorption capacity which has been decreased when grafted PEG2000. And absorption capacity of resins grafted PEG1000was higher than that of resins grafted PEG2000.In chapter3, PS resins grafted poly (2-hydroxyethyl methacrylate)(PHEMA) through both one-step and two-steps UV-induced radical polymerizations have been studied. We altered the reaction conditions, such as the concentration of monomer and initiator, the volume of photosensitiser and the reaction time, to optimize the synthesis technics. Compared with one-step method, two-steps method showed higher grafting rate with lower reaction conditions (monomer and initiator concentration decreased from200g/L and100g/L to3g/L and0.02g/L respectively), which made the decrease of costs come ture. Molecule structures both before and after modification were characterized by FTIR and XPS.The signals of carbonyl at1723cm-1can be observed clearly and indicates the presence of PHEMA on the spheres. With the increase of the grafting rate, there was an enhancement of oxygen content on the surface of resins (demonstrated by XPS analysis) and absorption capacity decreased gradually, although PHEMA contributed to the enhancement of absorption capacity of PS resins.In chapter4, PS resins grafted PEG through two-steps UV-induced radical polymerization have been studied. At first, PEG modified double bond was gathered through reaction between methacryloyl chloride and poly (ethylene glycol) monomethyl ether and then grafted the activated PEG onto PS resins by UV-indeuced polymerization. We altered the reaction conditions, like the concentration of monomer and initiator and the reaction time, to optimize synthesis technics. Molecule structures both before and after modification were characterized by FTIR and XPS. The signals of ether at1110cm-1can be observed clearly and indicates the presence of PEG on PS resin spheres. With the improvement of the grafting rate, PS resins grafted PEG2000showed an increase of absorption capacity which has been increased first and then decreased when grafted PEG750. And absorption capacity of resins grafted PEG2000was higher than that of resins grafted PEG750.In summary, we successfully synthesized biocompatible PS resins through several methods, which also can be used for the further modification of PS resins by biomolecules. |
