Preparation And Characterization Of Affinity Polymer Carrier Microspheres By Soap-free Emulsion Polymerization

Affinity polymer microsphere is a kind of functional polymer microsphere which has affinity configuration molecules or groups on the particle surface. Because of the large specific surface area, well monodisperse, stable dispersion, excellent bio-compatible capability and easy-separated, affinity polymer microspheres has quite extensive potential applications in the field of biochemistry and medical science. Soap-free emulsion polymerization is extremely advantaged suitable for preparing affinity microsphere used in biomedical field, not only for its little pollution to environment, but also for its effective to control the particle's size, conformation and surface properties.The preparation and characterization of affinity polymer microspheres with different functional groups has been studied in this paper. Soap-free emulsion copolymerizations of hydrophobicity monomer styrene (St) with hydrophilic monomer glycidyl methacrylate (GMA) or hydroxyethyl methacrylate (EHA) or methacrylic acid (MAA) were separately carried out. The preparation processes and functional methods of the affinity polymer microsphers were studied theoretically and experimentally.The first chapter mainly introduced the domestic and international research progress on affinity polymer microsphere, elucidated the microsphere's synthetic design principles, carrier microspheres' preparation and characterization and the immobility method of bioactive substance molecules, and summarized their applications in the areas of bioseparation, DNA diagnosis, drug carrier and so on. In addition, the nucleation theory, prepare methods and influencing factor of soap-free emulsion polymerization were also briefly introduced. Then the purpose of this research was indicated.The second chapter summed up the experiments of this paper, listed the main raw material and equipments used in experiments, described operation method ofP(St-GMA), P(St-EHA), P(St-MAA) carrier microspheres' preparation and novel spacer's synthesis and grafting, then introduced the characterization methods for soap-free emulsion copolymerization kinetics and microspheres' performance such as stability, particle size and distribution, appearance, functional group concentration and so on.The third chapter discussed the experimental results. The curves of conversion to time at different reaction temperature (T) and initiator concentration ([KPS]) were investigated to evaluate the kinetics rule of soap-free emulsion copolymerization. The results showed that average polymerization rate (AV) is exponential to the concentration of initiator ([KPS]). The effects of polymerization factors such as monomer ratio, initiator concentration and pH on latex performance and functional group distribution were examined. The experimental best result i.e. stable and monodisperse P(St-GMA) microspheres (particle size about 300nm, distribution factor<1.06) with surface epoxy values 0.009mol/100g could be prepared by batch-fed method with functional comonomer (GMA) content 33.3wt% initiator content 3.3wt% at 75℃ which was the optimum condition for PSG microspheres.Novel spacers NH₂(PEO)NH₂ with different chain length were synthesized, and the process conditions were optimized. The synthesis and grafting of spacer were analyzed with elemental analysis and FTIR. The determined results of spacers with different carbon chain length grafting on PSG microspheres showed that the novel spacer NH₂(PEO)NH₂ had better grafting effection than 1,6-hexanediamine. Thus, NH₂(PEO)NH₂ is more suitable to be the spacer of affinity polymer microspheres.The microsphere's appearance, particle size and distribution were observed with transmission electron microscope (TEM), scanning electron microscope (SEM) and laser sizer device (DLS). The available values of epoxy, carboxyl and hgydroxy groups on the surface of microspheres were separately determined by pyridine-HCl, Hen conductance and acid-base titration. Consequently, a set of characterization methods for affinity polymer microspheres' performance were established. The fourth chapter summed up the total research work.