Preparation Of Composite Microspheres Based On SMA And Their Application In Dye Adsorption And Sustained Drug Releasing

Chitosan (CS), poly D-glucosamine, is the deacetylated form of chitin whose natural abundance is second only to cellulose in natural organic compounds. It has been found that CS has good biocompatible and biodegradable properties. Poly(styrene-alt-maleic anhydride) (SMA) is a well-known regular alternating combination of styrene (St) and reactive maleic anhydride (MA) in its linear molecular chain copolymer with low toxicity, low cost, and good biocompatibility and biodegradation. It has been widely used in the fields of waste water treatment agent, bionic microreactor and biological medicine, etc. In this paper, sulfonated poly(styrene-alt-maleic anhydride) (SSMA) microspheres were prepared from SMA by sulfonation reaction and its adsorption behavior as an efficient adsorbent for the removal of organic dyes was systematically studied. The obtained SSMA microspheres were etched to form a hollow bowl-like structure by nonsolvent/solvent-induced phase separation (N/SIPS) method. Then, CS was used as covered shell to coat onto the surface of SMA to get SSMA8h/CS composite microspheres.At last, hollow structured SSMAgh/CS@Fe3O4 was prepared and the drug loading and sustained-releasing properties for simulated drug were also studied. The main contents and conclusions of this paper are as follows:1. SMA spheres were prepared via precipitation polymerization method. Then, the as-prepared SMA microspheres were coated with sulfonic acid group by sulfonation with sulfuric acid as surface modification agent. The obtained SMA and SSMA microspheres were etched to form a hollow structure by nonsolvent/solvent-induced phase separation (N/SIPS) method. The effects of the variety of solvent, monomer concentration, etching agent’ type and dosage and the sulfonation time on microspheres’ morphology and structure were investigated. Results showed that expected regular alternating SMA microspheres were obtained if choosing ethyl butyrate as solvent, monomer concentration of 0.5 mol/L. When the sulfonation time was 5-8 h, the SSMA microspheres were etched to be hollow structure with volume ratio 17:10:2:1 of etching agents (water/butanol/n-heptane/tetrahydrofuran).2.SSMA was prepared from SMA by sulfonation reaction and its adsorption behavior as an efficient adsorbent for the removal of organic dyes was systematically studied. SMA/CS and SSMA8h/CS composite microspheres were prepared by in situ reaction. The structure and morphology of SMA、SSMA、SMA/CS and SSMA8h/CS were characterized by FT-IR、XPS、TEM、SEM、EDX.Methylene blue (MB) and Rhodamine B (RhB) were selected as two typical cationic dyes, while Methyl Orange (MO) and Congo Red (CR) selected as anionic dyes. The adsorption performance of SMA, SSMA, SMA/CS and SSMA8h/CS toward organic dyes was investigated by batch mode adsorption experiments. Results indicated that SMA and SSMA could be used for efficiently removal cationic dyes from aqueous solutions such as MB and RhB.The adsorption capacity for MB of SSMA8h which had been sulfonated 8 h was found to be 671.14 mg/g, while the adsorption capacity of SMA for MB was 344.83 mg/g at 25℃, showing that the adsorption capacity for cationic dyes was enhanced 94.63% via the sulfonation. The kinetic studies revealed that the sorption followed a pseudo-second-order kinetic model which indicated that the adsorption interaction between adsorbent and adsorbate molecules was chemisorption. The equilibrium data was well fitted to the Langmuir isotherm model, indicating that the adsorption was a monolayer-adsorption process and mainly controlled by electrostatic interaction between negative polarity adsorbent and cationic adsorbate.3.In order to further improve the environmental responsiveness of the hollow structured SSMA8h/CS, SSMA.8h/CS@Fe3O4 microspheres were prepared through the introducing of Fe3O4. Taking ibuprofen (IBU) and soldium salicylate as model drugs, the controlled release behavior of the SSMA8h/CS@Fe3O4 microspheres was investigated. Results showed that SSMA8h/CS@Fe3O4 microspheres were synthesized successfully. And they could be easily separated and collected under magnetic field, indicating that they had good magnetic responsiveness. However, the drug loading and sustained-releasing experiment results were not desired. The possible reasons for the results was that we chose the commonly used ibuprofen and sodium salicylate as model drugs according to the literature which were both anionic, they might be difficult to load on SSMA8h/CS@Fe3O4 hollow microspheres due to the repulsion between charges of anionic drugs and anionic drug carrier.