Study On Synthesis Of Poly(Styrene-co-Maleic Anhydride) And Their Functionalization For Membranes And Microspheres

Poly(styrene-co-maaleic anhydride) is one of important polymers, and has been studied for decades. Copolymerization of styrene with maleic anhydride can result in alternative copolymer, easily used for farther functional design. It will extend the application fields of polymer materials. The former studies on the copolymer of styrene and maleic anhydride mainly focused on the copolymerization mechanism and copolymer structure, and few studies on the synthesis of alternative copolymer with high molecular mass and functional design of the copolymer were reported rarely. In this paper, synthesis of high molecular mass copolymer and functional design were emphasized, especially for membrane separation, magnetic and fluorescent susceptibility and biological activity. A ultra high molecular mass poly(styrene-alt-maleic anhydride)(SMA) was synthesized by the copolymerization of styrene and maleic anhydride in the supercritical carbon dioxide, which blended with poly(vinylidene fluoride)(PVDF) to prepare the SMA/PVDF alloy membrane by immersion precipitation. The SMA-modified PVDF microporous membrane was prepared by the copolymerization of styrene with maleic anhydride on the surface of PVDF membrane, and furthermore used for immobilization of β-galactosidase. In addition, Fe₃O₄/SMA composite microspheres were synthesized by copolymerization of styrene with maleic anhydride in the magnetite particles as seeds, used for immobilization of α -amylase. Fluorescent magnetic composite microspheres of SMA, for immobilization of heparin, were prepared by incorporated into the SMA microspheres. The experiment methods and results are summarized as follows.Radical copolymerization of styrene (St) and maleic anhydride (Man) was performed in supercritical carbon dioxide (SCCO₂) at 50-80°C with 2,2'-azoisobutyronitrile as the initiator. A novel, ultra-high molecular mass St-Man alternative copolymers (Mw > 10⁶) has been synthesized. The NMR spectra demonstrated that the copolymers obtained possess strictly alternating structure. Aqueous solutions of the alternative copolymers exhibit lower critical solution temperatures (LCST). These LCST's are highly sensitive to changes in the molecular weight and pH. St/MAn copolymerization in SCCO2 as the solvent yieldedhigher molecular weight products and more cis configuration linkage of cyclic MAn units in the copolymer chains than those made in common organic solvents. These facts demonstrate that SCCO2 as the solvent play an important role in the copolymerization of styrene with maleic anhydride, originating from the special intermolecular interactions between SCCO2 and St-Man alternative copolymer.Miscibility of poly(vinylidene fluoride) (PVDF) with poly(styrene-co-maleic anhydride) (SMA) copolymers was explored. SMA/PVDF polymer alloy membrane was prepared by immersion precipitation from the PVDF blends with SMA copolymers. The effects of SMA/PVDF ratio on membrane structure was studied. The microporous membranes were formed from the blends of SMA and PVDF when SMA content of the blends was below 50 wt%, and otherwise, the dense membranes resulted from the SMA/PVDF blends of higher than 50% SMA. Membranes for the ultrafiltration process were prepared from SMA/PVDF blends with SMA content of lower than 50 wt%. The porous size of SMA/PVDF microporous membranes decreased with increasing the SMA content of the blends. The membranes prepared from the blends of PVDF and SMA exhibited higher water flux than the membranes prepared from PVDF without any loss in solute rejection. The hydrophilicity and anti-fouling property of the SMA/PVDF polymer alloy membranes were improved due to SMA on the surface of the membrane, estimated by contact angle and BSA adsorption.Surface modification of poly(vinylidene fluoride) (PVDF) microporous membrane via thermally induced graft copolymerization with maleic anhydride (Man) / styrene (St) in supercritical carbon dioxide (SC CO2) system was carried out. The alternative copolymer segments of Man-alt-St (SMA) were grafted onto the membrane surface and within membrane pores to obtain the SMA-based PVDF membrane. The surface microstructure and composition of the SMA-based PVDF membranes were characterized by FT-IR/ATR, X-ray photoelectron spectroscopy (XPS), Solid-State 13C CP/MAS NMR, differential scanning calorimetric analysis (DSC), and scanning electron microscopy (SEM). In general, the graft concentration of SMA increased with the increase of Man/St comonomer concentration and reaction temperature and decrease of SC CO2 pressure used for graftcopolymerization. FT-IR/ATR and XPS analyses of the modified membranes revealed that the SMA grafting degree decreased gradually from the obverse side to ulterior side. The alternative structure of the grafted SMA was confirmed by CP/MAS NMR. The hydrophilicity and biocompatibility of the modified membranes was studied by pure-water contact angle, protein adsorption measurements, and cell growth assay. The modification by SMA grafting made static contact angle of pure water, and protein adsorption on the modified membrane decreased significantly, related with excellent hydrophilicity of the SMA-based membrane. However, SMA-based membrane behaved preferable cell proliferation for CE cell growth after a given time of incubation.The SMA modified PVDF membrane were prepared by the copolymerization of styrene with maleic anhydride on the surface of PVDF membrane in the supercritical carbon dioxide. Free P-galactosidase was immobilized on the membranes by the formation of amido bonds between the amino groups of the enzyme and the anhydrides on the surface of the membranes. The effects of immobilization on the properties of the immobilized P-galactosidase were studied. The immobilized membrane showed the highest activity when P-galactosidase was immobilized for 6h under the condition of pH 8.2, 4°C, and enzyme/membrane 1:10. The activity of immobilized enzyme and protein binding capacity reached 13.5U and 68.2ug/cm2 membrane. The specific activity of immobilized enzyme could reached 280.0U/mg protein. The relative activity was 89.0%, compared with the free P-galactosidase. The immobilized enzyme had higher optimum temperature and pH compared with that of free P-galactosidase and showed excellent operational and storage stability.Fe3O4/poly(styrene-co-maleic anhydride) core-shell composite microspheres suitable for binding enzymes were prepared using magnetite particles as seeds by copolymerization of styrene and maleic anhydride. The magnetite particles were wrapped up by polyethylene glycol, which improved the affinity between the magnetite particles and the monomers. It shows that the size of the microspheres , the amount of the surface anhydrides and the magnetite content in the composite are highly dependent on magnetite particles, comonomer ratio and dispersion medium used in the polymerization. Thecomposite microspheres, having 0.08-0.8 //m diameter and containing 100-800 u g magnetite/g microsphere and 0¹8mmol surface-anhydride groups/g microsphere have been obtained. Free a -amylase was immobilized on the microspheres containing reactive surface-anhydride groups by covalent binding. The effects of immobilization on the properties of the immobilized a -amylase (MIE) were studied. The activity of MIE and protein binding capacity reached 113,800U and 544.3mg per gram dry microspheres. The activity recovery was 47.2%.The MIE had higher optimum temperature and pH compared with that of free a -amylase and showed excellent thermal, storage, pH, and operational stability. Furthermore, It can be easily separated in a magnetic field and reused repeatedly.A fluorescence magnetic composite poly(styrene-maleic anhydride) microsphere, suitable for conjugation with glycopolymer, were synthesized using magnetite/europium phthalate particles as seeds by copolymerization of styrene and maleic anhydride. The magnetite/europium phthalate particles were wrapped up by polyethylene glycol, which improved the affinity between the seed particles and the monomers. The composite microspheres obtained, with a diameter of 0.15⁰.7//m contain 586¹013//g magnetite/g microsphere and 0.5-16 mmol surface-anhydride groups/g microsphere. Heparin was conjugated with the reactive surface-anhydride groups on the surface of microspheres by covalent binding to obtain a fluorescence magnetic glycopolymer microsphere. The microspheres not only retain the bioactivities, but also provide magnetic susceptibility and fluorescence. They can be used as a carrier with magnetic orientation and fluorescence tracer for potent drug target. The orientation, tracer and anticoagulation of the fluorescence magnetic glycopolymer microspheres were studied. The anticoagulant activity of the microspheres and heparin binding capacity reached 54,212.8U and 607.lmg per gram of dry microspheres. The activity recovery was 50.2%. The anticoagulant activity of the microspheres increases with the increase of the conjugated heparin on the surface of the microspheres and the decrease of the microsphere size. Furthermore, The fluorescence magnetic glycopolymer microspheres can be easily transported to a given position in a magnetic field and traced via their fluorescence.