Magnetic Polymer Microspheres Research Articles

Fast fabrication of epoxy-functionalized magnetic polymer core-shell microspheres using glycidyl methacrylate as monomer via photo-initiated miniemulsion polymerization

Epoxy-functionalized magnetic polymer microspheres with high magnetic responsiveness were prepared through a one-step photo-initiated miniemulsion polymerization. This kind of core-shell particle can be synthesized successfully with hydrophilic monomer, glycidyl methacrylate, as a single monomer by a 10min ultraviolet irradiation, and phase separation induced eccentric cores. The morphology of the particles was examined with a transmission electron microscope and a scanning electron microscope. The incorporation of magnetic particles was characterized with X-ray diffraction. The magnetic content of the microspheres was detected by both vibrating sample magnetometer and thermo-gravimetric analyzer.

Preparation and characterization of composite microspheres of nano zinc ferrite/poly (D, L-lactide-co-alanine)

Magnetic nano zinc ferrite fliuds were synthesized using an improved liquid phase chemical method, which would be used to replace tradditional iron oxides magnetic material. A novel copolymer (PLAA) with D, L-lactide (D, L-LA) and alanine was synthesized using stannous octoate as initiator. Magnetic polymer microspheres were fabricated with nano zinc ferrite fluid coated with alanine modified poly lactide. These as-prepared zinc ferrite fluids, modified poly lactide and magnetic composites, were characterized with X-ray diffraction diffractometer, FT-IR spectrometer, nuclear magnetic resonance spectrometer, scanning electron microscope, transmission electron microscope, vibrating sample magnetometer, and thermogravimetric analyzer. The results demonstrate that the as-prepared zinc ferrite is spinel type of ZnFe2O4 nano crystals with particle size of 20–45 nm and magnetization of 32×10−3 A·m2. Alanine is copolymerized with lactide, and the prepared composite magnetic microsphere is coated with the modified polylactide, with mass fraction of 45.5% of PLA, particle size ranging from 80–300 nm, and magnetization of 10.6×10−3 A·m2, which suggests ZnFe2O4 enjoys a stable magnetization after being coated by polymer.

Micron-sized Magnetic Polymer Microspheres for Adsorption and Separation of Cr(VI) from Aqueous Solution

The magnetic poly-(methacrylate-divinyl benzene) microspheres with micron size were synthesized by modified suspension polymerization method. Adsorption of Cr(VI) from aqueous solution by magnetic poly-(MA-DVB) microspheres with surface amination was investigated. The adsorption processes were carried out under diversified conditions of pH value, adsorption time and temperature to evaluate the performance of the magnetic microspheres. The optimum pH value for Cr(VI) adsorption was found as 3. The adsorption capacity increased with adsorption time and attained an optimum at 60 min. The adsorption processes for magnetic microspheres was endothermic reaction, and the adsorption capacity increased with increasing temperature.

Comparative Study in Magnetic Composites with PMMA and PS Matrices Made by Suspension Polymerization

Magnetic polymer composites were synthesized via suspension polymerization method, incorporating nanoFe3O4powder into poly (methyl methacrylate) (PMMA) and polystyrene (PS) matrices in order to obtain polymer magnetic microspheres with perspectives in sensing applications. The monomer (MMA or Styrene) and the magnetic powder (pre-made Fe3O4, 20nm in diameter) are mixed together under vigorous stirring and follows suspension polymerization. The product was sequentially filtered through a range of sieves and spherical composites were obtained with grains of sizes ranging from 45μm to 250μm. The yield of polymerization was 60% to 85% for the two different matrices in samples and the corresponding polymer product contained 1.25wt% to 4.00wt% of Fe3O4. It is observed that increasing the content of magnetite affect the surface morphology of the microspheres and their magnetic behavior. The pure nanoFe3O4powder and the magnetic polymer microspheres were characterized using techniques such as X-Ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy and magnetization measurements carried out by a Vibrating Sample Magnetometer (VSM) .

Preparation and Characterization of a New Type of Magnetic Polymer Micro Spheres

A new type of magnetic polymer microspheres with super paramagnetic properties were prepared by a co-precipitation method. Atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscopy (SEM) were used to analyze Fe content, micro morphology, particle size and phase structure of the products. Results indicate that the content of Fe in the microspheres is up to 5.25 *105ug/g. The main phase of the product is Fe3O4. The average particle sizes of the products are ~30nm.

Hydrophilic dual‐responsive magnetite/PMAA core/shell microspheres with high magnetic susceptibility and ph sensitivity via distillation‐precipitation polymerization

AbstractA facile and effective approach to preparation of dual‐responsive magnetic core/shell composite microspheres is reported. The magnetite(Fe3O4)/poly(methacrylic acid) (PMAA) composite microspheres were synthesized through encapsulating γ‐methacryloxypropyltrimethoxysilane (MPS)‐modified magnetite colloid nanocrystal clusters (MCNCs) with crosslinked PMAA shell. First, the 200‐nm‐sized MCNCs were fabricated through solvothermal reaction, and then the MCNCs were modified with MPS to form active vinyl groups on the surface of MCNCs, and finally, a pH‐responsive shell of PMAA was coated onto the surface of MCNCs by distillation‐precipitation polymerization. The transmission electron microscopy (TEM) and vibrating sample magnetometer characterization showed that the obtained composite microspheres had well‐defined core/shell structure and high saturation magnetization value (35 emu/g). The experimental results indicated that the thickness and degree of crosslinking of PMAA shell could be well‐controlled. The pH‐induced change in size exhibited by the core/shell microspheres reflected the PMAA shell contained large amount of carboxyl groups. The carboxyl groups and high saturation magnetization make these microspheres have a great potential in biomolecule separation and drug carriers. Moreover, we also demonstrated that other magnetic polymeric microspheres, such as Fe3O4/PAA, Fe3O4/PAM, and Fe3O4/PNIPAM, could be synthesized by this approach. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.

Preparation of Anti-CD40 Antibody Modified Magnetic PCL-PEG-PCL Microspheres

Antibody modified magnetic polymeric microspheres have potential biomedical application. In this paper, anti-CD40 antibody modified magnetic poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL, PCEC) microspheres were prepared. First, PCL-PEG-PCL triblock copolymer was synthesized by ring-opening polymerization, followed by reaction with succinic anhydride, creating carboxylated PCL-PEG-PCL copolymer. Then, magnetite nanoparticles were encapsulated into carboxylated PCL-PEG-PCL microspheres, forming magnetic PCL-PEG-PCL microspheres with carboxyl group on their surface. Catalyzed by EDC/NHS, the anti-CD40 antibody was linked to these magnetic PCL-PEG-PCL microspheres, thus forming anti-CD40 modified PCL-PEG-PCL microspheres. These anti-CD40 antibody modified magnetic PCL-PEG-PCL microspheres may have potential application in cell separation.

Polycarbonate microspheres containing mitomycin C and magnetic powders as potential hepatic carcinoma therapeutics

The polycarbonate copolymer poly(trimethylene carbonate-co-5,5-dimethyl trimethylene carbonate) (P(TMC-co-DTC)) was synthesized by the polymerization of trimethylene carbonate (TMC) and 5,5-dimethyl trimethylene carbonate (DTC) using tin (II) 2-ethylhexanoate [Sn(Oct)(2)] as a catalyst. In vitro degradation tests indicated this polycarbonate copolymer degraded slowly in phosphate buffer saline solution (PBS, 0.1 mol/L, at 37°C). Magnetic polymer microspheres (MMC-PC-M) generated from the P(TMC-co-DTC) copolymer and containing Fe(3)O(4) magnetic ultrafine powders and an anticancer drug, mitomycin C (MMC) were prepared by a solvent evaporation technique. These anticancer magnetic polycarbonate microspheres showed strong magnetic responsiveness and high MMC loading capacity. In vitro drug release studies indicated that these microspheres sustained steady release rates of MMC in PBS. In vitro cytotoxicity assays demonstrated the microspheres were strongly inhibitory to human hepatic carcinoma (Bel-7204) cells. In vivo site-specific therapy in nude mice with human hepatic carcinoma indicated that the microspheres possessed markedly high antitumor activity against human hepatic carcinoma (Bel-7204).

Magnetic polymer microsphere stabilized gold nanocolloids as a facilely recoverable catalyst

Magnetically responsive hierarchical magnetite/silica/poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (Fe3O4/SiO2/P(EGDMA-co-VPy)) tri-layer microspheres were used as stabilizers for gold metallic nanocolloids as a facilely recoverable catalyst with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The magnetic microsphere stabilized gold metallic nanocolloids were prepared by in situ reduction of gold chloride trihydrate with borohydride as reductant via the stabilization effect of the pyridyl groups to gold nanoparticles on the surface of the outer shell-layer of the inorganic/polymer tri-layer microspheres.

Chemical Mechanical Polishing Using Magnetic Composite Abrasives Slurry and Experimental Study on Polishing Performance

A polishing method that uses an auxiliary magnetic field is proposed,in which magnetic polymer microspheres/SiO2 composite abrasives are anchored on a smooth glass tool plate by the magnetic force,and the dependence between diameter of composite abrasive and morphology of tool plate is reduced.The auxiliary magnetic field is established by NdFeB permanent magnets with 8 mm diameter and different heights.The finite element method(FEM) analysis shows that the magnetic field with a concave-down columnar section has a uniform distribution of the force of magnetic field HdH/dz.Force analyses on magnetic polymer microspheres indicate that the magnetic force could help the magnetic polymer microspheres enter the polishing area from near-polishing area,and material is polished by magnetic composite abrasives in two-body abrasion wear mechanism.Experiments of polishing silica wafer,using a glass tool plate of Ra 0.5 μm surface roughness,have shown the superior characteristics with the assistance of the magnetic field.The material removal rate is increased from 66 nm/min to 179 nm/min,and the surface roughness of wafer is decreased from Ra 405.860 nm to Ra 0.490 nm.

ChemInform Abstract: Synthesis of Magnetic Polymeric Microspheres

AbstractReview: 117 refs.

Preparation of Magnetic Microspheres Based on Poly(<I>ε</I>-Caprolactone)-Poly(Ethylene Glycol)Poly(<I>ε</I>-Caprolactone) Copolymers by Modified Solvent Diffusion Method

Magnetic microspheres have promising application in biomedical field. In this paper, biodegradable poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCEC) triblock copolymers were synthesized by ring-opening polymerization method. Through adjusting the epsilon-CL/PEG weight ratio in feed, PCEC copolymers with different block ratio were obtained. A novel modified solvent diffusion method was described to prepare magnetic PCEC composite microspheres containing magnetite nanoparticles. The particle size of microsphere decreased with increase in the PEG/PCL block ratio. The obtained microspheres could response to external magnetic field. This study described a novel method to prepare magnetic microspheres. The obtained magnetic polymeric microspheres might have potential application in drug delivery system or disease diagnosis field.

An efficient synthesis of ampicillin on magnetically separable immobilized penicillin G acylase

Penicillin G acylase (PGA) was immobilized on the magnetic hydrophilic polymer microspheres with average pore size of 17.1 nm, specific surface area of 128.2 m 2/g and saturate magnetization of 6.4 emu/g. The 96.7% ampicillin yield with 1.60 of the synthesis/hydrolysis (S/H) ratio from 6-aminopenicillanic acid (6-APA) and d-(−)-alpha-phenylglycine methyl ester ( d-PGME) can be achieved using the resultant magnetic biocatalyst in ethylene glycol, where only 82.1% yield with 1.40 of the S/H ratio was obtained using the free PGA under the identical reaction conditions. The immobilized PGA can be separated magnetically and recycled for five times without obvious loss of its catalytic activity.

The Study of Purifying Plasma Thrombin Using Chitosan Affinity Magnetic Microspheres

Nanometer Fe3O4 particle was synthesized by coprecipitation, magnetic polymeric microspheres- magnetic chitosan microspheres, containing a magnetic core and a polymer shell, were prepared by the suspension cross-linking technique. Novel affinity magnetic microspheres were obtained after immobilizing heparin onto the nanoparticles. The size, morphology, structure and magnetic response properties were studied by means of SEM, FT-IR and XRD and so on. The novel affinity magnetic microspheres′ properties for thrombin were examined by its adsorption and purification, and compared with the traditional means of column chromatography— DEAE-Sepharose Fast Flow. The results showed the affinity magnetic microspheres had a spherical appearance, narrow distribution of diameter, the particle diameter is about 50 nm, and one-step purification of thrombin using it the specific activity was 1 879.7 U/mg, recovery rate was 85% and purification fold was 11.057. Whereas, purification of thrombin by column chromatography, the product exhibits an activity of 909.84 U/mg, recovery rate of 72% and purification fold of 5.33. In conclusion, chitosan nanometer affinity magnetic microspheres was prepared and magnetic separation techniques was applied for purification of thrombin, the results is better than that from traditional methods and these results have some references values in the production and subsequent study on the research and development.

PREPARATION AND CHARACTERIZATION OF HYDROPHILIC MAGNETIC POLYMER MICROSPHERES CONTAINING OXIRANES

Spherical hydrophilic magnetic polymer(MGM) containing oxiranes was synthesized by designing the inverse suspension polymerization system in which formamide was employed as the dispersant of magnetic Fe_3O_4 microcrystal.Scanning electron microscopy(SEM),FT-IR spectroscopy,X-ray diffraction(XRD),vibrating sample magnetometer(VSM),low temperature N_2 adsorption and chemical analysis methods were used to characterize the properties of the polymer.The results showed that MGM had good spherical shape and narrow size distribution,and the particles with diameters ranging from 0.13 mm to 0.28 mm were about 91 wt%.The surface hydrophilicity of Fe_3O_4 microcrystal was improved by formamide dispersing treatment.The gel particles made by the copolymerization of glycidyl methacrylate and N,N′methylene bisacrylamide could encapsule Fe_3O_4 microcrystal to produce colloid cores,and uniform and stable MGM microspheres were formed by the conglomeration of the colloid cores.The saturated magnetization of MGM reached 6.5 emu/g while the Fe_3O_4 content were 6.17%.The specific surface area,average pore diameter and pore volume and oxirane content was 117.6 m~2/g,15.6 nm,0.46 cm~3/g and 0.53(mmol/g,)respectively.Penicillin G acylase(PGA) was immobilized on MGM microspheres by the covalent coupling between the reactive oxiranes of MGM and amino groups of PGA under mild conditions.The apparent activity of the immobilized PGA reached 502 IU/g for hydrolyzing penicillin G potassium to 6-aminopenicillanic acid at 37℃.There was no agglomeration of the magnetic particles in applications .

Preparation of Monodisperse Magnetic Polymer Microspheres by Swelling and Thermolysis Technique

A novel process for the preparation of monodisperse magnetic polymer microspheres by uniquely combining swelling and thermolysis technique was reported. The monodisperse polystyrene microspheres were first prepared by dispersion polymerization and swelled in chloroform. Then, ferric oleate was dispersed in chloroform as a precursor and impregnated into the swollen polymer microspheres. Subsequently, the iron oxide nanoparticles were formed within the polymer matrix by thermal decomposition of ferric oleate. The morphology, inner structure, and magnetic properties of the magnetic polymer microspheres were studied with a field emission scanning electron microscope (SEM), transmission electron microscope (TEM), and superconducting quantum interference device (SQUID) magnetometer. The results showed that the average diameter of the magnetic polymer microspheres was 5.1 microm with a standard deviation of 0.106, and the magnetic polymer microspheres with saturation magnetization of 12.6 emu/g exhibited distinct superparamagnetic characteristics at room temperature. More interestingly, the magnetite nanoparticles with a spinel structure are evenly distributed over the whole area of the polymer microspheres. These magnetic polymer microspheres have potential applications in biotechnology.

Facile fabrication of nanocomposite microspheres with polymer cores and magnetic shells by Pickering suspension polymerization

Pickering suspension polymerization was used to prepare magnetic polymer microspheres that have polymer cores enveloped by shells of magnetic nanoparticles. Styrene was emulsified in an aqueous dispersion of Fe 3O 4 nanoparticles using a high shear. The resultant Pickering oil-in-water (o/w) emulsion stabilized solely by magnetic nanoparticles was easily polymerized at 70 °C without stirring. Fe 3O 4 nanoparticles act as effective stabilizers during polymerization and as building blocks for creating the organic–inorganic hybrid nanocomposite after polymerization. The fabricated magnetic nanocomposites were characterized by FTIR, XRD, TGA, DSC, GPC, XPS and SEM. The structures of the polymer core and the nanoparticle shell were analyzed. We investigated the effects on the products of the weight of Fe 3O 4 nanoparticles used to stabilize the original Pickering emulsions. Pickering suspension polymerization provides a new route for the synthesis of a variety of hybrid nanocomposite microspheres with supracolloidal structures.

Synthesis of novel magnetic phosphazene-containing polymer microspheres with active hydroxyl groups

Monodisperse magnetic phosphazene-containing polymer microspheres with active hydroxyl groups were prepared at room temperature by ultrasonic irradiation. The morphology and structure of the magnetic poly(cyclotriphosphazene- co-4,4′-sulfonyldiphenol) (PZS) microspheres were characterized and the coordination behavior between magnetic nanoparticles and PZS microspheres was investigated. The magnetic measurements reveal that the magnetic microspheres are superparamagnetic with saturation magnetization of 34.9 emu/g. The paper presents a simple, economic and environmentally friendly route to preparing monodisperse magnetic hybrid inorganic–organic microspheres with functional groups.

Magnetic polymer microspheres with azidocarbonyl groups: Synthesis, characterization and application in protein immobilization

AbstractA novel magnetic polymer microsphere with amide groups and carboxyl groups was synthesized and reported here. The azidocarbonyl groups were derived from amide groups and linked to the proteins to investigate their immobilization capacity. The morphology, size, functional groups and magnetic properties of magnetic microspheres were characterized by optical microscopy, particle size analyzer, atom force microscopy, magnetic force microscopy, fourier transform infrared spectrometer, vibrating‐sample magnetometer and thermal gravimetric analysis. The results indicated that the magnetic polymer microspheres had a well spherical shape with the size ranging from 1 to 10 μm, highly reactive functional groups, superparamagnetism and strong magnetic responsibility with saturation magnetization of 18.443 emu/g and Fe3O4 content around 21%. The immobilization capacity (η) was over 70%. The novel azidocarbonyl magnetic polymer microspheres showed potentials to be a good magnetic support and promising applications in bioseparation and biomedical fields. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Properties of magnetic poly(glycidyl methacrylate) and poly(N-isopropylacrylamide) microspheres

Iron oxide colloids were prepared by coprecipitation of Fe(II) and Fe(III) salts in alkaline media and stabilized by perchloric acid, oleic acid, or poly(acrylic acid). In an attempt to obtain magnetic polymer microspheres differing in size, dispersion polymerization of glycidyl methacrylate (GMA) in ethanol containing HClO4-stabilized magnetite, dispersion copolymerization of GMA and 2-hydroxyethyl methacrylate (HEMA) in toluene/2-methylpropan-1-ol mixture in the presence of oleic acid-coated magnetite, and inverse suspension copolymerization of N-isopropylacrylamide (NIPAAm) and N,N′-methylenebisacrylamide (MBAAm) in cyclohexane in the presence of poly(acrylic acid)-coated maghemite were compared. The microspheres were characterized by morphology, size, polydispersity, and some magnetic properties.