Preparation and characterization of micron‐sized non‐porous magnetic polymer microspheres with immobilized metal affinity ligands by modified suspension polymerization

A novel preparation method of micron‐sized non‐porous magnetic polymer microspheres with immobilized metal affinity ligands was developed. A modified suspension polymerization of methacrylate (MA) and divinylbenzene (DVB) was performed in the presence of oleic acid‐coated magnetic Fe₃O₄ nanoparticles to obtain magnetic poly (methacrylate‐divinylbenzene) (mPMA‐DVB) microspheres. Through ammonolysis using ethylenediamine (EDA) and subsequent carboxymethylation with chloroacetic acid, magnetic polymer microspheres with chelate ligands of iminodiacetic acid (IDA) were obtained. Charging with copper ions resulted in magnetic polymer microspheres capable of binding proteins that display metal affinity. The morphology, magnetic properties, and composition of magnetic polymer microspheres were characterized with scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR), respectively. Bovine hemoglobin (BHb) was adopted as a model protein to investigate their affinity adsorption capacity. It was found that the adsorption capacity was as high as 168.2 mg/g microspheres and with rather low non‐specific adsorption. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2174–2180, 2005     

High‐molecular‐weight polyurethanes prepared by one‐step miniemulsion polymerization

Through one‐step miniemulsion polymerization, hydrophobic polyurethane (PU) dispersions were prepared, with hexadecane (HD) as costabilizer in the oil phase and sodium dodecyl sulfate (SDS) as surfactant in the water phase. The oil phase, including isophorone diisocyanate, poly(oxytetramethylene) glycol, a costabilizer HD, a chain extender 1,4‐butanediol, a crosslinking agent trimethylol propane, and a catalyst dibutyltin dilaurate (SnDBL), was dispersed in the water phase containing SDS. The influences of experimental parameters, such as SnDBL, NCO/OH equivalents, and concentrations of surfactant, were discussed. The particle size and the molecular weight of PU polymer were measured by light scattering and gel permeation chromatography, respectively. With the addition of SnDBL and higher NCO/OH ratio, PU films with higher molecular weights were produced. The chemical structure of the PU polymer was identified by Fourier transform infrared spectrometer, and the adsorption of urethane group was observed. Thermal gravimetric analysis was used to characterize the thermal stability of PU. Furthermore, mechanical property was also investigated and characterized by tensile strength and elongation at break. With a higher NCO/OH ratio and the existence of SnDBL, the tensile strength of PU films was significantly increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Magnetite‐coated polystyrene hybrid microspheres prepared by miniemulsion polymerization

Hybrid microspheres with a polystyrene core coated with magnetite nanoparticles were prepared by miniemulsion polymerization. Acrylic acid was used as a comonomer to promote the anchoring of the magnetite nanoparticles onto the polymeric surface. The addition of a hydrophobic agent prevents effectively the monomer from diffusing into the aqueous phase. Magnetite was treated with a silane coupling agent in order to introduce some interactions with the polymers. The morphology and the structure of the hybrid microspheres were characterized using X‐ray diffraction, infrared spectroscopy, transmission electron microscopy and thermogravimetric analysis. The results show that the morphology of the hybrid microspheres was influenced by the concentrations of acrylic acid, hydrophobic agent and surfactant, and that the degree of coating can be tuned by changing these parameters. The miniemulsion polymerization technique is adaptable to the synthesis of magnetite‐coated polymer particles, and the synthesis can be scaled up. Copyright © 2008 Society of Chemical Industry     

Preparation and characterization of thermoplastic starch/PLA blends by one‐step reactive extrusion

In the presence of dicumyl peroxide, the compatibility of thermoplastic dry starch (DTPS)/poly(lactic acid) (PLA) blends, using maleic anhydride (MA) as compatibilizer, was investigated. The plasticization of starch and its compatibilizing modification with PLA was accomplished in a single‐screw extruder by one‐step reactive extrusion. In the presence of MA, the plasticization of starch in DTPS/PLA blends could be improved and homogeneous DTPS/PLA blends could be achieved as observed using scanning electron microscopy. Tensile tests showed that the tensile strength of compatibilized DTPS/PLA blends was about 40.5 MPa higher than that of the original composites. Differential thermal analysis indicated that the glass transition temperature of DTPS and PLA became closer in the presence of MA than the blend without any additions, which suggested the compatibility between DTPS and PLA was improved. In addition, Fourier transform infrared spectroscopy proved that MA improved the interaction between DTPS and PLA. At the same time, the blend became more thermally stable as shown by thermogravimetric analysis results. A novel decomposition peak at about 450 °C was detected in the compatibilized blend, which was higher than those observed for DTPS and PLA. Finally, a rheological study suggested that MA could improve the fluidity of DTPS/PLA blends. Copyright © 2007 Society of Chemical Industry     

Preparation and characterization of imidazole‐functionalized microspheres

The preparation of imidazole‐functionalized latex microspheres by a two‐stage emulsion copolymerization process and their characterization are reported on. Emulsifier‐free emulsion copolymerization of styrene (St) and 1‐vinyl imidazole (VIMZ) exhibited bimodal particle size distributions caused by secondary homogeneous nucleation process. However, secondary nucleation can be avoided by using cetyltrimethylammonium bromide (CTAB) as a stabilizer at a concentration below its cmc (critical micelle concentration). This would result in the formation of monodisperse latex particles. The final particle size diameter depended on the concentration of CTAB as well as the amount of VIMZ. To control the amount of the functional imidazole groups on the latex particle surfaces, independent of the latex diameters, without secondary nucleation of particles, the seeded emulsion copolymerization of styrene and VIMZ was explored as a second‐stage polymerization at different concentrations and ratios of monomers in the presence of the previously prepared monodisperse poly(styrene‐co‐1‐vinyl imidazole) seed latex particles. The concentration of imidazole functional groups on the surface of the latex particles could also be varied through the rearrangement of hydrophilic imidazole groups by varying the second‐stage monomer addition process such as the utilization of monomer‐swollen seed particles or a shot addition of monomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 120:5753–5762, 2006     

Factors influencing magnetic polymer microspheres prepared by dispersion polymerization

Magnetic iron oxide (Fe₃O₄) was prepared by a coprecipitation method. Core–shell composite magnetic polymer microspheres with carboxyl groups were synthesized by the dispersion polymerization of styrene and acrylic acid in the presence of magnetic oxide, and dibenzoyl peroxide was used as an initiator. The synthesized magnetic polymer microspheres were characterized with X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and so forth. The results indicated that the product was single‐phase Fe₃O₄, and its average size was about 10 nm. The configuration of the microspheres, which contained carboxyl groups, was spherical, and the average size was about 2 μm. The results of vibrating sample magnetometry tests showed that the magnetic powders produced by different surfactants had different saturation magnetizations. When poly(ethylene glycol) with a weight‐average molecular weight of 4000 was used as a surfactant, the saturation magnetization of the samples reached 69.2 emu/g. The factors that affected the shape, magnetism, size, and distribution of the microspheres were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Syntheses of acrylate core/shell imbiber beads by seeded suspension copolymerization and one‐stage copolymerization for solvent absorption–desorption

Seeded suspension copolymerization or a one‐stage copolymerization was used to synthesize acrylate core/shell imbiber beads. A two‐stage polymerization technique was used for seeded suspension polymerization. The seed particles for poly(methyl acrylate) or poly(2‐ethylhexyl acrylate) were synthesized first in a mixed solvent of toluene/isooctane containing the ethylene glycol dimethacrylate (EGDMA) crosslinking agent. These beads were swollen in styrene‐EGDMA‐BPO (benzoyl peroxide) and then polymerized in the aqueous phase to produce the polystyrene (PS) shell. The one‐stage copolymerization was carried out in toluene/isooctane containing methyl methacrylate (MMA), styrene (St), EGDMA, and BPO at 75°C for 10 h to give a core/shell copolymer of St‐MMA morphology. The appearance of core/shell imbiber beads prepared from these two techniques varied from monomer to monomer. This article describes the preparation, characterization, and application of the core/shell beads for organic solvent absorption/desorption. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 670–682, 2002     

Preparation and characterization core‐shell particles and application for E‐Ink

the core‐shell particles were prepared by dispersion copolymerization. The core‐shell particles were characterized with Fourier‐transform infrared spectroscopy, Transmission electron microscope and scanning electron microscope. The dispersion stability and electrophoretic performance of core‐shell particles were studied in the mixed medium of tetrachloroethylene and cyclohexance. Microcapsules containing the core‐shell particles were prepared by coacervation. Results showed that the core‐shell particles had good dispersion stability and it had no electric response, which could be used as grounding particles for E‐Ink. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1195–1199, 2007     

Synthesis and characterization of air‐stable magnetic Fe composites microspheres of narrow size distribution

Air‐stable Fe magnetic nanoparticles entrapped within carbon and porous crosslinked polystyrene microspheres of narrow size distribution were prepared by the following sequential steps: (1) Polystyrene/poly(divinyl benzene) and polystyrene/poly(styrene‐divinyl benzene) uniform micrometer‐sized composite particles were prepared by a single‐step swelling of uniform polystyrene template microspheres dispersed in an aqueous continuous phase with emulsion droplets of dibutyl phthalate containing the monomers divinyl benzene and styrene and the initiator benzoyl peroxide. The monomers within the swollen polystyrene template microspheres were then polymerized by raising the temperature to 73°C; (2) Porous poly (divinyl benzene) and poly(styrene‐divinyl benzene) uniform crosslinked microspheres were prepared by dissolution of the polystyrene template part of the former composite particles; (3) Uniform magnetic poly(divinyl benzene)/Fe and poly(styrene‐divinyl benzene)/Fe composite microspheres were prepared by entrapping Fe(CO)₅ within the porous crosslinked microspheres, by suction of the Fe complex into the dried porous particles, followed by decomposition of the encapsulated Fe(CO)₅ at 200°C in Ar atmosphere; (4) Uniform magnetic air‐stable C/Fe composite microspheres were prepared similarly, apart from changing the decomposition temperature from 200 to 600°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

硅烷化胺基磁性微球的合成与表征

采用溶液聚合法制备具有良好悬浮性和磁响应性的硅烷化胺基磁珠,对胺基磁性微球的形貌、结构、悬浮稳定性和磁响应性进行表征.研究结果显示,硅烷化胺基磁性微球的平均粒径为15nm,粒径分布比较均匀,近似为球形的壳核结构,核为磁性基质,壳为3-胺基丙基三乙氧基硅烷;将硅烷化胺基磁珠用于悬浮稳定性研究表明,磁微球具有较好的悬浮稳定...     

双分散反相悬浮聚合制备吸水微球方法及装置

针对反相悬浮聚合存在热力学不稳定、分散剂难于清洗及难以实现工业化生产的缺点,基于落球法测黏度原理,建立了先后采用机械搅拌分散和自然沉降分散的反相悬浮聚合制备微球的方法,并设计了制备装置。该方法依靠搅拌速度及水相与油相体积比确定球径,然后在不采用分散剂的条件下,利用自然动力使微球边沉降边反应,有效避免微球粘连结块;制备装置结构简单,可实现连续生产,反应釜体高度需大于2 m以保证足够的反应时间,釜体材质为非极性材料以防止微球吸附釜壁。聚丙烯酰胺微球制备实验表明,制备工艺易于操作,微球不存在粘连,分散介质可重复使用,且无污染,便于工业化生产。     

Preparation of polyaniline coated polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) microparticles and the further fabrication of hollow polyaniline microspheres

In this article, the microparticles of polystyrene‐poly(styrene‐co‐sodium 4‐styrenesulfonate) (PS‐PSS) coated by polyaniline (PANI) were prepared and hollow PANI microspheres were further obtained by dissolving the core. First, surface‐sulfonated monodispersed PS was prepared by copolymerization of sodium 4‐styrenesulfonate (SSS) and styrene with dispersion polymerization method. Then aniline was polymerized on the surface of the surface‐sulfonated PS (PS‐PSS) by chemical oxidative polymerization. After purification, we prepared core‐shell (PS‐PSS)/PANI particles. Hollow PANI microspheres were prepared by dissolving the plastic PS core of the (PS‐PSS)/PANI particles in chloroform. The growth process of PANI on the surface of PS‐PSS particles was investigated and the hollow PANI microspheres were characterized. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

改性磁性壳聚糖微球的制备、表征及性能研究

以(NH4)2Fe(SO4)2.6H2O、NH4Fe(SO4)2.12H2O和壳聚糖为原料,经羟丙基化、胺基化,采用一步包埋法制备了一种新型的多胺基化磁性壳聚糖微球。通过正交实验法确定了磁性微球的最佳制备条件,即搅拌速度1200r/min,壳聚糖用量3.0g,环氧氯丙烷用量2.5mL,乙二胺用量2.5mL。并用IR、TG、XRD和SEM对其结构及形貌进行了表征。结果表明,Fe3O4磁性粒子已包埋了一层胺基化壳聚糖。磁性微球胺基含量为2.302mmol/g;呈较规则的球形,平均粒径为209nm,且具有顺磁性和良好的耐酸性。     

One‐step,one‐pot photoinitiation of free radical and free radical promoted cationic polymerizations

We describe here a novel approach to photoinitiate free radical and cationic polymerizations concurrently, involving the use of benzoin in conjunction with an onium salt such as diphenyl iodonium or N‐alkoxy pyridinium salt. On photolysis, benzoyl radicals formed from the decomposition of benzoin initiate free radical polymerization of methyl methacrylate. The hydroxy benzyl radicals formed concomitantly are readily oxidized to the corresponding cation by the onium salt to initiate cationic polymerization of cyclohexene oxide in the same system. Evidence for two independent polymerizations was obtained from studies involving gel permeation chromatography, extractions, and infrared and proton nuclear magnetic resonance analysis of the polymers. The effect of the type of the onium salt on each polymerization was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2389–2395, 2002     

新型磁性聚苯乙烯微球的制备及表征

为了制备一种以四氧化三铁磁性纳米粒子为壳、聚苯乙烯为核的新型高分子功能材料,并有望应用于磁稳定流化床反应器,采用悬浮聚合法制备了四氧化三铁纳米粒子包覆聚苯乙烯的磁性微球。运用扫描电镜（SEM）、红外光谱（FT-IR）、振动样品磁强计（VSM）、热失重（TGA）等测试手段,分析并表征了磁性聚苯乙烯微球的形貌特征、粒径、磁学性能及四氧化三铁包覆量。实验结果表明,所得磁性聚苯乙烯粒子为球状微球,粒径为150~200 μm且分布较窄;磁性聚苯乙烯微球的四氧化三铁包覆量达到7.81%（质量分数）,最高饱和磁化强度为3.97 A·m2/kg。     

Preparation and characteristics of Tryptophan‐imprinted Fe3O4/P(TRIM) composite microspheres with magnetic susceptibility by inverse emulsion–suspension polymerization

Tryptophan‐imprinted Fe₃O₄/P(TRIM) composite microspheres with magnetic susceptibility (MS‐SMIPs) were prepared by inverse emulsion–suspension polymerization, according to the principle of molecular imprinting technique, using magnetite Fe₃O₄ particles as magnetically susceptible component, methacrylic acid (MAA) and acrylamide (AM) as functional monomers, trimethylolpropane trimethacrylate (TRIM) as polymeric matrix components, and hydroxy ethyl cellulose (HEC) as dispersant. The external morphology and the inner structure of MS‐SMIPs were observed by SEM. SEM photographs showed that the resulting MS‐SMIPs were regularly spherical in external morphology and had a large quantity of spherical microvoids inside. The effects of the amount of Fe₃O₄ on particle size and morphology of MS‐SMIPs were investigated in detail. The results indicated that the amount of Fe₃O₄ affected particle size distribution and morphology of MS‐SMIPs obviously. The magnetic characteristics of MS‐SMIPs were measured by vibrating sample magnetometer, and the results showed that the resulting MS‐SMIPs had a certain magnetic response to external magnetic fields. Adsorption properties, molecular recognition selectivity, and regeneration recognition selectivity of MS‐SMIPs were investigated using tyrosine and phenylalanine as control molecules, and characterized by high performance liquid chromatography. It was shown that the resulting MS‐SMIPs exhibited a good recognition selectivity for tryptophan, and the relative separation factor (β) was 2.75, and MS‐SMIPs also exhibited higher regeneration recognition selectivity, and the separation factor was 1.83 and 1.80 in first regeneration and second regeneration, respectively. The effect of the amount of functional monomers on molecular recognition selectivity was investigated, and the mechanism of imprinting and recognition was analyzed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3241–3250, 2006     

Characterization of macroporous 1‐vinyl‐2‐pyrrolidone copolymers obtained by suspension polymerization

Radical suspension copolymerization of 1‐vinyl‐2‐pyrrolidone (VP) with three different cross‐linkers: divinylbenzene (DVB), trimethylolpropane trimethacrylate (TRIM), and di(methacryloxymethyl) naphthalene (DMN) was used to prepare macroporous microspheres. During the copolymerization, the mixture of toluene and n‐dodecane as a pore‐forming diluent was used. All samples were characterized in terms of particle size and distribution, nitrogen content, specific surface area total pore volume, and pore size distribution. It was found that specific surface area of the obtained beads is strongly dependent on the diluent system and the type of cross‐linker and achieves value from 27 to 845 m²/g. To determine the influence of chemical structure of cross‐linkers on the selectivity and polarity of the copolymers, inverse gas chromatography was applied. In addition, VP–DVB and VP–DMN copolymers were modified by sulfonation into cation‐exchangers with cation exchange capacity equal 1.98 and 2.31 mmol/g, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Compatible thermoplastic starch/polyethylene blends by one‐step reactive extrusion

In the presence of dicumyl peroxide (DCP), the thermal plasticization of starch and its compatibilizing modification with polyethylene was accomplished by one‐step reactive extrusion in a single‐screw extruder at the same time. Because of the formation of polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) during the extrusion, it was used as the compatibilizer between the thermoplastic starch and polyethylene. The blending samples were characterized by means of thermogravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic thermal mechanical analysis (DTMA) and Fourier‐transform infrared (FTIR) analysis. The experimental results showed that in the presence of DCP the addition of MAH improved the mutual dispersion of molecules in thermoplastic starch and polyethylene. From TGA, we concluded that the thermal stability of the blends with MAH was improved compared with the blends without MAH. The DTMA and FTIR results indicated that, with the addition of MAH, the compatibility of molecules between thermoplastic starch and polyethylene in the blends was improved. Copyright © 2004 Society of Chemical Industry     

Preparation of hydroxyapatite/Ca‐alginate composite microspheres via inverse suspension crosslinked method

Composite microspheres were prepared with hydroxyapatite (HA) and Na‐alginate (ALG) via inverse suspension crosslinked method (ISCM). Chloroform/hexane (1 : 2 (volume)) was used as continuous phase, ethyl cellulose (EC) as disperser, mixture of HA powder and ALG solution as dispersed phase, and calcium chloride as crosslinking agent. Morphology of the composite microspheres and HA distribution state were observed by optical microscope. According to the compositions studied, the sample with 0.2 g of EC gives the best continuous phase. The sample with 25 mL/min of adding speed and 120 r/min of stirring speed gives the best adding and stirring conditions. Two kind of the composite microspheres of 50/50 and 70/30 HA/ALG were prepared via ISCM. They are with specific gravity of 1.06 and 1.15, and water content of 88 and 81%, respectively. The size of the dried microspheres is mainly in the range of 125–425 μm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2034–2038, 2007     

Preparation of poly(vinyl acetate) microspheres with narrow particle size distributions by low temperature suspension polymerization of vinyl acetate

To estimate influences of suspension polymerization conditions including conversion, polymerization temperature, stirring rate, initiator concentration, monomer concentration, and suspending agent concentration on the volume average diameter (D_avg) and particle size distribution (PSD) of poly(vinyl acetate) (PVAc) microspheres, vinyl acetate (VAc) was suspension‐polymerized at low temperature using 2,2′‐azobis(2,4‐dimethylvaleronitrile) as an initiator. The effects of each condition, on D_avg of PVAc microspheres, were expressed as follows, D_avg = [conversion]^a[temperature]^b[rpm]^c[ADMVN]^d[VAc]^f [suspending agent]^g. Logarithms of D_avg were linearly proportional to those of polymerization conditions, and their exponents, a, b, c, d, f, and g were calculated as 0.27, ?13.7, ?1.37, ?0.21, 0.58, and 0.29, respectively. Variations of PSDs, according to polymerization conditions, were examined by considering polymerization rate, droplet or suspension viscosity, and droplet break‐up/coagulation equilibrium. From these results, PVAc microspheres with various sizes and narrow PSDs were obtained effectively under carefully controlled polymerization conditions, which can be used as promising precursors of novel PVA microspheres through heterogeneous surface saponification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4064–4070, 2006