单分散多孔聚合物微球的制备及其反相色谱应用

用分散聚合的方法制得单分散微米级聚苯乙烯微球(PS),以此聚苯乙烯微球作为种子,以邻苯二甲酸二丁酯为溶胀剂,苯乙烯为单体,二乙烯基苯为交联剂,甲苯为致孔剂,采用种子溶胀聚合的方法制得粒径分布较窄的多孔高交联的聚苯乙烯-二乙烯基苯微球(PS-DVB)。研究了交联剂与致孔剂的加入量对微球形貌、粒径及孔结构参数的影响。结果表明,所得多孔微球球形圆整,库尔特测得平均粒径为5.067~5.520μm,粒径分布窄,D90/D10为1.23~1.56,孔结构可控,并以此多孔微球作为反相色谱填料基质,理论塔板数每米可达6 000~15 000,可以用作高效液相色谱(HPLC)填料。     

Preparation of nano‐TiO2/polystyrene hybride microspheres and their antibacterial properties

This study provided a facile method to prepare nano‐TiO₂/polystyrene hybride microspheres in ethanol solution. The formation of titanium dioxide (TiO₂) nanoparticles and hybrid microspheres were verified by FTIR, SEM, transmission electron microscopy, thermogravimetric analysis, and X‐ray powder diffraction. Monodispersed colloid TiO₂ nanoparticles with small particle sizes were obtained, and the average particle size could be effectively controlled from about 10 nm. The antibacterial activity of the organic microspheres and hybride microspheres was also investigated against Escherichia coli. They were able to efficiently inhibit the growth and the multiplication of E. coli under the UV. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Different dispersion polymerization strategies influence the quality of fluorescent poly (St‐co‐GMA) microspheres

The polymerization strategy plays a vital role in the preparation of functional microspheres. In this work, fluorescent poly (styrene‐co‐glycidyl methacrylate) (PSt‐GMA) microspheres were synthesized via one‐stage and two‐stage dispersion polymerization with 4‐Bis(5‐phenyl‐1,3‐oxazol‐2‐yl)benzene (POPOP) as fluorescence agent. SEM and DLS were adopted to characterize the properties of prepared microspheres. The UV‐vis and fluorescence spectroscopy were used to analyze the mechanisms of two‐stage dispersion polymerization. The experimental results showed that the size distribution and fluorescence intensity of prepared microspheres could be improved by two‐stage dispersion polymerization compared to one‐stage dispersion polymerization. In addition, according to UV‐vis, the interactions between POPOP and Poly (N‐vinyl pyrrolidone) (PVP) as well as POPOP and Glycidyl methacrylate (GMA) could affect the particle size and its distribution. UV‐vis and fluorescence spectra implied that the POPOP existed outside of the particle's core via two‐stage strategy. The monomer conversion of styrene was similar at the beginning of reaction; however, the monomer conversion of styrene by two‐stage strategy was higher than that of by one‐stage strategy. In a word, two‐stage dispersion polymerization could prepare fluorescent microspheres with the monodispersion micrometer‐size and high quality. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41927.     

Preparation,structure, and properties of poly(vinyl acetate‐co‐methyl methacrylate) nanocomposite microspheres with exfoliated montmorillonite through using two‐stage in situ suspension polymerization

Effective encapsulation of montmorillonite intermediate particles (I‐MMT) within poly (vinyl acetate‐co‐methyl methacrylate) (PVAMMA) copolymer by in situ suspension polymerization was performed. The I‐MMT encapsulation, layer exfoliation behavior, chemical composition, particle size distribution and thermostability of PVAMMA/I‐MMT nanocomposite microspheres were characterized by electron microscopies, X‐ray diffraction (XRD), laser particle analyzer, and thermogravimetric analysis (TGA). Swelling behaviors of the nanocomposite microspheres in various cationic salt solutions (NaCl and CaCl₂) and anionic salt solution (NaCl and Na₂SO₄) were also investigated. Results showed that the properties of layer dispersion surface and expansion of these nanocomposite microspheres were well achieved. The synthetic yields of the nanocomposites decreased as the I‐MMT loading increased. These nanocomposite microspheres had an average size from 96.8 μm to 138.4 μm with narrow particle size distribution, loose, and porous surface morphology. XRD patterns clearly proved the exfoliation of MMT layers in the copolymer matrix, which was consistent with TEM analysis. These nanocomposite microspheres showed higher negative zeta potential and higher thermal stability than those of the copolymer microspheres, which was due to the layer exfoliations in encapsulated microspheres. These selected microspheres with 10 to 70 μm diameters provided effectively plugging in the micrometer‐sized core channels through deformation and migration process in plugging experiments, which made them be the candidate materials for modifying the porous reservoir to enhance oil recovery in petroleum engineering. POLYM. COMPOS., 35:1104–1116, 2014. © 2013 Society of Plastics Engineers     

Kinetics of polymerization and particle stabilization mechanism on dispersion copolymerization of styrene and divinylbenzene

Monodisperse highly crosslinked microspheres were prepared by dispersion copolymerization of styrene and divinylbenzene in an ethanol/water medium using poly(N‐vinylpyrrolidone) (PVP) as the stabilizer. The locus of polymerization and growth of particles were investigated. The polymerization kinetics, average particle diameter (D_n), polydispersity index (PDI), and numbers of particles (N_p) were presented. When the initial styrene concentration is below 20%, the results indicate that the polymerization occurs in the particles, and the particles grow to their final size by the diffusion of monomer and oligomer into the existing particles. The polymerization rate can be described by the equation R_p = k[l]^0.87 ([St]^1.91 + [DVB]^0.09) (1 + [PVP]^0.01) exp(? 45.35/RT). The data from infrared spectroscopy demonstrated that the graft stabilizer was present. The dissolution experiments show that the crosslinking reaction occurred irregularly in batch dispersion polymerization. Using the postaddition approach, up to 3% divenylbenzene (DVB) was successfully incorporated in the synthesis of coagulum‐free substance, and monodisperse crosslinked 5 μ m microspheres with a superior resistance to solvents have been prepared. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2230–2238, 2002     

Thermally expandable microspheres with excellent expansion characteristics at high temperature

Thermally expandable core/shell particles with a poly(acrylonitrile‐co‐methacrylonitrile) shell and a hydrocarbon core (blowing agent) have been prepared by suspension polymerization. The objective of this study was to gain a deeper understanding of the parameters determining the expansion properties of these microspheres. It was found that the amount, the boiling point, and the structure of the blowing agent are important parameters for the expansion properties. For example, a higher maximum expansion was reached when using bulkier blowing agents and thus a lower diffusion rate through the polymer shell. Further, the amount and structure of the crosslinker were also found to be essential for the expansion properties. For this particular system, it was found that a dimethacrylate‐functional crosslinker gave significantly better expansion when compared with diacrylate‐ or divinylether‐based crosslinkers. Beside these parameters, it was also observed that the particle‐size distribution influence the expansion properties of the microspheres. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Factorial design optimization of polystyrene microspheres obtained by aqueous dispersion polymerization in the presence of poly(2‐ethyl‐2‐oxazoline) reactive stabilizer

The present study highlights the use of statistical design to establish an effective model for the synthesis of polystyrene microspheres by aqueous dispersion polymerization using poly(2‐ethyl‐2‐oxazoline) reactive stabilizer. The significant parameters (e.g. solvent polarity, stabilizer and initiator concentration) influencing the characteristic responses of the process such as yield, particle size and size distribution, as well as the interactions between the variables, were identified. The macromonomer concentration and solvent polarity influence both particle size and size distribution, whereas initiator concentration influences the yield. Analysis of the variance of process variables indicates that the models can be successfully used to describe the dispersion polymerization process. Moreover, the factorial design allows the development of microspheres with optimal properties with respect to size and size distribution. The experimental data regarding yield, particle size and size distribution of the optimized dispersion polymerization shows less than 7% difference compared with the predicted responses. In view of these results, the implementation of statistical design models represents an efficient solution for optimizing microparticle synthesis while aiming for industrial applications. © 2020 Society of Chemical Industry     

Synthesis and characterization of thermosensitive composite microsphere latex

Monodisperse aqueous latex dispersions, prepared from mixtures of styrene, N‐isopropylacrylamide, and N,N′‐methylenebisacrylamide, were characterized. Thermosensitive composite microspheres with diameters greater than 1.0 μm, consisting of a polystyrene core and a poly(N‐isopropylacrylamide) shell, were prepared. The morphology of the composite microspheres was observed with transmission electron microscopy, and the particle size of the composite microspheres was estimated with dynamic light scattering. The thermosensitive properties of the composite microspheres were evaluated via the hydrodynamic size of the composite microspheres. The particle size of the composite microspheres decreased with increasing temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 824–828, 2005     

The synthesis and characterization of lanthanide-encoded poly(styrene-co-methacrylic acid) microspheres

Lanthanide-encoded polystyrene microspheres with methacrylic acid (MAA) as a co-monomer and with diameters on the order of 2 μm and a very narrow size distribution were synthesized by two-stage dispersion polymerization (2-DisP). These microspheres were designed as a platform for mass cytometry-based bioassays. Different lanthanides (Ln) were loaded into these microspheres during the synthesis, through the addition of LnCl₃ salts and excess MAA to the reaction after about 10% conversion of styrene, i.e., well after the microsphere nucleation stage was complete. Different levels of MAA were employed to investigate the relationship between the number of carboxyl group on the particle surface and the amount of MAA used. The reaction remained well controlled with both 2 and 4 wt % MAA. As monitored by inductively coupled plasma (ICP) mass spectrometry, we found high incorporation efficiency (>95%) of Ln ions into the particles when the total amount of LnCl₃ salts in the reaction mixture was sufficiently small. The Ln incorporation efficiency decreased with the increasing amount of LnCl₃ salts. Mass cytometry analysis shows that individual microspheres contain ca. 10⁵-10⁸ chelated lanthanide ions, either a single element or a mixture of elements. This method of incorporating lanthanide into P(S-MAA) particles through the second stage of two-stage dispersion polymerization yields microspheres suitable for the highly multiplexed detection of biomolecules.     

Preparation of micron‐size monodispersed PS/P(St/MAA) microspheres by seeded dispersion polymerization

Uniform polystyrene (PSt) particles with the size of 1.9 μm were first prepared via dispersion polymerization, and then used as the seeds in a second‐stage dispersion copolymerization of styrene (St) and methacrylic acid (MAA) to produce carboxyl‐carrying microspheres. The PSt seed particles were swollen by monomer mixture of St and MAA, including an oil‐soluble initiator 2,2′‐azobisiso‐butyronitrile (AIBN), before polymerization. Finally, uniform PS/P(St/MAA) (polydispersity index, PDI = 1.02) microspheres with the size of 2.2 μm were obtained. The average particle size and size distribution of the final microspheres were investigated. MAA contents between 54 and 97 mg/g were detected from the PS/P(St/MAA) particles produced under different conditions. Dispersion medium has great influence on the kinetics of polymerization, due to its effect on the partitioning of monomers, solvents, and initiator in the particle phase, probably as well as on the conformation of the dispersion agent on the surface of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3586–3591, 2006     

Dispersion polymerization of uniform cross‐linked polystyrene microspheres in butan‐1‐ol

Butan‐1‐ol can be used as the solvent in the synthesis of poly(styrene‐co‐divinylbenzene‐co‐acrylic acid) microspheres by dispersion polymerization of a mixture of styrene, divinylbenzene (DVB), and acrylic acid (AA). Varying the proportion of the crosslinker DVB affects the size distribution and particle morphology profoundly, with 0.5–1.0% w/w producing spherical particles, whereas 2.0% w/w DVB produces irregular, concave morphologies. Varying the amount of AA from 5–7% w/w increases the average diameter of the spherical particles, whereas 9% w/w AA results in ovoid particles with dimpled surface morphology. In an optimized synthesis using 1.0% w/w DVB and 5% AA, uniform polymer microspheres with an average diameter of 0.8 µm and a coefficient of variation (CV) of diameter of 8.2% are produced. The use of a medium‐polarity solvent, such as butan‐1‐ol, as the solvent for dispersion polymerization will facilitate the incorporation of non‐polar moieties, such as organically‐passivated quantum dots, into the polymer during synthesis. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43103.     

Preparation and characterization of poly‐DL‐lactide–poly(ethylene glycol) microspheres containing λDNA

Polylactide (PLA) and a block copolymer, poly‐DL ‐lactide–poly(ethylene glycol) (PELA) were synthesized by bulk ring‐opening polymerization initiated by stannous chloride. A linear DNA molecule, λDNA, was used as the model DNA. PLA, PELA, λDNA‐loaded PLA and PELA microspheres were prepared by the solvent‐extraction method based on the formation of multiple w₁/o/w₂ emulsion. The particle‐size distribution, surface morphology, and DNA loading characterized the microspheres. The mean diameter of λDNA‐loaded PELA microspheres was proved to be 3.5 μm. The integrity of the λDNA molecules, after preparing the microspheres, was determined by agarose gel electrophoresis. The result suggested that most of the λDNA molecules could retain their integrity after being encapsulated by PELA. The PELA microspheres could also prevent λDNA from being degraded by DNase. The in vitro degradation and release of PLA, PELA, and λDNA‐loaded PELA microspheres were carried out in a pH 7.4 buffer solution at 37°C. Quantitatively, evaluating the molecular weight reduction, the mass loss, the particle‐size changes, and the particle‐size distribution changes also monitored the degree of degradation. The release profile was assessed by measurement of the amount of λDNA present in the release medium at determined intervals. The degradation profiles of the PELA microspheres were quite different from those of the PLA microspheres. The introduction of the hydrophilic poly(ethylene glycol) domain in PLA and the presence of λDNA within the microspheres exhibit the apparent influence on the degradation and release profiles. A biphasic release profile was proved, that is, an initial burst release during the first days, then a gradual release. It was demonstrated that the PELA microspheres could be used potentially as a controlled release‐delivery system for λDNA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2557–2566, 2002     

Effect of GMA on monodisperse epoxy‐functionalized polymer microsphere particles by dispersion copolymerization of styrene with glycidyl methacrylate

Monodisperse poly[styrene‐co‐glycidyl methacrylate (GMA)] microparticles were synthesized by dispersion copolymerization in a water–ethanol medium. The effects of various polymerization parameters on the particle size and size distribution of the dispersion copolymerization were investigated. The dispersion of polymer particles decreased when the GMA was added if the polystyrene homopolymer particles were polydispersed. The GMA acted as a comonomer as well as a costabilizer in the dispersion copolymerization of styrene with GMA. The solvency of the monomer increased with the concentration of GMA in the polymerization medium because GMA has a greater hydrophilicity than styrene, resulting in a large particle size and a slow polymerization rate. From an HCl–dioxane analysis of the poly(styrene‐co‐GMA) microparticles, great amounts of epoxy groups were detected after the completion of dispersion copolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1206–1212, 2001     

Synthesis of monodisperse crosslinked poly(styrene‐co‐divinylbenzene) microspheres by precipitation polymerization in acetic acid

Poly(styrene‐co‐divinylbenzene) microspheres with size ranging from 1.6 to 1.8 μm were prepared in acetic acid by precipitation polymerization. The particle size and particle size distribution were determined by laser diffraction particle size analyzer, and the morphology of the particles was observed with scanning electron microscope. Besides, effects of various polymerization parameters such as initiator and total monomer concentration, divinylbenzene (DVB) content, polymerization time and polymerization temperature on the morphology and particle size were investigated in this article. In addition, the yield of microspheres increased with the increasing total monomer concentration, initiator loading, DVB concentration and polymerization time. In addition, the optimum polymerization conditions for synthesis of monodisperse crosslinked poly(styrene‐co‐divinylbenzene) microspheres by precipitation polymerization in acetic acid were obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

微米级单分散聚苯乙烯微球的制备

以苯乙烯(St)为单体、偶氮二异丁腈(AIBN)为引发剂、聚乙烯吡咯烷酮(PVP)为分散稳定剂,在乙醇-水反应介质中,采用分散聚合法制备了微米级单分散聚苯乙烯(PS)微球。分别用电镜扫描和激光粒度仪表征了PS微球表面形貌、粒径及粒度分布,探讨了影响PS微球粒径及粒度分布的诸多因素。结果表明,AIBN用量(以单体质量计,下同)大于5.0%或PVP用量(以单体质量计,下同)小于2%时,PS粒子间有聚并现象;当St浓度为10%、AIBN用量为2.5%、PVP用量为5.5%、醇水质量比为90∶10、聚合温度为70℃时,制备的PS微球粒径为1.612μm、粒度分散系数为0.357,微球单分散性及球形度最佳。     

细乳液聚合制备二氧化钛/聚苯乙烯复合微球及其形貌分析

采用细乳液聚合法,以γ-甲基丙烯酰氧基丙基三甲基硅烷改性的TiO2粒子为核,制备了核壳结构的TiO2/聚苯乙烯(PS)复合微球。研究了超声细乳化时间、乳化剂十二烷基硫酸钠(SDS)的浓度、TiO2用量对细乳液粒径及其分布的影响。通过纳米粒度与Zeta电位分析仪、红外光谱、透射电镜等分析手段对产物进行了表征。结果表明,随着超声细乳化时间的增加,初始液滴的粒径变小。聚合后的乳胶粒粒径随着SDS浓度的增大而减小;TiO2用量不足导致乳胶粒粒径分布变宽,且出现双峰;制备所得的TiO2/PS复合微球粒度分布较为均匀,平均直径为176.5 nm,球形规整度较好。     

Preparation of microspheres with silicone oil cores and poly(N‐isopropylacrylamide) shells by physical coating

Surfactant‐free thermoresponsive microspheres with a silicone oil cores surrounded by poly(N‐isopropylacrylamide) shells have been successfully prepared by physical coating method for the first time. The influences of reaction temperature, N‐isopropylacrylamide (NIPAM) dosage, and stirring rate on the formation, morphology, particle size, and monodispersity of microspheres were experimentally studied. In the preparation of microspheres, when reaction temperature was above the lower critical solution temperature of poly(N‐isopropylacrylamide), products had higher yield of particles and narrower size distribution. With increasing NIPAM dosage, the particle diameter became larger and the shell layer thickened and the monodispersity became better. With increasing stirring rate, the particle diameter and the monodispersity decreased obviously. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5571–5576, 2006     

种子溶胀法制备单分散多孔聚合物微球的溶胀动力学研究

以微米级聚苯乙烯为种球,进行了两步种子溶胀法制备多孔聚合物微球的溶胀动力学研究,用光学显微镜、马尔文粒度分析仪、扫描电镜(SEM)和比表面积孔径分布测定仪(BET)等手段,对微球的溶胀形貌和孔结构进行了表征,优选出较好的溶胀条件是:以邻苯二甲酸二丁酯为溶胀剂,用超声乳化方式制备乳液,单位质量种球所用溶胀剂量为1.5mL,在35℃下10h即可完成溶胀,得到粒径分布良好的活化微球。研究发现,超声乳化分散方式的引入,可将溶胀时间由传统的24h缩短至10h,这可能是由于超声波的空穴效应所产生的巨大磁场加速了溶胀平衡状态建立的缘故。     

Vermiculite/polyacrylamide copolymers microspheres for profile control in oilfields

Polyacrylamide copolymers (PAMVT) microspheres were prepared through inverse emulsion polymerization by using acrylic acid (AA), 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as functional monomers, N,N′‐methylene bis‐acrylamide (MBA) as crosslinker and modified vermiculite (MVMT) with the single‐factor experiments. The initial and swelled particle sizes were tested through the dynamic light scattering (DLS). The swelled particle size under the optimum conditions could be 1.98 μm. The structure was characterized through Fourier transform infrared (FTIR), which indicated that vermiculite has successfully modified and the polymerization reaction was completed. The scanning electron microscopy (SEM) shows that MVMT was evenly filled with PAM copolymers. The water absorption capacity can be up to 80.2%. The recovery efficiency of the water flooding was increased from 69.33% to 77.56%. All these results indicated that the microspheres emulsions could be used as profile control agent to enhance the recovery efficiency. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44918.     

Novel methyl cellulose‐grafted‐acrylamide/gelatin microspheres for controlled release of nifedipine

Naturally available carbohydrate polymers such as methylcellulose (MC) and gelatin (Ge) have been widely studied in the previous literature for controlled release (CR) applications. In this study, methyl cellulose‐g‐acrylamide/gelatin (MC‐g‐AAm/Ge) microspheres were prepared by water‐in‐oil (W/O) emulsion method and crosslinked with glutaraldehyde to encapsulate with nifedipine (NFD), an antihypertensive drug. The microspheres prepared were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and laser particle size analyzer. DSC thermograms of NFD‐loaded AAm‐MC/Gel microspheres confirmed the molecular level distribution of NFD in the matrix. SEM indicated the formation of spherical particles. Swelling experiments supported the drug diffusion characteristics and release data of the matrices. Cumulative release data were analyzed using an empirical equation to understand the nature of transport of drug through the matrices. Controlled release characteristics of the matrices for NFD were investigated in pH 7.4 media. Drug was released in a controlled manner up to 12 h. Particle size and size distribution of the microspheres as studied by laser light diffraction particle size analyzer indicated their sizes to be around 120 μm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010