Preparation of polystyrene particles with different morphologies
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Abstract Micron‐sized, cross‐linked polystyrene (PS) particles with different morphologies were prepared by the developed dispersion polymerization. By scanning electron microscope (SEM) observation, it was found that these PS particles had interesting shapes such as deformed sphere, hollow hemisphere and spheroid‐like shape when initial monomer concentration, reaction time, and temperature and addition way of the reagent added in the third stage were different. The shape of the PS particles was changed from hollow hemisphere to spheroid‐like shape with prolongation of the reaction time. It was remarkable that the rough surface of hollow‐hemisphere‐like PS particles became smooth and the hollow structure of smooth‐hollow‐hemisphere‐like PS particles grew into solid structure at the same time. The formation mechanism behind these phenomena was discussed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics EngineersKeywords:
Polystyrene
Spheroid
Dispersion polymerization
Abstract Cultured hepatocytes have been explored for use in a bioartificial liver. Spheroids formed by cultured hepatocytes exhibit enhanced liver‐specific functions. The kinetics of spheroid formation, using rat hepatocytes, was studied on positively charged surfaces that were either uncoated or coated with collagen or (hydroxyethyl)methacrylate (HEMA). Optimal spheroid formation was obtained on positively charged (Primaria) surfaces at inoculum densities in the range of (3–9) × 10 4 cells/cm 2 . Cells initially attached and spread out on the surface. Subsequent retraction led to the emergence of small clumps of cells attached to the surface, from which spheroids formed and shed off into suspension. The process of spheroid formation took more than 72 h and was accompanied by a decrease in the surface area occupied by attached cells. Optical sectioning of fluorescently stained spheroids using confocal microscopy indicated that most of the cells in the spheroid were viable. Spheroids also maintained a constant albumin synthesis rate for over 7 days in culture. Spheroid formation was evaluated in terms of the changes in spheroid diameter, the surface area covered by attached cells, and the total protein content of the fraction of cells that formed spheroids. The quantitative methodologies developed were used to assess the effect of inoculum cell concentration on spheroid formation and to evaluate the kinetics of spheroid formation on different surfaces both favorable and nonfavorable to spheroid formation.
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Well dispersed single polystyrene(PS) particles at 80～100nm were prepared by emulsion polymerization.Using polystyrene and paraffin wax,paraffin—polystyrene spherical particles were synthesized through the dispersion polymerization process.The factors of influencing the synthesis process and size distributions were analyzed and the experimental results showed that the PS particles were well dispersed and their diameters were small.Furthermore,employing a proper synthesis method,the paraffin—polystyrene spherical particles were prepared with high yield rate,small size and uniform distribution.
Polystyrene
Paraffin wax
Dispersion polymerization
Emulsion polymerization
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The homogenous polystyrene micro-sphere particles were prepared by dispersion polymerization.The effects of monomer,stabilizer,initiator and ratio of solvent reaction media on the size and size distribution of the polystyrene micro-spheres were investigated.Polystyrene micro-spheres were characterized by fourier transform infrared spectrometer(IR) and scanning electron microscope(SEM).Mono-disperse polystyrene micro-spheres in the size range of 10.06 μm were prepared when the quality percent of monomer is 29.52%,stabilizer PVP is 3.94%,initiator AIBN is 2.36% and solvent is alcohol.
Polystyrene
Dispersion polymerization
Suspension polymerization
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Monodisperse polystyrene microspheres with micron size were prepared by dispersion polymerization. The factors influencing the size of polystyrene microspheres were investigated. The experimental results showed that the size of polystyrene microspheres decreased with increasing amount of stabilizer, increased with increasing amount of monomer and initiator. The amount of stabilizer and monomer were major factors influencing the size distribution of polystyrene microspheres. The size of polystyrene microspheres decreased with increase of the solvency of reaction media and the size distribution hardly changed. The size of polystyrene microspheres increased with increase of the reaction temperature and the size distribution hardly changed.
Polystyrene
Dispersity
Dispersion polymerization
Suspension polymerization
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The dispersion polymerization of styrene was successfully carried out under microwave irradiation in the EtOH/H_2O medium, which PVP and AIBN were used as stabilizers and initiators respectively. The monodisperse polystyrene microspheres could be prepared in the range from 200 nm to 500 nm, and the morphology, size and size distribution of the polystyrene microspheres were characterized by TEM, AFM and PCS. The results indicate that polystyrene microspheres prepared by microwave irradiation are much smaller and more uniformed than those obtained by conventional heating.
Polystyrene
Dispersity
Dispersion polymerization
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The radiation induced crosslinking of polystyrene is difficult because of its aromatic units, and the polymer degrades when irradiated in air. Therefore, the effects of gamma-ray irradiation on polystyrene in the presence of polyfunctional monomers such as trimethyl propanetrimethacrylate (TMPTM), dimethyleneglycol bis-allylcarbonate (DEGBAC) and propyleneglycol bis-allylcarbonate(PGBAC). These monomers readily polymerize by the ra diation with small dose. In the case of DGBAC and DPGBAC (allyl monomers) the dose required for crosslinking of polystyrene was higher than that with TMPTM (vinyl monomer). The relationship between doses and % of gel formed as well as radiochemical yields for gelation and degradation for those poly functional monomers will be presented.
Polystyrene
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Polystyrene
Dispersion polymerization
Photoconductivity
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A kind of monodispersed crosslinked polystyrene microsphere were prepared by dispersion polymerization using polystyrene as monomer, N,N′-4,4′-diphenylmethanebismaleimide(BDM) as crosslinker.The effect of the concentrations of monomer, initiator, stabilizer and crosslinker on the particle size and size distribution of polystyrene microspheres were investigated. Monodispersed crosslinked polystyrene microspheres in an average diameter of 3.03 μm and a dispersion parameter of 0.05 were prepared on the optimum conditions. Thermal analysis and solvent-resistant experiment show crosslinked polystyrene microspheres have better heat-resistant and solvent-resistant properties than linear polystyrene microspheres. When the weight loss of 5%, Thermal decomposition temperature of crosslinked polystyrene microspheres was increased than linear polystyrene microspheres from 306 ℃ to 328 ℃.
Polystyrene
Dispersion polymerization
Dispersity
Suspension polymerization
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Microsphere-based assay is a powerful platform to carry out biological detection.The carboxyl functionalized,micro-sized polystyrene microsphere is important carrier in the microsphere-based assay.Mono-dispersed polystyrene particles with the size range of 2.0 μm to 7.0 μm were synthesized by dispersion polymerization.The surface of microspheres was carboxyl functionalized by post-modification.It is demonstrated that the functionalized polystyrene microsphere can be well-coupled with monoclonal antibodies with comparable performance achieved as that of commercial carboxyl polystyrene microspheres(Spherotech Inc.).
Polystyrene
Dispersion polymerization
Suspension polymerization
Surface Modification
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In this paper, without any additional temperature, pressure and other physical energies, the dispersion polymerization of styrene was directly initiated by magnetic field effect at room temperature. The results showed that the polystyrene microspheres (Mw=96856, Mn=13162) prepared through dispersion polymerization of styrene initiated by alternative magnetic field effect had diameters between 1 and 2μm. The polystyrene microspheres prepared in constant magnetic field had some deformed impurities; the polystyrene microspheres prepared in alternative magnetic field had good sphericity and smooth surface, and had no defects and impurities.
Polystyrene
Dispersion polymerization
Sphericity
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