Dispersion Polymerization Method Research Articles

Facile Preparation of Litchi-Like Polystyrene-Silica Hybrid Particles via Dispersion Polymerization

The composite particles with litchi-like morphologies attributing to the combination of inorganic silica seed and polymer nodules were synthesized successfully using a modified dispersion polymerization method. Dispersion polymerization of styrene was achieved in the presence of silica particles and the formed polystyrene nanoparticles were absorbed onto the surface of silica particles. The effects of the adding amount of St monomer on the particle morphologies was investigated.

Conducting poly(N-methylaniline)-coated cross-linked poly(methyl methacrylate) nanoparticle suspension and its steady shear response under electric fields

Abstract Core–shell-structured poly(methyl methacrylate) (PMMA)/poly(N-methylaniline) (PNMA) composite particles were fabricated using a facile method and their electrorheological (ER) characteristics under applied electric fields were examined. Initially, monodisperse PMMA nanoparticles were obtained using a dispersion polymerization method. Subsequently, the PNMA shell was coated by chemically oxidative polymerization. For this purpose, the surface of PMMA was modified by glycidyl methacrylate, ethylene glycol dimethacrylate, and oxydianiline as swelling, cross-linking, and grafting agents, respectively. The ER performance of the chain-like structures of PMMA/PNMA microparticles, when dispersed in silicone oil, was observed by optical microscopy. The ER properties were investigated using a rotational rheometer to examine the effects of applied electric fields, focusing on the steady-shear response, and specifically the Cho–Choi–Jhon model was used to describe the flow curves of the particles over the entire shear-rate region.

Thermally stable polyimide nanocomposite films from electrospun BaTiO3 fibers for high-density energy storage capacitors

PI composite films with electrospun BT fibers were fabricated using the in situ dispersion polymerization method. The microstructures, thermal and dielectric properties of the BT fibers and composite films were investigated.

Synthesis of Fe3O4-NPs/SiO2 core-shell hollow microspheres and application in water treatment

Fe3O4-nanoparticles/polystyrene (Fe3O4-NPs/PS) composite microspheres were synthesized using a modified dispersion polymerization method. The distribution and content of Fe3O4-NPs in the microspheres were studied. Using the Fe3O4-NPs/PS microspheres as templates, Fe3O4-NPs/SiO2 core-shell hollow microspheres with excellent magnetic property and large cubage were synthesized facilely. The obtained Fe3O4-NPs/SiO2 core-shell hollow microspheres had a potential application in detoxification extraction and rapid waste removal with a very simple procedure.

Synthesis of poly(aniline-co-o-toluidine) nanocolloidal particles in aqueous poly(styrene sulfonic acid) by dispersion polymerization method

Nanocolloidal poly(aniline-co-o-toluidine) particles were synthesized by dispersion polymerization using different weight ratios of steric stabilizer poly(styrene sulfonic acid). The dispersed nanocolloidal particles ranging from 10 to 100 nm were inspected by transmission electron microscopy and particle size analyzer. The strong doping level of particles at higher weight ratios of stabilizer was analyzed by elemental analysis. The functional groups of particles were identified by Fourier transform-infrared spectra. A reduction of the conjugation length in the particles leads to the homogeneous mixture of phases which was confirmed by scanning electron microscopy and UV–visible spectra. The blue shift polaron band has confirmed the change in conjugation length of the particle. High thermal stability of particles was examined by thermogravimetry analysis.

Monodisperse poly(2-methylaniline) coated polystyrene core–shell microspheres fabricated by controlled releasing process and their electrorheological stimuli-response under electric fields

A core–shell structured electro-responsive electrorheological (ER) particle system comprised of monodisperse poly(2-methylaniline)-coated polystyrene (PS/PMAN) microspheres was fabricated by applying a controlled swelling-releasing technique to pre-fabricated micron-sized PS seeds using a dispersion polymerization method. Compact wrapping of the PS microparticles with semiconducting PMAN without a de-doping process was examined by scanning electron microscopy and transmission electron microscopy. Fourier-transform infrared spectroscopy and thermogravimetric analysis also confirmed the chemical composition and thermal stability of the particles, respectively. Rheological characteristics of the PS/PMAN microsphere based ER fluid dispersed in silicone oil at various electric field strengths revealed a typical ER response under both steady shear flow and dynamic oscillation, demonstrating its mechanism of a conductivity model with a slope of 1.5.

Photo-bleaching characteristics of oxygen-sensitive particles

This study examined the photo-bleaching characteristics of oxygen-sensitive particles (OSPs) using a high-speed imaging technique. The OSPs were fabricated by a dispersion polymerization method and dipping method using porous micro spheres. Two representative oxygen indicator molecules, platinum octaethyl porphyrin (PtOEP) and platinum (II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP), were used to make four kinds of OSPs. A ultraviolet light emitting diode (UV-LED, M385L2, THORLABs) with a wavelength of 383 nm, a microscope with a 20X objective lens and a high-speed camera were adopted for the high-speed imaging of OSPs. The photo-bleaching characteristics of the OSPs were compared according to the time and power of UV-LED. The dispersion-polymerized OSPs had higher photostability than the porous OSPs, and the PtTFPP-embedded porous OSPs were more stable than the PtOEP-embedded porous OSPs due to the molecular structural characteristics. The dispersion-polymerized OSPs incorporated with PtOEP were more stable than the dispersion-polymerized OSPs incorporated with PtTFPP.

Preparation of Porous Hydroxylapatite Using Polystyrene Microspheres as Pore Former

Polystyrene (PS) microspheres were prepared by dispersion polymerization method and using PS microspheres as pore former porous hydroxylapatite (HA) was prepared by Liquid phase precipitation method. The phase constituent was analyzed by X-ray diffraction(XRD) and by Fourier transform infrared(FTIR) and the microstructure was observed under scanning electron microscopy (SEM), field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The results showed that the prepared porous HA was of high purity and their pores were evenly distributed, with pore about 200nm in diameter. PS microspheres were probably the most economic and environmental pore-forming materials.

Preparation and encapsulation of white/yellow dual colored suspensions for electrophoretic displays

C.I. Pigment Yellow 181 (PY181) composite particles encapsulated by polyethylene (PE) were prepared by dispersion polymerization method, and C.I. Pigment Yellow 110 (PY110) composite particles encapsulated by polystyrene (PS) with mini-emulsion polymerization method were achieved, respectively. The modified pigments were characterized by fourier transform infrared spectroscopy, scanning electron microscope and transmission electron microscope. Compared with the PE-coated PY 181 pigments, the PS-coated PY-110 particles had a narrow particle size distribution, regular spherical and average particle size of 450nm. Suspension 1 and suspension 3 were prepared by the two composite particles dispersed in isopar M. A chromatic electrophoretic display cell consisting of yellow particles was successfully fabricated using dispersions of yellow ink particles in a mixed dielectric solvent with white particles as contrast. The response behavior and the contrast ratio to the electric voltage were also examined. The contrast ratio of pigments modified by polystyrene was 1.48, as well as the response time was 2s, which were better than those of pigments modified by polyethylene.

Preparation and Characterization of Micron-Sized PMMA/SiO2 Composite Microspheres

Micron PMMA microspheres which had PVP-g-PMMA graft polymers on the surface were prepared via a dispersion polymerization method by using the PVP K-30 as the dispersant. Because of the PVP-g-PMMA graft polymers, SiO2 nanoparticles were successfully introduced to the PMMA microsphere’s surface through the TEOS hydrolysis method. SEM and other tests suggested micron-sized PMMA/SiO2 composite microspheres were successfully synthesized. SiO2 nanoparticles could grow on the PMMA microspheres, probably because SiO2 was attracted chemically to the carbonyl bonds on the PVP molecules.

High capacity adsorption of Cr(VI) from aqueous solution using polyethylenimine-functionalized poly(glycidyl methacrylate) microspheres

Polyethylenimine-grafted poly(glycidyl methacrylate) (PGMA–PEI) microspheres were prepared using the dispersion polymerization method and a two-step reaction with ethylenediamine (EDA) and polyethylenimine (PEI). The PGMA–PEI microspheres were then characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) and tested for their ability to remove hexavalent chromium (Cr(VI)) from an aqueous solution in batch tests. The results demonstrated that Cr(VI) adsorption depended significantly on pH. The optimized pH value for the Cr(VI) adsorption was 2.0. The adsorption isotherms of PGMA–PEI microspheres with Cr(VI) fit the Langmuir model. The maximum adsorption capacities were 460.83, 485.44 and 505.05mgg−1 for PGMA–PEI600, PGMA–PEI1800 and PGMA–PEI10,172 microspheres, respectively. The adsorption reached equilibrium within 10min and the experimental data fit the pseudo-second-order model. The obtained thermodynamic parameters (ΔG0, ΔH0 and ΔS0) showed that the adsorption of Cr(VI) was an endothermic and spontaneous process. Competition from coexisting ions of K+, Na+, Ca2+, Cu2+, Cl−, NO3−, H2PO4−, and HPO42− was insignificant except SO42−. The regeneration study revealed that PGMA–PEI microspheres could be repeatedly used with no significant loss of adsorption efficiency.

Reversible immobilization of glucoamylase onto magnetic polystyrene beads with multifunctional groups

A novel and simple process for the surface functionalization of micron-sized monodisperse magnetic polystyrene (PS) microbeads was reported. The polystyrene seed particles were prepared prior to the dispersion polymerization method. Afterwards, series of surface chemical modifications on polystyrene microspheres were conducted, and three end-functional microspheres with carboxyl, imidazolyl and sulphydryl groups were obtained. The functional magnetic polystyrene microspheres were prepared by impregnation and subsequent precipitation of ferric and ferrous ions into the polystyrene particles. Finally, the functional magnetic polystyrene was used for the reversible immobilization of glucoamylase via metal-affinity adsorption. The results indicated that the obtained immobilized glucoamylase presented excellent reusability, applicability, magnetic response and regeneration of supports. The magnetic PS microspheres retained >65% of its initial activity at 65°C over 6h; and the lowest residual activity of immobilized glucoamylase prepared by regenerated supports still remained about 50% of the initial activity after the 10th cycles.

Poly(dimethylsiloxane)-Stabilized Polymer Particles from Radical Dispersion Polymerization in Nonpolar Solvent: Influence of Stabilizer Properties and Monomer Type

Particles used in electrophoretic display applications (EPD) must possess a number of specific properties ranging from stability in a nonaqueous solvent, high reflectivity, low polydispersity, and high charge density to name but a few. The manufacture of such particles is best carried out in the solvent of choice for the EPD. This opens up new interests in the study of nonaqueous dispersion polymerization methods, which deliver polymer particles suspended in low dielectric constant solvents. We explore in this article the use of a poly(dimethylsiloxane) macromonomer for the stabilization of poly(methyl methacrylate) polymer particles in dodecane, a typical solvent of choice for EPDs. The use of this stabilizer is significant for this method as it is directly soluble in the reaction medium as opposed to traditionally used poly(12-hydroxystearic acid)-based stabilizers. Additionally, the present study serves as a baseline for subsequent work, where nonaqueous dispersion polymerization will be used to create polymer particles encapsulating liquid droplets and solid pigment particles. In this article, the influence of the macromonomer molecular weight and concentration on the properties of the synthesized particles is studied. In addition, we investigate the possibility of synthesizing polymer particles from other monomers both as a comonomer for methyl methacrylate and as the only monomer in the process. The influence of macromonomer concentration is also studied throughout all experiments.

Synthesis of anisotropic TiO2 hollow microspheres using cave particles as templates and application in water treatment

Anisotropic polystyrene (PS) particles with single cavity structures were synthesized using a modified dispersion polymerization method with divinylbenzene (DVB) as a crosslinker. Using the PS cave particles as templates, anisotropic titanium dioxide (TiO2) hollow microspheres were fabricated facilely. Due to possessing excellent photocatalytic activities, the obtained anisotropic TiO2 hollow spheres have potential applications in detoxification extraction and waste removal with very simple and efficient procedures.

Conjugated polymer shells on colloidal templates by seeded Suzuki–Miyaura dispersion polymerization.

The self-assembly of colloidal conjugated polymers presents a versatile and powerful oute towards new functional optoelectronic materials and devices. However, this strategy relies on the existence of chemical protocols to prepare highly monodisperse colloids of conjugated polymers in high yields. Here, a recently developed Suzuki–Miyaura dispersion polymerization method is adopted to synthesize core–shell particles, in which a conjugated polymer shell is grown onto non-conjugated organic and inorganic colloidal templates. By chemically anchoring aryl halide groups at the particle surface, a conjugated polymer shell can be attached to a wide variety of organic and inorganic microparticles. In this way, both spherical and non-spherical hybrid conjugated polymer particles are prepared, and it is shown that the method can be applied to a variety of conjugated polymers. This new method offers independent control of the size, shape and photophysical properties of these novel conjugated polymer particles.

Fabrication of monodisperse anisotropic silica hollow microspheres using polymeric cave particles as templates

Monodisperse anisotropic poly(styrene-co-divinylbenzene) (PS-DVB) particles with single cavity structures were synthesized using a modified dispersion polymerization method. The effects of DVB adding modes and speeds on the particle morphologies were studied. Using the PS-DVB cave particles as templates, monodisperse anisotropic silica (SiO2) hollow microspheres were fabricated facilely. The obtained anisotropic silica hollow spheres had a potential application in rapid waste removal and detoxification extraction with a very simple procedure.

Preparation and characterization of chemically synthesized polyaniline–polystyrene blends as a carbon dioxide gas sensor

This correspondence presents a radically distinctive approach for preparing conducting polymer polyaniline–polystyrene (PANI–PS) blends doped with HCl by an in situ dispersion polymerization method. Generally, there are two prerequisites for choosing the blended polymers: good compatibility with PS molecules and comparatively high electrical conductivity. Therefore, we use different monomer ratios of PS keeping the aniline concentration constant while preparing the five blends. The blend films, cast on glass substrates, are characterized by various studies such as SEM (for morphology), XRD (for crystallinity), FTIR chemical interaction, DSC, and TGA thermal properties. Subsequently, the electrical properties are studied using I–V characteristics and four probe conductivity measurements. The SEM results of the above polymerized blends reflect the formation of spherical nanoparticles with diameter ranging from 50nm to 90nm with a decrease in PS concentration that facilitates the formation of clusters. Furthermore, the XRD diffractograms show semi crystalline behavior of the blend films where crystallinity decreases with decreasing PS concentration. The FTIR spectra establish a new peak in the blend films other than the peaks found in PANI and PS films indicating possible chemical crosslinking between the polymers. It can be observed that the increase in PS concentration increases the intensity of the peak. The TGA of the polymer blends reveals five-step degradation including four due to the pure polymer and one due to the blend formation. The decomposition temperature is found to be more for blend film than that of pure PANI but less than PS decomposition. The DSC results display a peak, each for water and oxidation of the polymer blend, but do not contain any such for PANI. From DSC data, it is clear that the blend film exhibits the combined physical properties of both the polymer components. The non-ohmic behavior of I–V characteristics by the blend films indicates that these nanocomposite films may have some utility in electronic device applications; an increase in conductivity is observed with decreasing PS concentration. Finally, the blend films with high conductivity seem to have good sensitivity and reversibility when used as CO2 sensors.

Synthesis of polyethylenimine-functionalized poly(glycidyl methacrylate) magnetic microspheres and their excellent Cr(VI) ion removal properties

Micron-sized polyethylenimine-functionalized poly(glycidyl methacrylate) superparamagnetic microspheres (m-PGMA-PEI) were prepared by a process involving: (1) synthesis of PGMA microspheres using the dispersion polymerization method; (2) ring-opening reaction of epoxy groups on PGMA microspheres with ethylenediamine (EDA) to yield amino groups; (3) in situ coprecipitation of Fe3O4 nanoparticles into the pores of microspheres; (4) Michael addition of amino groups with methyl acrylate (MA) to yield ester groups; and (5) amidation of the terminal ester groups with polyethylenimine (PEI). Once generated, the resulting m-PGMA-PEI microspheres were tested for their ability to remove Cr(VI) from an aqueous solution in batch experiments. The results demonstrated that Cr(VI) adsorption was significantly pH dependent. The optimized pH value was 2.0. The adsorption isotherm of the adsorbent fit the Langmuir model, with the maximum adsorption capacity of 492.61mg/g. The Cr(VI) adsorption rate was rapid, and the adsorption reached equilibrium within 15min. The thermodynamic parameters (ΔG0, ΔH0, ΔS0) demonstrated that the adsorption process was endothermic and spontaneous in nature. The presence of the coexisting anions involving Cl−, NO3-, H2PO4- and HPO42- had no remarkable influence on Cr(VI) adsorption except SO42-. The regeneration study proved that the m-PGMA-PEI microspheres could be repeatedly utilized with no significant loss of adsorption efficiency.

EXTRACTION OF SHIKIMIC ACID FROM CHINESE STAR ANISE USING FLASH COLUMN CHROMATOGRAPHY ON A MOLECULARLY-IMPRINTED POLYMER COLUMN

Flash column chromatography prepacked with molecularly imprinted polymers (MIPs) has been successfully used for the extraction of shikimic acid from Chinese star anise. The shikimic acid imprinted polymer with an adsorption capacity of 21.94 µmol g−1 dry polymer and imprinting factor of 4.2 was prepared using the dispersion polymerization method. The capacity of the MIP-Flash column was determined as 23.3 mg g−1 using a frontal chromatography method when 10 m mol L−1 shikimic acid was eluted through the MIP-flash column at 1.7 mL min−1. The crude extract of Chinese star anise loaded on the column was eluted with ethanol/water (40/60, v/v) to remove the impurities, after elution with methanol/water/acetic acid (32/48/20, v/v/v), purified shikimic acid (>95%) was obtained. The MIP-flash column can be reused for at least 4 rounds with capacity lost less than 15%. It was demonstrated that, compared with HPLC, flash column chromatography prepacked with MIPs is a more rapid, feasible, and economical method for the extraction of active ingredients from plants on a large scale based on the technology of molecular imprinting.

Preparation and drug-loading properties of Fe3O4/Poly(styrene-co-acrylic acid) magnetic polymer nanocomposites

Fe3O4/poly(styrene-co-acrylic acid) magnetic polymer nanocomposites were synthesized by the dispersion polymerization method using styrene as hard monomer, acrylic acid as functional monomer, Fe3O4 nanoparticles modified with oleic acid as core, and poly(styrene-co-acrylic acid) as shell. Drug-loading properties of magnetic polymer nanocomposites with curcumin as a model drug were also studied. The results indicated that magnetic polymer nanocomposites with monodisperse were obtained, the particle size distribution was 50–120nm, and the average size was about 100nm. The contents of poly(styrene-co-acrylic acid) and Fe3O4 nanoparticles in magnetic polymer nanocomposites were 74％ and 24.7％, respectively. The drug-loading capacity and entrapment efficiency were 2.5% and 44.4%, respectively. The saturation magnetization of magnetic polymer nanocomposites at 300K was 20.2emu/g without coercivity and remanence. The as-prepared magnetic polymer nanocomposites have not only lots of functional carboxyl groups but also stronger magnetic response, which might have potential applications in drug carrier and targeted drug release.