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Dispersion Polymerization (dispersion + polymerization)

Distribution by Scientific Domains

Polymers and Materials Science	96%

Selected Abstracts

Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic Media

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2006
Muhammad Mumtaz
Abstract Summary: The synthesis of PEDOT nanoparticles and vesicles by dispersion polymerization in a methanol/water mixture (3/2, v/v) is reported, using either ammonium persulfate or iron(III) p -toluenesulfonate as oxidants and , -EDOT-PEO as a reactive stabilizer. The influence of the oxidant as well as the , -EDOT-PEO molar mass and concentration on the core-shell particle morphology and conductivity properties have been investigated. PEDOT particles with conductivities up to 1.5,×,10,2 S,·,cm,1 have been obtained in high yield. TEM image of PEDOT vesicles prepared using PEO-based stabilizers of 25,000 g,·,mol,1 in water/methanol mixture (2:3 v/v) at room temperature using ammonium persulfate as an oxidant. [source]

RAFT Synthesis of Sterically Stabilized Methacrylic Nanolatexes and Vesicles by Aqueous Dispersion Polymerization,

ANGEWANDTE CHEMIE, Issue 24 2010
Yuting Li Dr.
Größenkontrolliert: Sterisch stabilisierte Methacrylat-Nanolatices sind durch wässrige Dispersionspolymerisation unter Anwendung von RAFT-Techniken zugänglich (siehe Schema; CTA = Kettentransferreagens). Die Größe der Partikel kann über die Länge der Poly(HPMA)-Ketten präzise eingestellt werden. [source]

Non-Fluorous Random Copolymeric Stabilizers for Dispersion Polymerizations of MMA in Supercritical CO2

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 9 2006
Ha Soo Hwang
Abstract Summary: The dispersion polymerization of MMA in supercritical CO2 was successfully carried out utilizing the first non-fluorous random copolymers composed of 3-tris(trimethoxysilyl)propyl methacrylate and 2-dimethylaminoethyl methacrylate, poly(SiMA- co -DMAEMA) as a stabilizer. The resulting high yield (>93%) of micron-sized PMMA was formed in the presence of 5% (w/w to MMA) of copolymeric stabilizers. While the PSiMA and PDMAEMA homopolymer produced nondescript solid and irregular shape aggregate, respectively, the random copolymer of 71% SiMA-content resulted in spherical and uniform powder. SEM image of PMMA particles prepared in supercritical CO2 using poly(SiMA- co -DMAEMA) (71:29) stabilizer. [source]

Dispersion polymerization of methyl methacrylate: Effect of stabilizer concentration

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008
Sheng Jiang
Abstract In dispersion polymerizations of methyl methacrylate (MMA), little difference was found in the polymerization kinetics with varying stabilizer (PVP K-30) concentration, indicating that in contrast to emulsion polymerization, the kinetics of these dispersion polymerizations are independent of the number of particles. Comparing MMA precipitation and dispersion polymerizations revealed that nuclei formation in the latter results from precipitation polymerization occurring in the continuous phase, which can contribute significantly to the kinetics, and especially to the molecular weight distributions. No change was found in the molecular weight distribution of the PVP during a dispersion polymerization, nor was there any measurable difference between using fresh and recycled stabilizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Dispersion polymerization of vinyl monomers in supercritical carbon dioxide in the presence of drug molecules: A one-pot route for the preparation of controlled delivery systems

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2008
Alessandro Galia
Abstract The polymerization of 1-vinyl-2-pyrrolidone in supercritical carbon dioxide in the presence of ibuprofen as a model drug was investigated as a new one-pot process for the preparation of polymer-based drug delivery systems (DDSs). The composites were prepared at 65 °C and P = 31,42 MPa by changing the initial concentration of the drug and the concentration of a crosslinking agent and that of a hydrophobic comonomer. The effects of these parameters on the performances of the polymerization and on the in vitro release kinetics of ibuprofen were studied. In all the experiments, part of the drug was entrapped inside the polymer particles and dissolved more slowly with respect to the pure compound. Copolymerization with methyl methacrylate was the most effective route to obtain a DDS with sustained temporal release of the drug molecule. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7429,7446, 2008 [source]

Dispersion polymerization of styrene in carbon dioxide stabilized by copolymers of poly(propylene glycol) methacrylate and 2-(perfluorooctyl)ethyl methacrylate

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2003
Lunhan Ding
Abstract The dispersion polymerization of styrene in carbon dioxide with a series of copolymers of poly(propylene glycol) methacrylate (PPGMA) and 2-(perfluorooctyl)ethyl methacrylate (FOEMA) as the polymerization dispersants was examined. It was demonstrated that PPGMA and FOEMA copolymers and polymers containing 52,100% FOEMA could be used as effective dispersants for the polymerization, and the composition of the copolymeric dispersant had a dramatic effect on both the polymerization yield and the morphology of the resulting polystyrene. The effects of the concentrations of the copolymeric dispersants, the concentrations of the monomer, and the reaction pressure were also investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3804,3815, 2003 [source]

Encapsulated-Dye All-Organic Charged Colored Ink Nanoparticles for Electrophoretic Image Display

ADVANCED MATERIALS, Issue 48 2009
Sun Wha Oh
Electrophoretic ink nanoparticles with high mobility are successfully fabricated by dispersion polymerization. The color of test cells can be changed by applying a bias voltage, as shown in the figure: the lower row shows the same cells as the upper row but with an applied voltage. These all-organic, encapsulated-dye, electrophoretic ink particles are expected to reduce the fabrication cost of e-ink in electrophoretic image display cells. [source]

Fabrication of Polypyrrole, Poly(N -vinylcarbazole) Core,Shell Nanoparticles with Excellent Electrical and Optical Properties,

ADVANCED MATERIALS, Issue 11 2005
J. Jang
Polypyrrole,poly(N -vinylcarbazole) (PPy,PVK) core,shell nanoparticles have been fabricated by nanoparticle-seeded dispersion polymerization. The monodisperse PPy nanoseeds are fabricated by micelle templating, and the PVK shell thickness is easily tuned by varying the amount of N -vinylcarbazole monomer. The PPy core and PVK shell produce superior conductivity and fluorescence, respectively (see Figure). [source]

Polymerization of methyl methacrylate in the presence of a nonpolar hydrocarbon solvent.

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010

Abstract This article presents the ternary phase diagram for methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), and n -hexane system at 70°C. It was constructed by both theoretical calculations and online laser light scattering (LLS) technique. In situ polymerization of MMA in a nonpolar nonsolvent carried out in a LLS cell provides a new means for the accurate detection of the cloud points of highly viscous polymer mixtures, with polymer weight fractions over 0.6. The ternary phase diagram measured in this study can be used to design the reaction conditions for the precipitation and/or dispersion polymerization in a nonpolar nonsolvent medium where polymerization kinetics as well as polymer particle morphologies are strongly affected by thermodynamic phase separation phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Synthesis by a single-step swelling process and characterization of micrometer-sized polychloromethylstyrene/poly(butyl methacrylate) hemispherical composite particles of narrow size distribution

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008
Sigal Baruch-Sharon
Abstract Polychloromethylstyrene (PCMS) micrometer-sized particles of narrow size distribution were prepared by the dispersion polymerization of chloromethylstyrene in a mixture of ethanol and dimethyl sulfoxide. Micrometer-sized PCMS/poly(butyl methacrylate) hemispherical composite particles of narrow size distribution were prepared by a single-step swelling process of the uniform PCMS template particles with emulsion droplets of butyl methacrylate (BMA) containing benzoyl peroxide, followed by the polymerization of BMA at 73°C within the swollen template particles. The effects of various polymerization parameters, for example, BMA volume, initiator type and concentration, and toluene as the swelling solvent, on the properties (size and size distribution, morphology, polymerization yield, and composition) of the hemispherical composite particles were elucidated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Dispersion polymerization of methyl methacrylate: Effect of stabilizer concentration

FTIR, 1H-NMR spectra, and thermal characterization of water-based polyurethane/acrylic hybrids

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008
O. R. Pardini
Abstract Polyurethane (PU) polymer was synthesized following a prepolymer mixing process, by polyaddition of isophorone diisocyanate (IPDI), poly(propylene glycol) (PPG), 2-hydroxyethyl methacrylate (HEMA), and 2,2-bis(hydroxymethyl)propionic acid (DMPA). The PU anionomer having 2-ethoxymethacrylate terminal groups was dispersed in water by prior neutralization of carboxylic acid groups of DMPA with triethylamine (TEA), chain extended with hydrazine (HZM) in water and a dispersion polymerization with methyl methacrylate/n -butyl acrylate/acrylic acid mixture was performed. The above polymerization reactions lead to the formation of PU/acrylic hybrids having a chemical bond between PU and acrylic moieties. Acrylic content was varied from 0 to 50 wt % and samples were purified to eliminate oligomers and impurities before characterization. The FTIR and 1H-NMR spectra of these purified hybrid samples were obtained and bands and peaks assignments were discussed. Thermal properties (DSC and TGA) were also discussed. Breaking hydrogen bonds is the main reason for changes in properties with increasing acrylic content. Particle size data of dispersions is also presented and discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Preparation of normal-phase HPLC stationary phase based on monodisperse hydrophilic polymeric beads and their application

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
Bolin Gong
Abstract The monodisperse, 5.0 ,m hydrophilic macroporous poly(glycidymethacrylate- co -ethylenedimethacrylate) beads were first prepared based on monosized linear poly(glycidylmethacrylate) beads as seed by using a single-step swelling and polymerization method. The seed beads prepared by dispersion polymerization exhibited good absorption of the monomer phase. The pore size distribution of the beads was evaluated by mercury instrusion method. The surface area was calculated from the BET isotherms of nitrogen adsorption and desorption. The beads were modified to be a normal-phase liquid chromatographic (NPLC) stationary phase for high performance liquid chromatography (HPLC) in the following steps. First, the beads were completely hydrolyzed. Second, hydrolyzed particles were reacted with epichlorihydrin followed by another hydrolysis of the newly introduced epoxide groups. The retention properties of the NPLC stationary phase were easily modulated by changes in the composition of the mobile phase. The performance of theses beads was demonstrated with the separation of a variety of polar compounds. The satisfactory results were obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Controlled/living heterogeneous radical polymerization in supercritical carbon dioxide

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2009
Per B. Zetterlund
Abstract Supercritical carbon dioxide (scCO2) is an inexpensive and environmentally friendly medium for radical polymerizations. ScCO2 is suited for heterogeneous controlled/living radical polymerizations (CLRPs), since the monomer, initiator, and control reagents (nitroxide, etc.) are soluble, but the polymer formed is insoluble beyond a critical degree of polymerization (Jcrit). The precipitated polymer can continue growing in (only) the particle phase giving living polymer of controlled well-defined microstructure. The addition of a colloidal stabilizer gives a dispersion polymerization with well-defined colloidal particles being formed. In recent years, nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP), and reversible addition fragmentation chain transfer (RAFT) polymerization have all been conducted as heterogeneous polymerizations in scCO2. This Highlight reviews this recent body of work, and describes the unique characteristics of scCO2 that allows composite particle formation of unique morphology to be achieved. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3711,3728, 2009 [source]

Synthesis of stimuli-responsive macroazoinitiators and their use as an inistab toward hairy polymer latex particles

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2009
Syuji Fujii
Abstract Stimuli-responsive macroazoinitiators with central azo unit have been synthesized by atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate or 2-(diethylamino)ethyl methacrylate in 2-propanol at 25 °C. The mean degree of polymerization of the polymer chains besides the azo group was fixed between 25 and 60. 1H NMR, gel permeation chromatography, UV-Vis spectrophotometer, and surface tensiometer were used to characterize the stimuli-responsive macroazoinitiators in terms of their chemical structure, molecular weight, polydispersity, and pH-responsive behavior, respectively. Eventually, dispersion polymerization of styrene using the poly[2-(diethylamino)ethyl methacrylate] (PDEA) macroazoinitiator as an inistab (initiator + stabilizer) in 2-propanol medium was conducted. Near-monodisperse 98 nm polystyrene (PS) latex particles with pH-responsive PDEA hair were successfully synthesized. The PS latex particles with the PDEA hair can be dispersed in acidic aqueous media where the PDEA hair was protonated and was solvated, and can be flocculated in basic aqueous media where the PDEA hair was deprotonated and was precipitated. This dispersion-flocculation cycle was reversible. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3431,3443, 2009 [source]

A direct preparation of silica shell on polystyrene microspheres prepared by dispersion polymerization with polyvinylpyrrolidone

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2008
Jinho Hong
PS/silica core/shell structured microspheres were easily prepared in a simple process. Because of the acid-base interaction between the TEOS and seed particles prepared by dispersion polymerization, uniform silica shell was formed on the PVP-stabilized PS particles without additional PVP-coating process. [source]

Photoinitiated dispersion polymerization of methyl methacrylate: A quick approach to prepare polymer microspheres with narrow size distribution

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2008
Jia Chen
Abstract Photoinitiated dispersion polymerization of methyl methacrylate was carried out in a mixture of ethanol and water as dispersion medium in the presence of poly(N -vinylpyrrolidone) (PVP) as the steric stabilizer and Darocur 1173 as photoinitiator. 93.7% of conversion was achieved within 30 min of UV irradiation at room temperature, and microspheres with 0.94 ,m number,average diameter and 1.04 polydispersity index (PDI) were obtained. X-ray photoelectron spectroscope (XPS) analysis revealed that only parts of surface of the microspheres were covered by PVP. The particle size decreased from 2.34 to 0.98 ,m as the concentration of PVP stabilizer increased from 2 to 15%. Extra stabilizer (higher than 15%) has no effect on the particle size and distribution. Increasing medium polarity or decreasing monomer and photoinitiator concentration resulted in a decrease in the particle size. Solvency of reaction medium toward stabilizer, which affects the adsorption of stabilizer on the particle surface, was shown to be crucial for controlling particle size and uniformity because of the high reaction rate in photoinitiated dispersion polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1329,1338, 2008 [source]

Stabilizer-free dispersion copolymerization of maleic anhydride and vinyl acetate.

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005

Abstract A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer-free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT-IR and 13C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge-transfer-complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n -butyl acetate, isobutyl acetate, n -amyl acetate, are desirably fit for this unique stabilizer-free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760,3770, 2005 [source]

High molecular weight monodisperse polystyrene microspheres prepared by dispersion polymerization, using a novel bifunctional macromonomer

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2005
Hyejun Jung
Abstract A novel bifunctional vinyl-terminated polyurethane macromonomer was applied to the dispersion polymerization of styrene in ethanol. Monodisperse polystyrene (PS) microspheres were successfully obtained above 15 wt % of macromonomer relative to styrene. The steep slope from the reduction of the average particle size reveals that the macromonomer can efficiently stabilize higher surface area of the particles when compared with a conventional stabilizer, poly(N -vinylpyrrolidone). The stable and monodisperse PS microspheres having the weight-average diameter of 1.2 ,m and a good uniformity of 1.01 were obtained with 20 wt % polyurethane macromonomer. The grafting ratio of the PS calculated from 1H NMR spectra linearly increased up to 0.048 with 20 wt % of the macromonomer. In addition, the high molecular weights (501,300 g/mol) of PS with increased glass transition and enhanced thermal degradation temperature were obtained. Thus, these results suggest that the bifunctional vinyl-terminated polyurethane macromonomer acts as a reactive stabilizer, which gives polyurethane-grafted PS with a high molecular weight. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3566,3573, 2005 [source]

Nonaqueous dispersion polymerization of styrene in methanol with the ionomer block copolymer poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)]- b -polyisobutene as a stabilizer

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2004
Yuhong Ma
Abstract The nonaqueous dispersion polymerization of styrene in methanol with poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)]- b -polyisobutene as a stabilizer was investigated. There was no observable inducing period or autoacceleration in the polymerization process. The conversion increased almost linearly with the polymerization time as high as 80%. The average sizes of the obtained polystyrene particles increased, and the size distributions of the polystyrene particles tended to become narrower, with increasing conversion. The mechanism of the dispersion polymerization in the presence of polyisobutene- b -poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)] was nucleation/growth. When the stabilizer/monomer ratio (w/w) was greater than 2.0%, the polystyrene dispersion was stable, and there was no observable polymer particle coagulation taking place during the whole polymerization process. The average diameter of the polymer particles can be mediated through changes in the polymerization conversion, monomer, and stabilizer. Nearly monodispersed polystyrene particles with average diameters of approximately 0.45,2.21 ,m were obtained under optimal conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2678,2685, 2004 [source]

Synthesis of highly crosslinked monodisperse polymer particles: Effect of reaction parameters on the size and size distribution

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2002
J. Choi
Abstract Monodisperse polystyrene particles crosslinked with different concentrations of divinylbenzene were synthesized in the 3.2,9.1 ,m size range by dispersion polymerization in an isopropyl alcohol/toluene mixed-dispersion medium with poly(N -vinylpyrrolidone) as a steric stabilizer and 2,2,-azobisisobutyronitrile as a radical initiator. The effects of the reaction parameters such as the crosslinking agent concentration, media solvency (controlled by varying the amount of toluene addition), the initiator concentration, and the stabilizer concentration on the particle size and size distribution were investigated with reference particles with a monodisperse size distribution and crosslinked by 1.5 wt % divinylbenzene. The appropriate increase in media solvency was a prerequisite for preparing crosslinked particles without coagulated and/or odd-shaped particles. The investigation of the effects of the polymerization parameters also shows that only specific sets of conditions produce particles with a monodisperse size distribution. The glass-transition temperatures of the particles increased with increasing divinylbenzene concentration. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4368,4377, 2002 [source]

Novel Light Emitting Diode Using Organic Electroluminescence Microcapsules

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2003
Jae-Seok Heo
Abstract Novel light emitting diodes (LEDs) were prepared using electroluminescence (EL) material/polymer microcapsules (ELC). N-vinylcarbazole as a hole-transporting component and methyl methacrylate (MMA) were copolymerized for producing the seed particles using dispersion polymerization. An oxadiazole derivative, synthesized as a electron-transporting component, and tris(8-hydroxyquinolinato) aluminium(III) (Alq3) were incorporated into the polymer particles by using the solute co-diffusion method (SCM). The LEDs for the EL characterization were fabricated in a thin sandwich configuration: Al anode/ELC/ITO cathode. The surface imaging of the LED prepared using ELC was performed by atomic force microscopy (AFM). The EL characteristics of the ELC were investigated by UV, photoelectron and luminescence spectroscopy, and the current-voltage and the light-voltage characteristics for the LED were determined. Encapsulation procedure using solute co-diffusion method (SCM). [source]

Preparation of Polystyrene/Clay Nanocomposites by Free-Radical Polymerization in Dispersion

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2009
Nagi Greesh
Abstract Fully exfoliated PS/clay nanocomposites were prepared via FRP in dispersion. Na-MMT clay was pre-modified using MPTMS before being used in a dispersion polymerization process. The objective of this study was to determine the impact of the clay concentrations on the monomer conversion, the polymer molecular weight, and the morphology and thermal stability of the nanocomposites prepared via dispersion polymerization. DLS and SEM revealed that the particle size decreased and became more uniformly distributed with increasing clay loading. XRD and TEM revealed that nanocomposites at low clay loading yielded exfoliated structures, while intercalated structures were obtained at higher clay loading. [source]

Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic Media

A Novel, Facile Method for the Preparation of Uniform, Reactive Maleic Anhydride/Vinyl Acetate Copolymer Micro- and Nanospheres

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2004
Chang-Min Xing
Abstract Summary: A novel, stabilizer-free dispersion polymerization with alkyl esters as reaction media gives uniform alternating microspheres of maleic anhydride (MAn)/vinyl acetate (VAc) copolymer. The diameter of the copolymer microspheres could be precisely controlled from 80 to 750 nm by changing the monomer concentration or feed ratio. Moreover, this new type of copolymer microspheres with reactive anhydride groups on the surface has good solubility in common nontoxic solvents such as water and ethanol. SEM image of the powder surface of copolymer microspheres formed at [MAn],=,[VAc],=,1.5 M. [source]

A Comparison of Modeling Approaches for Dispersion Homopolymerization of MMA and Styrene in Supercritical CO2

MACROMOLECULAR REACTION ENGINEERING, Issue 4 2008
Iraís A. Quintero-Ortega
Abstract A comparison of kinetic models for dispersion polymerization of MMA and styrene in supercritical CO2 is presented. The limiting case of solution polymerization, as a simplified case, was also addressed. Calculation of the partition of components between the continuous and dispersed phases was emphasized. Experimental data for the solution and dispersion polymerizations of styrene and MMA, using different types of stabilizers, were used to guide the study. Although all the models analyzed can be considered as "adequate" in representing the behavior of the system, some of their strengths and drawbacks have been highlighted. [source]

Synthesis and characterization of dual-responsive micrometer-sized core-shell composite polymer particles

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008
M. Ashraful Alam
Abstract Dual-responsive micrometer-sized core-shell composite polymer particles were prepared by dispersion polymerization followed by seeded copolymerization. Polystyrene (PS) particles prepared by dispersion polymerization were used as core particles. N-isopropyl acrylamide (NIPAM) and methacrylic acid (MAA) were used to induce dual-responsive that is thermo- and pH-responsive properties in the shell layer of composite polymer particles, prepared by seeded copolymerization with PS core particles. Temperature- and pH-dependent adsorption behaviors of some macromolecules on composite polymer particles indicate that produced composite polymer particles exhibit dual-responsive surface properties. Copyright © 2007 John Wiley & Sons, Ltd. [source]