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1.
Hullathy Subban Ganapathy Jun Ho Kim Won Soo Kim Min Hee Woo Min Young Lee Seung-Soo Hong Hyun Gyu Kim Euh Duck Jeong Kwon Taek Lim 《Colloid and polymer science》2008,286(6-7):843-848
To overcome the environmental concerns associated with long-chain perfluorinated compounds, in this report, non-bioaccumulative, environmentally friendly stabilizer architectures based on short-chain fluorinated polymers have been designed for the dispersion polymerization of methyl methacrylate (MMA) in supercritical CO2. Random copolymers composed of 2-(diisopropylamino)ethyl methacrylate (DPAEMA) and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (FBMA) or 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate were prepared with various comonomer ratios and utilized as stabilizers. It was found that the copolymers effectively stabilized PMMA latexes in CO2, leading to the formation of free-flowing, spherical PMMA particles. With increase in the concentration of the stabilizer poly(FBMA-co-DPAEMA) from 2% to 6% (w/w with respected to MMA), the particles diameter decreased from 3.02 to 1.0 μm. 相似文献
2.
Ha Soo Hwang Haldorai Yuvaraj Won Soo Kim Won‐Ki Lee Yeong‐Soon Gal Kwon Taek Lim 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1365-1375
A series of random copolymers, composed of 1H,1H‐perfluorooctyl methacrylate (FOMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) were prepared as stabilizers for the dispersion polymerization of methyl methacrylate in supercritical CO2 (scCO2). Free‐flowing, spherical poly(methyl methacrylate) (PMMA) particles were produced in high yield by the effective stabilization of poly(FOMA‐co‐DMAEMA) containing 34–67 w/w % (15–41 m/m %) FOMA structural units. Less stabilized but micron‐sized discrete particles could be obtained even with 25 w/w % (10 m/m %) FOMA stabilizer. The result showed that the composition of copolymeric stabilizers had a dramatic effect on the size and morphology of PMMA. The particle size was controllable with the surfactant concentration. The effect of the monomer concentration and the initial pressure on the polymerization was also investigated. The dry polymer powder obtained from dispersion polymerization could be redispersed to form stable aqueous latexes in an acidic buffered solution (pH = 2.1) by an electrostatic stabilization mechanism due to the ionization of DMAEMA units in the stabilizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1365–1375, 2008 相似文献
3.
Shuhei Yamada Zhifeng Wang Emiko Mouri Kohji Yoshinaga 《Colloid and polymer science》2009,287(2):139-146
We report a novel strategy for incorporation of titanium dioxide (TiO2) particles, which were crystallized from peroxotitanic acid in the presence of hydrophilic polymer by hydrothermal treatment
in aqueous solution, into poly(methyl methacrylate) (PMMA) via dispersion into chloroform. Dispersion of TiO2 particles into chloroform was achieved by solvent change from water to chloroform in aid of amphiphilic polymer dispersant,
poly(N-vinyl pyrrolidone) (PVP), poly(N-vinyl pyrrolidone-co-methyl methacrylate) (PVP-co-PMMA), poly(N-vinyl pyrrolidone-block-methyl methacrylate) (PVP-b-PMMA) through azeotropical removal of water. Incorporation of TiO2 particles into PMMA was carried out by a casting process of a mixture of TiO2 particles dispersed with PVP154-b-PMMA156 in chloroform and PMMA on a glass substrate. Resultant hybrid film containing TiO2 less than 10 wt.% showed high transparency in visible region attributable to homogeneous dispersion into PMMA matrix. The
refractive index of the hybrid films increased with TiO2 content and agreed with the calculated values. 相似文献
4.
In a dispersion polymerization, the monomer is miscible with the reaction medium, while the resulting polymer is insoluble under the same conditions. The macroscopic precipitation of the polymer is prevented by a steric stabilizer. Methyl methacrylate was polymerized in decane in presence of polystyrene-block-poly(ethylene-co-propylene) and spherical dispersion particles of poly(methyl methacrylate) (PMMA) were obtained. The static light scattering yielded molar masses of particles in the range 4 × 107 to 7 × 109 g mol−1. Dynamic light scattering provided the hydrodynamic radii from 60 to 190 nm and also information on the non-uniformity of the particles. The relations between the characteristics of the dispersion particles (concentration of components, particle mass and dimensions, molar mass of PMMA chains, surface density of stabilizing chains, etc.) were looked for. The kinetics of polymerization seems to be only little affected by the colloidal character of the system. 相似文献
5.
Ha Soo Hwang Yeong‐Soon Gal Keith P. Johnston Kwon Taek Lim 《Macromolecular rapid communications》2006,27(2):121-125
Summary: Statistical random copolymers of 1H,1H‐perfluorooctyl methacrylate and 2‐dimethylaminoethyl methacrylate, poly(FOMA‐co‐DMAEMA), effectively stabilized the dispersion polymerization of methyl methacrylate in supercritical carbon dioxide. Free‐flowing, micron‐sized spherical PMMA particles could be produced with poly(FOMA‐co‐DMAEMA) containing 34 w/w% FOMA.
6.
Nil Baran 《European Polymer Journal》2005,41(5):1159-1167
The free radical dispersion polymerization of styrene was carried out in supercritical carbon dioxide (scCO2) using two different stabilizers. The polymerizations are performed in the presence of poly(heptadecafluorodecyl acrylate-co-tris(trimethylsilyloxy)silyllpropyl methacrylate) p(HDFDA-co-SiMA) and a commercially available carboxylic acid-terminated perfluoropolyether (Krytox® 157FSL) as polymerization stabilizers. Dry, fine powdered spherical polystyrene particles were produced under optimised conditions. The resulting high yield of spherical and relatively uniform micron-size polystyrene particles were formed utilizing various amounts of p(HDFDA-co-SiMA) random copolymer. However, it was observed that Krytox® 157FSL was not a good stabilizer as p(HDFDA-co-SiMA) for the dispersion polymerization of styrene. The particle diameter was shown to be dependent on the type of the stabilizer and the weight percent of the stabilizer added to the system. The effect of varying the concentrations of stabilizers and initiator, reaction time and reaction pressure upon the polymerization yield, molar mass and morphology of polystyrene have been investigated. 相似文献
7.
Cationic poly(styrene-co-N,N-dimethylaminoethyl methacrylate) (P(St-co-DMAEMA)) latexes were prepared in the absence of surfactant by using 2,2’ -azobis (2-methylpropionamidine) dihydrochloride (AIBA) as the initiator. The effects of the AIBA concentration, HCl/DMAEMA molar ratio and DMAEMA amount on the emulsion polymerization and the latex properties were investigated. The particle morphology and size, the zeta potential and the amino distribution of the P(St-co-DMAEMA) latexes were characterized by transmission electron microscope (TEM), dynamic light scattering (DLS) and conductometric titration, respectively. Results showed that the emulsion polymerization performed smoothly with high monomer conversion and narrow particle size distribution under the optimized conditions with AIBA concentration of 1 wt%, HCl/DMAEMA molar ratio of 1.2 and DMAEMA content of 5 wt%. The diameter of the dried latex particles decreased and the density of amino groups on the particle surfaces increased with increasing the DMAEMA content. The zeta potential of the P(St-co-DMAEMA) latexes was pH-dependent and the zero point was around at pH 7.2. A facile method was developed to fabricate P(St-co-DMAEMA)/laponite hybrid nanoparticles via electrostatic adsorption, in which the loading capacity of laponite platelets reached 17.7 wt%, and the resultant hybrid nanoparticles showed good thermal stability. 相似文献
8.
Kohji Yoshinaga Suguru Motokucho Ken Kojio Akemi Nakai 《Colloid and polymer science》2012,290(12):1221-1226
Dispersion of fullerene, C60, by addition of polymethacrylate dispersant in methyl methacrylate (MMA) and incorporation of C60 into poly(methyl methacrylate) (PMMA) were investigated. Copolymers synthesized by radical copolymerization of MMA and 2-naphthyl methacrylate (NMA), poly(MMA-co-NMA), effectively dispersed C60 in MMA to form clusters of 20?nm. In these cases, addition of minimal 110 naphthyl groups per unit C60 molecule afforded to give clusters with minimum of 20?nm sizes. Furthermore, block copolymers, poly(MMA-b-NMA) with MMA/NMA mole ratio from 12:1 to 20:1, also efficiently dispersed C60 to give formation of clusters of 20?nm size by addition of minimal 40 naphthyl groups per unit C60 molecule, which was corresponding to approximate nine layers of naphthyl group in block copolymer adsorbed on the surface of the cluster. Hybrid films of C60/PMMA, prepared by casting of C60-dispersed solution containing PMMA, exhibited absorbance at 400?nm linearly increased with C60 content. 相似文献
9.
10.
Mohammad Reza Shahsavari Alireza Namjoo Hossein Mohammadian Younes Saadat Soleyman Hosseinzadeh Samira Abdolbaghi 《Colloid Journal》2016,78(3):415-424
Dual-seeded dispersion polymerization (DSDP) of 2-ethylhexyl methacrylate with polystyrene (PS) and poly(methyl methacrylate) (PMMA) seed beads in the presence of saturated hydrocarbon droplets followed by evaporation of the hydrocarbon was studied. The effect of various polymerization conditions including initiator type and content, stabilizer type and concentration, and different hydrocarbon’s content on the shape of the obtained particles was investigated. The increase of concentration of 2,2'-azobis(isobutyronitrile) (AIBN) had no effect on the shape of the produced almond-shell-like PS particles, although it contributes in the formation of associated composite particles along with larger poly(2-ethylhexyl methacrylate) (PEHMA) beads produced by secondary nucleation. The experimental results showed that other initiators led to the formation of stable golf-ball-like PMMA particles as well as PS ones with symmetric shape. The type of stabilizer did not affect the shape of the particles. This observation suggests that unique almond-shelllike PS particles can be produced through a stabilizer-free DSDP process. The lowering of the concentration of hydrocarbons with long alkyl chains yielded stable disc-like PMMA particles. The formation of functional almond-shell-like particles by using light hydrocarbons was another interesting finding of this research. 相似文献
11.
Sung‐Young Park Hee‐Young Park Hwa‐Soo Lee Sang‐Wook Park Chang‐Sik Ha Dae‐Won Park 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1472-1480
This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001 相似文献
12.
Abstract Seed dispersion polymerization of methyl methacrylate (MMA) in the presence of monodisperse PMMA particles was carried out in an aqueous methanol using poly(methacrylic acid) stabilizer. The polymerization using 2. 5 μ. m-sized seed particles gave monodisperse PMMA particles in the diameter up to 4. 9 μm. The solvent composition and monomer concentration greatly affected the polymerization behavior. Under appropriate conditions, monodisperse PMMA particles in the diameter up to 8. 9 μ, m was prepared from 4. 6 μm-sized seed particles. The seed dispersion polymerization of styrene in the presence of the seed particles produced monodisperse PMMA-polystyrene particles in the micron range. The particles were supposed to have a structure consisting of PMMA-core and polystyrene-shell from ESCA analysis. 相似文献
13.
Masahiro Fujioka Guang‐Hui Ma Yong‐Zhong Du Kenji Ogino Masatoshi Nagai Shinzo Omi 《Journal of polymer science. Part A, Polymer chemistry》2003,41(12):1788-1798
The poly(HEMA‐co‐MMA‐g‐PMMA) graft copolymer was prepared with a poly(methyl methacrylate) (PMMA) macromonomer, 2‐hydroxyethyl methacrylate (HEMA), and methyl methacrylate (MMA), and its application as a dispersant for the nonaqueous phase dispersion polymerization of polystyrene (PST) was investigated. Monodisperse PST particles were obtained with two‐dimensionally tailored graft copolymers, with the number of grafted chains controlled and the polar component (HEMA) in the backbone chains balanced. As for the reactor, a stirred vessel with moderate agitation yielded uniform polymer particles, whereas sealed glass ampules with an overturning motion yielded broader size distributions. Increasing the polarity of the solvent in the continuous phase yielded smaller polymer particles with a gradual deterioration of monodispersity. Uniform polymer particles with a coefficient of variation of less than 6% were obtained up to 30 wt % solid contents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1788–1798, 2003 相似文献
14.
Jérôme Garnier Pierre-Emmanuel DufilsJérôme Vinas Yves VandervekenAlex van Herk Patrick Lacroix-Desmazes 《Polymer Degradation and Stability》2012,97(2):170-177
Poly(glycidyl methacrylate-co-butyl methacrylate)/poly(vinylidene chloride-co-methyl acrylate) (poly(GMA-co-BMA)/poly(VDC-co-MA)) composite latexes have been successfully synthesized via a two-stage emulsion polymerization process. In a first step, emulsion copolymerization of GMA and BMA was carried out in optimized conditions (low temperature, neutral pH, starved-feed conditions) to both limit the hydrolysis of epoxy groups and obtain small particle size (typically 30-50 nm size range). Composite latexes were then obtained by a second-stage seeded copolymerization of VDC and MA in the presence of tetrasodium pyrophosphate to control the pH and reach high molecular weight, leading to partial encapsulation of the seed particles (snow-man morphology, in agreement with theoretical expectations). Thermogravimetric analyses performed on the resulting composite particles showed that the epoxy-functionalized seed polymer behaved as an efficient thermal stabilizer of PVDC. 相似文献
15.
《先进技术聚合物》2018,29(3):1086-1093
Poly(eicosyl methacrylate‐co‐2‐hydroxyethyl methacrylate) is synthesized by free radical polymerization of eicosyl methacrylate and 2‐hydroxyethyl methacrylate by using 2,2′‐azobisisobutyronitrile as initiator in N,N‐dimethylformamide at 80°C. Copolymers of different molecular weights are synthesized and well characterized by different analytical techniques and used as a stabilizer in the preparation of polycaprolactone and polylactic acid particles by solvent evaporation method. The formation of the polymer particles and its morphology with respect to the stabilizer molecular weights, concentration, and reaction time are studied. Well dispersed poly(caprolactone) and poly(lactic acid) particles are formed, which demonstrated the efficiency of the copolymeric stabilizer. Polymer particle sizes and its stability depend on the molecular weights and concentration of the stabilizer. The surface morphology and particle sizes of the prepared particles are characterized by field emission scanning electron microscope. 相似文献
16.
Effects of the kind and concentration of stabilizers on the nonspherical shape of polystyrene (PS)/poly(methyl methacrylate) (PMMA) composite particles prepared by release of toluene from PS/PMMA/toluene droplets dispersed in stabilizer aqueous solution were examined. In the case of poly(vinyl alcohol), the surfaces of the obtained particles always had a single dimple. In the case of sodium dodecyl sulfate (SDS), the shapes of the composite particles changed from the dimple, via acorn, to spherical with increasing SDS concentration. It was clarified that the dimple and acorn shapes of the PS/PMMA composite particles were caused by contraction of the PS phase after hardening of the PMMA phase in excentered core-shell and hemisphere morphologies, respectively, which were formed by phase separation during toluene evaporation. 相似文献
17.
Ying Huang Xinlong Wang Xiaoxun Jin Tongwen Wang 《Journal of Thermal Analysis and Calorimetry》2014,117(2):755-763
Graphene oxide (GO) is used as a stabilizer in the Pickering emulsion polymerization of methyl methacrylate (MMA) to prepare PMMA/GO nanocomposites. Transmission electron microscope studies of the emulsion polymerization products showed that the average diameter of nanocomposite particles was about 150 nm, the transparent GO flakes covered the surface of the particles, and were well dispersed in polymer matrix. The influence of GO on the thermal stability of PMMA was investigated by thermogravimetry analysis and differential scanning calorimetry. The results showed that the thermal stability and the glass transition temperature (T g) of PMMA/GO nanocomposites were improved obviously compared with PMMA. The apparent activation energy (E a) for the degradation process of PMMA/GO nanocomposites was evaluated by Kissinger method, which indicated that their E a s were much higher than those of PMMA both in nitrogen and air atmosphere. 相似文献
18.
Cross-linked poly(methyl methacrylate) particles were prepared via dispersion polymerization in supercritical carbon dioxide
(scCO2) using poly(heptadecafluorodecyl methacrylate) (PHDFDMA) and 2,2′-azobisisobutyronitrile as the dispersant and the initiator,
respectively. The following chemicals were used as cross-linking agents: ethylene glycol dimethacrylate (EGDMA), 1,4-buthanediol
di(meth)acrylate (1,4-BD(M)A), and trimethylolpropane trimethacrylate. PHDFDMA was synthesized by solution polymerization
in scCO2. We investigated the effect of the chemical structure, concentration of the cross-linking agents, reaction pressure, and
CO2 density on the morphology, the polydispersity, and the cross-linking density of polymer particles. The resulting polymer
particle was characterized by field emission SEM, differential scanning calorimetry, and thermal gravimetric analysis. The
cross-linked PMMA particles is more agglomerate as the cross-linking agent concentration increased and as pressure decreased
at constant temperature. Glass-transition temperature (T
g) of the resulting polymer increased as the cross-linking agent increased with temperature and pressure increasing at the
same CO2 density. Decomposition temperature is slightly increased as 1,4-BDA concentration increased. From these results, we can confirm
that the thermal stability of the polymer increased as the cross-linking agent and EGDMA is the best cross-linking agent in
term of the thermal stability. 相似文献
19.
Kyung Min Do Haldorai Yuvaraj Min Hee Woo Hyun Gyu Kim Euh Duck Jeong Keith P. Johnston Kwon Taek Lim 《Colloid and polymer science》2008,286(11):1343-1348
A novel synthetic route to prepare polystyrene/SiO2 composite microparticles in supercritical carbon dioxide (scCO2) is presented. Silica particles with the size of 130 nm which were surface-modified with 3-(trimethoxysilyl) propyl methacrylate
were used as seeds in the dispersion polymerization of styrene in the presence of a polymeric stabilizer, poly(1,1-dihydroheptafluorobutyl
methacrylate-co-diisopropylaminoethyl methacrylate) to produce dry composite particles. The transmission electron microscopy analysis revealed
that the composite microspheres contained several silica particles. 相似文献
20.
Soleyman Hosseinzadeh Younes Saadat Samira Abdolbaghi Faramarz Afshar-Taromi Alireza Hosseinzadeh 《Colloid Journal》2014,76(1):104-112
In this work, seeded dispersion polymerization of styrene was carried out in the presence of various types of seed particles. We found that in the case of polystyrene and poly(methyl methacrylate) seeds, the shape of the resulting particles remained spherical. For styrene/poly(nbutyl methacrylate) (PnBMA) and styrene/poly(lauryl methacrylate) seeding particles, raspberry like particles were produced along with those of occluded morphology. We studied the effects of various polymerization factors such as concentrations of a stabilizer, an initiator, and a monomer, a weight ratio of methanol to water, a type of initiator, weight ratio of styrene to Pn-BMA seed particles, and polymerization temperature on the formation of these raspberry-like particles. The experimental results showed that the increase of concentrations of the initiator and the stabilizer as well as that of methanol favors the formation of such particles by increasing their surface roughness. An increase of the temperature of polymerization had the same effect on the morphology of resulting product. We hypothesized that the nucleation and growth of specifically fine-structured polystyrene domains on the surface of the Pn-BMA particles guides the formation of non-linear morphology during seeded polymerization in colloidal solution. 相似文献