Production of micron-sized, monodispersed, multilayered composite polymer particles by multistep seeded dispersion polymerization

 Micron-sized, monodispersed, poly(methyl methacrylate) (PMMA)/polystyrene (PS)/PMMA/PS multilayered composite particles were successfully produced by three-step seeded dispersion polymerizations in methanol/water media. The first seeded dispersion polymerization was carried out with 2-μm-sized, monodispersed PMMA particles.     

Production of micron-sized, monodisperse composite polymer particles having epoxy groups by seeded dispersion polymerization

 Micron-sized, monodisperse polystyrene (PS)/glycidyl methacrylate–divinylbenzene copolymer core/shell composite particles having epoxy groups in the shells were produced by seeded dispersion copolymerization of glycidyl methacrylate and divinylbenzene in an ethanol/water medium with 1.65-μm-sized, monodisperse PS seed particles. By chemical modifications of epoxy groups with sodium hydrogensulfite and dimethylamine, composite polymer particles having sulfonate and dimethylamino groups, respectively, in the shells were prepared. Received: 13 September 2000 Accepted: 31 January 2001     

Production of micron-sized monodispersed core/shell composite polymer particles by seeded dispersion polymerization

 The effect of the weight ratio of seed polymer/monomer on the morphology of the poly(methyl methacrylate) (PMMA)/polystyrene (PS) monodispersed composite particles produced by batch seeded dispersion polymerization of styrene with 1.64-μm-sized monodispersed PMMA seed particles in a methanol/water medium (4/1 w/w) was examined. In the PMMA/PS weight ratios of 3/1 and 2/1, the composite particles had a clear morphology consisting of a PMMA core and a PS shell. In the ratio of 1/1, a lot of small PS domains were observed in the PMMA core though the PS shell was still formed. By stepwise addition of styrene monomer, the formation of the small PS domain was depressed and complete core/shell morphology was formed. Absorption/release treatments of toluene into/from the PMMA/PS (1/1 w/w) composite particles resulted in a drastic morphological change from the core/shell structure to a multi- layered one. Received: 2 February 1999 Accepted in revised form: 7 April     

Encapsulation of inorganic particles by dispersion polymerization through ultrasonic irradiation

1 Introduction In recent literature, several processes have been de-scribed to synthesize particles that consist of an inor-ganic core surrounded by a polymer shell. The tech-nique of polymer encapsulation is becoming more and more popular since polymer-e…     

Production of hollow polymer particles by suspension polymerization

 Polymer particles having single hollow in the inside were successfully prepared by suspension polymerization for divinylbenzene/ toluene droplets dissolving polystyrene (PS) in an aqueous solution of poly(vinyl alcohol). Such a hollow polymer particle was not obtained without PS. The hollow structure was affected by the molecular weight and the concentration of PS. Received: 3 December 1997 Accepted: 27 March 1998     

Production of micron-sized monodispersed core/shell polymethyl methacrylate/polystyrene particles by seeded dispersion polymerization

 Micron-sized monodispersed polymethyl methacrylate (PMMA)/polystyrene (PS) (PMMA/PS=2/1, wt ratio) composite particles consisting of PMMA-core and PS-shell were successfully produced by seeded dispersion polymerization of styrene in a methanol/water medium in the presence of about 2 μm-sized monodispersed PMMA particles. From the view point of thermodynamic equilibrium, such a morphology is difficult to form by usual seeded polymerization in a polar medium such as water. It is concluded that seeded dispersion polymerization in which almost all monomers and initiators exist in the medium has an advantage to produce core/shell polymer particles in which polymer layers accumulate in their order of the production regardless of the hydrophobicity of polymers, because of high viscosity in polymerizing particles. Received: 9 December 1996 Accepted: 26 February 1997     

Influence of particle diameter on the morphology of micron-sized, monodispersed composite polymer particles produced by seeded polymerization for the dispersion of highly monomer-swollen polymer particles

 Micron-sized, monodispersed polystyrene (PS)/poly (n-butyl methacrylate) (PBMA) composite particles, in which the PS domain(s) were dispersed in a PBMA continuous phase, were produced by seeded polymerization for dispersions of n-butyl methacrylate (BMA) swollen PS particles in a wide range of PS/BMA ratios in the presence of NaNO₂ as a water-soluble inhibitor. Moreover, in order to change the diameter of the composite particles at same PS/BMA ratio, PS/PBMA (1/150 w/w) composite particles were produced using five kinds of PS particles in a range of diameters from 0.64 to 3.27 μm as seeds. The percentages of the PS/PBMA composite particles having double and triple and over PS domains, which were thermodynamically unstable morphologies, increased with the increase in the diameter of BMA swollen PS particles. There was a clear influence of the size of the swollen particles on the morphology of the PS/PBMA composite particles produced. Received: 30 September 1999/Accepted: 18 April 2000     

Synthesis, polymerization, and dispersion copolymerization of poly(ethylene oxide) macromonomers carrying methacryloyloxyalkyl end groups

 Poly(ethylene oxide) macromonomers carrying methoxy group on the one (α-) end and methacryloyloxyhexyl or methacryloyloxydecyl group on the other (ω-) end were prepared, homopolymerized in water, and dispersion-copolymer-ized with styrene or methyl methacrylate in a methanol–water mixture. They were found to polymerize more rapidly and to produce stable polystyrene dispersions more effectively, as compared to the corresponding macromonomers carrying either α-methoxy and or α-dodecyloxy and ω-methacryloyloxy end groups. Thus, the amphiphilic constitution of the macromonomers such that favors the polymerizing methacrylate end groups to locally concentrate into the micelle core or to the particle surface while the poly(ethylene oxide) chains extending to the medium appears to be most important in enhancing their polymerizability and effectiveness as reactive steric stabilizers. On the other hand, stable poly(methyl methacry-late) particles with a number of craters or pleats on the surface were produced with a PEO macromono-mer with α-methoxy and ω-methacryl-oyloxy end groups. Received: 4 September 1996 Accepted: 18 October 1996     

Morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization for the dispersion of highly monomer-swollen polymer particles

 Monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles having 9.4 μm in diameter were produced by seeded polymerization for the dispersion of highly n-butyl methacrylate (BMA)-swollen PS particles, and their morphologies were examined. The highly BMA-swollen PS particles (about 150 times the weight of the PS seed particles) were prepared by mixing monodispersed 1.8 μm-sized PS seed particles and 0.7 μm sized BMA droplets prepared with an ultrasonic homogenizer in ethanol/water (1/2, w/w) medium at room temperature. After NaNO₂ aqueous solution as inhibitor was added in the dispersion, the seeded polymerization was carried out at 70 °C. In an optical microscopic observation, one or two spherical high contrast regions which consisted mainly of PS were observed inside PS/PBMA composite particles. In the PS domain, there were many fine spherical PBMA domains. Such morphologies were based on the phase separation of PS and PBMA within the homogeneous swollen particles during the seeded polymerization. Received: 04 June 1997 Accepted: 27 August 1997     

Synthesis of functional polymer particles by dispersion polymerization in organic media: A tool toward stable electrophoretic inks

In this article, a simple route to obtain particles in one step from functional ionizable monomers in organic media by the use of acrylate‐based macroinitiator synthesized by nitroxide‐mediated radical polymerization is presented. Different positively ionizable monomers like 4‐vinylpyridine, (dimethylamino)ethyl methacrylate, or negatively ionizable ones like methacrylic acid and acrylic acid were tested. Several parameters were studied to control the particles size, their stability in different organic media, and the possibility to crosslink them. Finally, well‐defined, depending of conditions, functional latexes in organic media were produced in a simple way. This synthetic process constitutes the first step to produce electrophoretic inks for display applications such as electronic paper. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4608–4617     

Morphological investigations of crosslinked polystyrene microspheres by seeded polymerization

 Crosslinked polystyrene microspheres with novel surface and inner morphologies were synthesized by seeded polymerization following a seed-swelling method, using uncrosslinked polystyrene microspheres as seeds and a mixture of toluene, styrene (St), and divinylbenzene (DVB) as the swelling agent. With the increasing toluene/ (St+DVB) ratio, the crosslinked particles changed from smooth-surfaced spheres to deformed spheres with dimples or heavy dents at the surface. A single hole inside the spherical particles was produced at low St/DVB ratio, while higher St/DVB ratios gave irregular dented or dimpled particles. Ultrathin cross-section observation by TEM revealed a non-uniformly crosslinked inner structure. Received: 20 January 1998 Accepted: 14 April 1998     

Morphology of anomalous polystyrene/ polybutyl acrylate composite particles produced by seeded emulsion polymerization

 Recently, we found that “golf ball”-like polystyrene (PS)/polybutyl acrylate (PBA) composite particles could be produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles. In this article, the effects of the polymerization temperature, BA monomer concentration, and the presence of 1-octanol, which is a good solvent for PBA and a poor solvent for PS in the polymerization, on the morphology was studied. Received: 25 February 1997 Accepted: 4 October 1997     

Micron-sized monodispersed polymer particles produced by seeded polymerization for the dispersion of high swelling of polymer particles with a large amount of monomer

 Micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) composite particles were produced as follows. First, 1.77 μm-sized monodispersed PS seed particles produced by dispersion polymerization were dispersed in ethanol/water (1/2, w/w) medium dissolving poly(vinyl alcohol) as a stabilizer. n-Butyl methacrylate (BMA) monomer dissolving benzoyl peroxide initiator was emulsified in ethanol/water (1/2, w/w) solution of sodium dodecyl sulfate as emulsifier with ultrasonic homogenizer, and the BMA monomer emulsion was mixed with the PS seed emulsion. The PS seed particles absorbed with a large amount of BMA (about 150 times weight of the seed particles) for 2 h to about 10 μm in diameter while keeping good monodispersity and BMA droplets disappeared finally. The seeded polymerization was carried out at 70 °C after a certain amount of water was added to depress the redissolving of BMA from the swollen particles into the medium by raising from room temperature to the polymerzation temperature. Received: 21 February 1996 Accepted: 4 September 1996     

Synthesis and characterization of oxazoline-functional polymer particles by free radical nonaqueous dispersion polymerization

A novel oxazoline-functional methacrylate was prepared and employed as comonomer to produce nonaqueous dispersions of oxazoline-functional polymer particles. In nonaqueous free radical dispersion copolymerization of methylmethacrylate in the presence of oxazoline-functional methacrylate, ethyleneglycoldimethacrylate crosslinking agent, AIBN initiator, and polystyrene-block-poly(ethene-alt-propene) dispersing agent, the average polymer particle size, varying between 100 and 500 nm, was controlled by the dispersing agent contents. According to titration with HClO₄ all oxazoline groups regardless of their location at particle surface or bulk, were accessible. Glass transition temperature decreased from 120 to 0°C when oxazoline functional methacrylate was increased from 0 to 95 mol %. As imaged by atomic force microscopy incorporation of the new oxazoline-functional methacrylate improved film formation. Oxazoline-functional polymer particles were easy to redisperse in a variety of other diluents. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2539–2548, 1997     

Preparation of polystyrene/poly (4-butyltriphenylamine) composite particles by chemical oxidative seeded dispersion polymerization

Polystyrene (PSt)/poly (4-butyltriphenylamine; PBTPA) composite particles was prepared by a chemical oxidative seeded dispersion polymerization of (4-butyltriphenylamine) with PSt seed particles that were prepared by nonaqueous dispersion polymerization of styrene. Monodisperse composite particles were obtained when the ratio of monomer to seed, the rate of monomer feed, and poly(N-vinyl pyrrolidone; PVP) concentration was appropriately selected. The introduction of PBTPA was confirmed by the presence of the characteristic absorption band attributed to PBTPA from a Fourier transform infrared spectra. The solvent extraction with ethyl acetate revealed that composite particles consisted of PSt core and PBTPA shell. Then two-dimensional arrays of composite particles were also fabricated.     

The morphology of composite polymer particles produced by multistage soapless seeded emulsion polymerization

 Composite polymer particles which contain poly(methyl methacrylate) (PMMA) and polystyrene (PS) components (PMMA/PS composite particle) were synthesized by the method of multistage soapless seeded emulsion polymerization. In this study, the process of multistage soapless seeded emulsion polymerization included two-stage polymerization, three-stage polymerization or four-stage polymerization. The morphologies of the PMMA/PS composite particles were studied. The kinetic factor was the main force to control the morphology of the linear PMMA–PS composite particles which were synthesized by the method of two-stage reaction. Both the kinetic factor and the thermodynamic factor decide the morphology of the linear composite particles which were synthesized by the method of either three-stage or four-stage reaction. However, the thermodynamic factor cannot influence the morphology of the PMMA/PS composite particles with a cross-linked structure which were synthesized by the method of three-stage reaction. The cross-linked composite polymer particles had the morphology of a multilayer structure, which showed that the polymer layers accumulated in their order of production. Received: 9 January 2001 Accepted: 14 June 2001     

Preparation of poly(4-butyltriphenylamine) particles by chemical oxidative dispersion polymerization

Photoconductive poly(4-butyltriphenylamine) particles were prepared by a chemical oxidative dispersion polymerization. The utilization of statistical copolymer of methyl methacrylate with 2-hydroxyethyl methacrylate (30:70) as a dispersant afforded particles with the narrowest distribution when the other experimental conditions such as the rate of monomer feed, and the dispersant concentration were appropriately selected. Porous particles were obtained at 40 °C using poly(vinyl pyrrolidone) as a dispersant.     

Mechanism of dispersion polymerization of L-lactide initiated with 2,2-dibutyl-2-stanna-1,3-dioxepane

 Biodegradable polyester microspheres were synthesized directly by ring-opening polymerization of l-lactide initiated with 2,2-dibutyl-2-stanna-1,3-dioxepane. The polymerizations were carried out at 95 °C in a mixture of organic solvents (heptane/1,4–dioxane 4:1 v:v), in the presence of poly(dodecyl acrylate)-g-poly(ɛ-caprolactone) used as a surface-active agent. Under these conditions the poly(L-lactide) synthesized was shaped into microspheres. The absence of new particles in the polymerizations with multistep monomer addition indicated that after the formation of particle seeds the propagation proceeds exclusively inside the microspheres. The mean volume of these microspheres was proportional to the monomer conversion. It was found that regardless of the initiator concentration the average number of poly(L-lactide) macromolecules in one microsphere was 1.84 × 10⁸. Matrix-assisted laser desorption ionization time of flight spectroscopy of poly(L-lactide) in the microspheres indicated that the propagation in the particles was accompanied by intra- and intermolecular transesterification side reactions, resulting in reshuffling of the polymer segments and the formation of cyclic oligomers. Received: 20 December 2000 Accepted: 7 June 2001     

Kinetics of chemical oxidative dispersion polymerization of 3,5‐xylidine in aqueous medium using a PH stat method

Kinetics of chemical oxidative dispersion polymerization of 3,5‐xylidine (Xy) in aqueous medium with ammonium persulfate (APS) as an oxidant was studied by monitoring the amount of proton released from Xy monomer, which was obtained from the amount of potassium hydroxide (KOH) solution added to keep constant pH values using a pH stat. The initial polymerization rate (R) [mol/L/min] of Xy was expressed as follows: R = 1.65 (1 − α) [Xy] [APS], where α is the degree of ionization of Xy, and [Xy] and [APS] are concentrations of Xy and APS, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4238–4246, 2000     

Synthesis of polybutadiene‐based particles via dispersion ring‐opening metathesis polymerization

Latex particles based on 1,4‐polybutadiene were synthesized via dispersion ring‐opening metathesis copolymerization of 1,5‐cyclooctadiene with a α‐norbornenyl poly(ethylene oxide) macromonomer. Stable but polydisperse colloidal dispersions in the 50 nm to 10 μm size range were obtained. In this work, particular attention was paid to the effects of the kinetics of copolymerization on the structure of the graft copolymers formed and on the onset of turbidity. Strategies to prepare monodisperse polybutadiene particles were also designed through the growth of a polybutadiene shell from a well‐defined polynorbornene seed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1154–1163, 2004