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     

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     

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 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.     

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     

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     

Tailoring of carboxyl‐decorated magnetic latex particles using seeded emulsion polymerization

In this research, submicron and carboxyl‐functionalized magnetic latex particles were elaborated by using seeded emulsion polymerization technique in presence of oil‐in‐water (o/w) magnetic emulsion as seed. The polymerization conditions were optimized in order to get well‐defined latex particles with magnetic core and polymer shell bearing carboxylic (–COOH) functionality. Starting from (o/w) magnetic emulsion as seed, synthesis process was performed by copolymerization of styrene (St) monomer with the cross‐linker divinylbenzene (DVB) in presence of 4,4′‐azobis(4‐cyanopentanoic acid) (ACPA) as a carboxyl‐bearing initiator. The prepared magnetic latex particles were first characterized in terms of particle size, chemical composition, morphology, magnetic properties, magnetic content, and colloidal stability using various techniques, e.g. particle size analyzer using dynamic light scattering (DLS) technique, Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, and zeta potential measurements as a function of pH of the dispersion media, respectively. The prepared magnetic latex particles were then used as second seed for further functionalization with methacrylic acid (MAA) in order to enhance carboxylic groups on the magnetic particle's surface. The results showed that final magnetic latex particles possessed spherical morphology with core‐shell structure and enriched carboxylic acid functionality. More importantly, they exhibited superparamagnetism with high magnetic content (58.42 wt%) and high colloidal stability, which considered as the main requirements for their application in the biomedical diagnostic domains. Copyright © 2017 John Wiley & Sons, Ltd.     

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     

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     

Synthesis of ZnO/polystyrene composites particles by Pickering emulsion polymerization

ZnO/polystyrene composite particles were synthesized by Pickering emulsion polymerization. ZnO nanoparticles were first prepared by reaction of zinc acetate and sodium hydroxide in ethanol medium. Then different amount of styrene monomer was emulsified in water in the presence of ZnO nanoparticles either by mechanical stirring or by sonication, followed by polymerization of styrene. Two kinds of initiators were used to start the polymerization, azobisisobutyronitrile (AIBN) and potassium persulfate (KPS). The X-ray diffraction pattern verified the crystal structure of ZnO and FT-IR spectra evidenced the existence of ZnO and polystyrene (PS) in ZnO/polystyrene composite particles. Different morphologies were observed for the composite particles when using different initiators. From TEM photographs, AIBN-initiated system produced mainly core-shell composite particles with PS as core and ZnO as shell, while KPS-initiated system showed both composite particles and pure PS particles. Two schemes of reaction mechanism were proposed to explain the morphologies accordingly. Both systems of composite particles showed good pH adjusting ability.     

Effects of surfactants on the morphology of composite polymer particles produced by two‐stage seeded emulsion polymerization

Poly(methyl methacrylate) (PMMA)–polystyrene (PS) composite polymer particles were synthesized in the presence of a surfactant by two‐stage seeded emulsion polymerization. The first stage was the synthesis of PMMA particles by soapless emulsion polymerization; the second stage was the synthesis of the PMMA–PS composite polymer particles with the PMMA particles as seeds. In the second stage of the reaction, three kinds of surfactants—sodium laurate sulfate (SLS), polyoxyethylene (POE) sorbitan monolaurate (Tween 20), and sorbitan monolaurate (Span 20)—were used to synthesize the PMMA–PS composite particles. Both the properties and concentrations of the surfactants influenced the morphology of the composite particles significantly. Core–shell composite particles, with PS as the shell and PMMA as the core, were synthesized in the presence of a low concentration of the hydrophilic surfactant SLS. This result was the same as that in the absence of the surfactant. However, a low concentration of Tween 20 led to composite particles with a core/strawberry‐like shell morphology; the core region was a PS phase, and the strawberry‐like shell was a PS phase dispersed in a PMMA phase. With an increase in the concentration of SLS, the morphology of the composite particles changed from core (PMMA)–shell (PS) to core (PS)–shell (PMMA). Moreover, the effects of a high concentration of Tween 20 or Span 20 on the morphology of the PMMA–PS composite particles were investigated in this study. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2224–2236, 2005     

Production of micron-sized monodispersed composite polymer particles by seeded polymerization utilizing the dynamic swelling method

 In order to develop the seeded polymerization technique utilizing the dynamic swelling method (DSM) proposed by authors for the production of micron-sized mono-dispersed “composite” polymer particles consisting of two kinds of polymers, the seeded polymerization for the dispersion of ethyl methacry-late (EMA)-swollen PS particles prepared utilizing DSM was carried out. Monodispersed PS/poly(ethyl methacrylate) (PEMA) composite particles having 7 μm in diameter were produced by the addition of NaCl to lower the solubility of EMA in medium and by the addition of CuCl₂ as a water-soluble inhibitor to depress the by-production of submicron-sized PEMA particles. Received: 16 July 1996 Accepted: 10 October 1996     

Synthesis of submicron-sized peanut-shaped poly(methyl methacrylate)/polystyrene particles by seeded soap-free emulsion polymerization

Submicron-sized peanut-shaped poly(methyl methacrylate)/polystyrene(PMMA/PS) particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles.The obtained peanut-shaped particles showed a novel internal morphology:PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.     

Influences of the locations of monomer and initiator in the seeded polymerization systems on the morphologies of micron-sized monodispersed composite polymer particles

Three kinds of micron-sized monodispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/BMA=2/1, wt. ratio) were produced by two kinds of seeded polymerizations ofn-butyl methacrylate (BMA) in the presence of about 2 m-sized monodispersed PS particles, and their morphologies were examined. One was produced by a seeded dispersion polymerization where almost monomers and initiators exist in an ethanol/water (1/1, w/w) medium. The others two were produced by seeded polymerizations utilizing the dynamic swelling method, where almost monomers exist in the PS seed particles, with 2,2-azobisisobutyronitrile initiator in the monomer-swollen particles and with 2,2-azobis [2-(2-imidazolin-2-yl)propane] initiator in an ethanol/water (1/5, w/w) medium. In the former polymerization, the produced composite particles had a core-shell structure consisting of a PS-core and a PBMA-shell, whereas in the latter two polymerizations, they had a POO (Polymeric Oil-in-Oil) structure consisting of a PS-matrix and many PBMA-domains, regardless of the location of initiator in the systems. From these results, it is concluded that the location of BMA monomer in the seeded polymerization systems with micron-sized monodispersed PS seed particles greatly affects the morphologies of produced PS/PBMA composite particles.Part CLI of the series Studies on Suspension and Emulsion     

Influence of the swelling state of seed polymer particles with monomer on the morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization utilizing the dynamic swelling method

 Micron-sized mono-dispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/PBMA=2/1 by weight) having a heterogeneous structure in which many fine PBMA domains dispersed in a PS matrix near the particle surface were produced by seeded polymerization of n-butyl methacrylate (BMA) of which almost all had been absorbed by 1.8 μm-sized monodispersed PS seed particles utilizing the dynamic swelling method. The morphology was varied by changing the PS/BMA ratio and polymerization temperature. It was concluded that the swelling state of 2 μm-sized BMA-swollen PS particles in the seeded polymerization process is one of the important factors to control the morphology of the composite particles. Received: 27 November 1996 Accepted: 21 March 1997     

Production of electrically conductive, core/shell polystyrene/polyaniline composite particles by chemical oxidative seeded dispersion polymerization

Micron-sized, monodispersed, electrically conductive polystyrene (PS)/polyaniline (PAn) composite particles were produced by chemical oxidative seeded dispersion polymerization of aniline at 0 °C with 1.37-μm-sized, monodispersed PS seed particles in HCl aqueous solution, where the pH value was kept at 2.5 with a pH stat. The composite particles consisted of a PS core and a PAn shell. A pellet of the composite particles had a conductivity of 3.4 × 10⁻³ S/cm. Received: 5 April 2000 Accepted: 10 August 2000     

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     

Production of core/shell polystyrene/poly(3,5-xylidine) composite particles by chemical oxidative seeded dispersion polymerization

Micron-sized monodispersed polystyrene (PS)/poly(3,5-xylidine) (PXy) composite particles were produced by chemical oxidative seeded dispersion polymerization of 3,5-xylidine at 20 °C with 1.6-μm-sized monodispersed PS seed particles in HCl aqueous solution, the pH of which was always kept at 2.5 with a pH stat. The composite particles produced consisted of a PS core and a PXy shell. Received: 16 December 1998 Accepted in revised form: 25 March 1999     

Production of micron-sized, monodispersed, multihollow polystyrene/poly(3,5-xylidine) composite particles by chemical oxidative seeded polymerization

 Micron-sized, monodispersed polystyrene/poly(3,5-xylidine) composite polymer particles were produced by chemical oxidative seeded polymerization of 3,5-xylidine with 1.37-μm-sized, monodispersed polystyrene seed particles. The chemical oxidative seeded polymerization was conducted in an aqueous medium at 25 °C in the presence of poly(vinyl alcohol) as a stabilizer using ammonium persulfate as an oxidant. The composite particles had a multihollow structure. Received: 30 June 1999/Accepted in revised form: 21 October 1999