Dispersion Polymerization Of Styrene Research Articles

Preparation of Ag/PS composite particles by dispersion polymerization under ultrasonic irradiation

In this paper, the Ag/PS composite particles were prepared and characterized according to the following steps. First, the nano-silver particles were pretreated with the surfactants under ultrasonic irradiation. Second, the dispersion polymerization of styrene in a water–ethanol (1/6 wt/wt) medium, with poly(N-vinyl pyrrolidone) (PVP) as stabilizer and 2,2′-azobisizobutyronitrile (AIBN) as initiator in the presence of nano-silver particles was initiated with N2 purging through ultrasonic irradiation by taking its advantages of the combined effects of dispersion, crushing, activation, and initiation. Finally, the polymerization dynamics characteristic was studied, and the encapsulation of composite particles were investigated by SEM, FTIR, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and X-ray diffraction patterns (XRD).

The effect of camphorsulfonic acid in TEMPO-mediated bulk and dispersion polymerization of styrene

The TEMPO-mediated living free-radical bulk and dispersion polymerization of styrene in the presence of camphorsulfonic acid (CSA) are investigated. In the absence of TEMPO and CSA in the bulk polymerization, a conversion of 93% is achieved within 6 hr of polymerization. When only TEMPO is involved in this polymerization, the pseudo-living free-radical polymerization is well achieved, however, the polymerization rate becomes quite slow. This retardation of the polymerization rate is solved by the addition of a low concentration of CSA. In the TEMPO-mediated dispersion polymerization in the presence of CSA, similar trends in the conversion, kinetics, and PDI are observed as those observed in the case of bulk polymerization. When only TEMPO is used in the dispersion polymerization, the resulting particle size becomes quite broad, due to the prolonged polymerization time. However, when a 1.0 molar ratio of CSA to TEMPO is added to the TEMPO-mediated dispersion polymerization, fairly monodisperse PS microspheres having an average size of 5.83 μm and a CV of 3.4% are successfully obtained, due to the narrow molecular weight distribution of the intermediate oligomers and shortening of the polymerization time. This result indicates that the addition of CSA to the TEMPO-mediated bulk and the use of dispersion polymerization not only shortens the polymerization time, but also greatly improves the uniformity of the microspheres.

Synthesis and Characterization of Polyurethane-Derived Telechelic Macromonomer Cross-Linkable Stabilizer (TMCS)

The telechelic macromonomer cross-linkable stabilizer (TMCS) was synthesized by the reaction of isocyanate-terminated prepolymer with methacrylamide and was successfully employed as a steric stabilizer and possible cross-linking agent in the dispersion polymerization of styrene. The urethane and methyl groups in TMCS are found in the spectrum of PS microspheres, and the reactive double bonds in TMCS disappear after polymerization with styrene. The qualitative analysis reveals that the symmetric molecular structure with vinyl group in TMCS takes part in the reaction with styrene, and it is proposed that the PS microspheres are substantially cross-linked. In reality, for the 100 wt % TMCS system, the PS is not totally soluble in THF, remaining as a translucent fully-swollen gel in THF. Thus, these qualitative structural investigations suggest that the TMCS serves as a reactive stabilizer as well as a cross-linking agent.

Covalent immobilization of human serum albumin onto reactive polypyrrole-coated polystyrene latex particles

Polypyrrole-coated polystyrene latex particles bearing reactive N-succinimidyl functional groups (PS-PPyNSE) were prepared by the in-situ copolymerization of pyrrole (Py) and the active ester-functionalized pyrrole (PyNSE) in the presence of 1 µm diameter-sized polystyrene (PS) latex particles. These particles were prepared by dispersion polymerization of styrene using poly(N-vinylpyrrolidone), PNVP, as a steric stabilizer. The initial comonomer fractions (in mol%) were 25/75, 50/50 and 75/25 for pyrrole and pyrrole-NSE, respectively. The functionalized polypyrrole-coated PS particles (PS-PPyNSE) were characterized in terms of their particle size and surface morphology using transmission electron microscopy (TEM). Infrared and X-ray photoelectron spectroscopy (XPS) detected pyrrole-NSE repeat units at the surface of the latex particles, indicating that this monomer had indeed copolymerized with pyrrole. Furthermore, the core–shell structure of the PS-PPyNSE particles was confirmed by etching the polystyrene core in THF, leading to the formation of hollow conducting polymer capsules. Reactivity of the PS-PPyNSE75 particles was investigated using 2-aminoethanol and 2-mercaptoethanol, two model molecules bearing functional groups borne by proteins. Incubation of the particles with these model molecules clearly showed that the particles are reactive towards amine and thiol groups leading to the formation of interfacial amide and thioester bonds, respectively. The PS-PPyNSE particles were further evaluated as bioadsorbents of human serum albumin (HSA) used as a test protein. It was shown that the HSA macromolecules were immobilized at the surface of PS-PPyNSE particles by forming interfacial amide groups. Incubation of the HSA-grafted latex particles with anti-HSA resulted in immediate flocculation. This indicates that, despite probable conformational changes resulting from contact with NSE-functionalized latexes, HSA proteins retain their biological activity when immobilized on the particle surface. These PS-PPyNSE particles are therefore alternative candidates for visual diagnostic assays.

Encapsulation of inorganic particles by dispersion polymerization through ultrasonic irradiation

The nano-silica/polystyrene composite particles were prepared and characterized according to the following steps. First, the nano-silica particles were pretreated with surfactants under ultrasonic field. Second, the dispersion polymerization of styrene in a water/ethanol (1/6, weight ratio) medium, with poly(N-vinyl pyrrolidone) (PVP) as stabilizer and 2,2′-azobisizobutyronitrile (AIBN) as initiator in the presence of nano-silica particles was initiated with N 2 purging through ultrasonic irradiation by taking its advantages of multieffect, i.e. dispersion, crushing, activation, and initiation. Finally, the polymerization kinetics characteristics were studied, and the encapsulation of composite particles was investigated with optical microscope, SEM, TEM, FTIR, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

New micrometer-sized monodispersed self-assembled amphiphilic polystyrene/poly( n-butyl methacrylate) composite particles of hemispherical morphology: synthesis and characterization

Uniform micron-sized polystyrene template particles surface grafted with polyvinylpyrrolidone were prepared by dispersion polymerization of styrene in alcoholic solvents in the presence of polyvinylpyrrolidone as stabilizer. Poly(acrylic acid, sodium salt) derivatized polystyrene/ poly( n-butyl methacrylate) micron-sized composite particles of hemispherical morphology and narrow size distribution were formed by a single-step swelling of the uniform polystyrene template microspheres dispersed in water with emulsion droplets of the monomer n-butyl methacrylate containing the initiator benzoyl peroxide. n-Butyl methacrylate was then polymerized at 73 °C within the template microspheres in the presence of the water-soluble monomer acrylic acid, sodium salt. The sodium ions of the poly(acrylic acid) derivatized composite particles were then replaced with dodecylammonium ions by interacting these composite particles with excess dodecylamine hydrochloride. As a result of this process the surface of the hemispherical composite particles composed of hydrophilic polyvinylpyrrolidone chains on the polystyrene phase and hydrophobic dodecyl groups on the poly(acrylic acid) derivatized poly( n-butyl methacrylate) phase. These newly formed micron-sized composite particles show amphiphilic characteristics and aggregate to form micelle-like spherical clusters. The ability to control the template polystyrene microspheres’ dimensions and various polymerization parameters may open a wide variety of self-assembled spherical and other structures composed of micron-sized particles for various fundamental and practical applications such as self-assembly processes and the formation of photonic bandgap crystals.

Emulsion and dispersion polymerization of styrene in the presence of PEO macromonomers with p-vinylphenylalkyl end groups

Poly(ethylene oxide) (PEO) macromonomers with α- p-vinylphenylalkyl (propyl, pentyl, and hexyl) and ω-hydroxy end groups were applied to emulsion and dispersion polymerization of styrene as reactive emulsifiers and dispersants in water and in methanol-water mixture (9:1 v/v), respectively. Nearly monodisperse microspheres of submicron to micron size were obtained. Particle size in the emulsion system was one or half order of magnitude smaller than that in the dispersion system, while in both systems the size decreased approximately according to minus one half power of the macromonomer concentration in weight. The particle size was substantially independent on the PEO chain length and also on the spacer alkyl chain length of the α-polymerizing end group. The total weight of the PEO chains incorporated by copolymerization into the particle surfaces (shells), relative to that of styrene polymerized into the particle cores, appears to be a key factor for controlling the particle size. To cite this article: K. Landfester et al., C. R. Chimie 6 (2003).

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

AbstractThe 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

Affinity chromatography of DNA on nonporous copolymerized particles of styrene and glycidyl methacrylate with immobilized polynucleotide

Nonporous particles of microsize were prepared by the dispersion polymerization of styrene and glycidyl methacrylate and chemically modified to introduce amino groups on the surface by grafting with either hexamethylenediamine or N-methyl-1,3-propanediamine. Aminated particles were then coupled with phosphorylated single-stranded polynucleotides at the 5 ′-end through covalent linkages. The affinity columns packed with these prepared polynucleotide-immobilized particles effectively retained single-stranded DNA, which could base-pair with the immobilized sequence. Bound DNAs could be eluted to yield a sharp peak by using an aqueous solution of 0.4 M NaOH. The nonspecific adsorption due to the electrostatic interaction between the polynucleotide and the residual amino groups on the particle surface via the amination with hexamethylenediamine was significant and could only be reduced by using a high salt (NaCl) concentration. A higher salt concentration in the elution solution could result in a portion of complementary polynucleotide eluted in the nonretained fraction. However, the nonspecific adsorption of polynucleotides was insignificant in the column packed with DNA-immobilized particles prepared via amination using N-methyl-1,3-propanediamine. The column was effective for microanalysis of sequence-specific DNA.

Dispersion polymerization of n‐butyl acrylate

AbstractThe dispersion polymerization of n‐butyl acrylate (BA) was investigated using alcohol/water mixtures as the dispersion medium, 4,4′ ‐azobis‐(4‐cyanopentanoic acid) as the initiator, and polyvinylpyrrolidone (PVP) as the stabilizer. The effects of polymerization parameters, such as the alcohol/water ratio in the medium and the type and concentration of the polymeric stabilizer, on the resulting particle size and size distribution were studied. The final particle size and the stability of the dispersion system were found to be greatly influenced by the type of alcohol used in the mixture; that is, methanol or ethanol, even though the apparent solubility parameters are almost the same for the two types of mixtures. Poly(butyl acrylate) particles with controlled size and size distribution (monodisperse), and gel content were successfully prepared in a 90/10 methanol/water medium. It was found that the particle size decreased with increasing initiator concentration. This is the opposite of what was previously reported in the dispersion polymerizations of styrene and methyl methacrylate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2692–2709, 2002

Synthesis and characterization of micrometer‐sized particles of narrow size distribution with chloromethyl functionality on the basis of single‐step swelling of uniform polystyrene template microspheres

AbstractPolystyrene template microspheres of 1.4 ± 0.1 μm were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2‐methoxy ethanol. These template particles were then swelled at room temperature in a single step with emulsion that was prepared in sodium dodecyl sulfate aqueous solution from a swelling solvent (dibutyl phthalate) containing the initiator (benzoyl peroxide) and monomer(s) (chlormethylstyrene, divinylbenzene, or ethylene dimethacrylate). Composite uniform particles composed of the template polystyrene and noncrosslinked or crosslinked polychloromethylstyrene were prepared by polymerizing the monomer(s) within the swelled particles at 73 °C. Crosslinked uniform polychloromethylstyrene particles of higher surface area were formed by dissolving the template polystyrene polymer of the composite particles. The influence of various reaction parameters, such as dibuthyl phthalate concentration, chloromethylstyrene concentration, crosslinker type and concentration, and so forth on the molecular weight, size, size distribution, shape, morphology, surface area, and decomposition temperature of the particles was investigated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1342–1352, 2002

The dispersion polymerization of unsaturated monomers initiated by the macromonomeric initiator

The dispersion polymerizations of styrene (St) and methyl methacrylate (MMA) initiated by poly(oxyethylene) macroinimer (PEO-MIM) in ethanol/water were investigated at 50, 60 and 80 °C. The polymerisation rate vs. conversion dependence was described by with a maxim at the beginning of polymerisation. Polymerization was faster with MMA than with St. The limiting conversion was inversely proportional to temperature and was much more pronounced with St. The rate of polymerization increased with temperature. The overall initial activation energy increased with conversion and reached value ca. 25 kJ.mol -1 for MMA and 50 kJ.mol -1 for styrene at ca. 60% conversion. The particle size was observed to decrease with increasing the macroinimer concentration. The polymer dispersions were unstable and a large amount of coagulum appeared during the polymerisation especially in the styrene-containing reaction system.

Dispersion Polymerization of Styrene in Ethanol−Water Mixture Using Polystyrene-b-poly(ethylene oxide) Macromonomers as Stabilizers

The dispersion polymerization of styrene in an ethanol−water mixture using polystyrene-b-poly(ethylene oxide) macromonomers as stabilizers has been investigated. The influence of parameters such as the nature of the polymerizable group, the hydrophilic/hydrophobic balance, the overall molar mass, and the molecular architecture of the macromonomers on the colloidal dispersion has indeed been studied. Macromonomers of rather low molar mass and exhibiting high critical micellar concentration were best suited to produce stable particles. Latex particles of rather narrow size distribution could be obtained in the range of 300−350 nm with styrenyl or maleate ended PS-b-PEO macromonomers.

Carboxyl carrying-large uniform latex particles

Uniform polystyrene particles in the size range of 1.9–6.2 μm were used as the seeds in a multistep polymerization, to produce compact or macroporous particles in the size range of 3–13 μm with reasonably narrow size distributions (i.e. CV<5%). The seed particles with different sizes and molecular weights could be achieved by the dispersion polymerization of styrene. In the synthesis of carboxyl carrying-particles, the seed latices were first swollen by a low molecular weight-organic agent (i.e., dibutylphthalate, DBP), then by styrene (S)–methacrylic acid (MAA)–divinylbenzene (DVB) mixture including an oil-soluble initiator (i.e. benzoyl peroxide, BPO). The final particles were obtained by the polymerization of monomer mixture in the swollen seed particles by keeping the particle uniformity. The average size, size distribution, surface morphology and internal structure of the final beads were evaluated both by scanning and transmission electron microscopy. The average particle size slightly increased with the increasing DBP/seed latex and monomer/seed latex ratios. By keeping the particle uniformity, the size of carboxyl carrying-particles could be adjusted in a relatively wider range (i.e. 3–13 μm) by the selection of seed latex size. Titratable MAA contents between 69 and 181 mg g −1 were found for the particles produced under different conditions. Highly porous and carboxyl functionalized-uniform particles were obtained by starting from the polystyrene seed particles having number-average size and number-average molecular weight of 6.2 μm and 0.58×10 4, respectively. The smaller seed latices with higher molecular weights led to the synthesis of carboxyl carrying-particles with a non-porous surface and an internal part with crater-like porosity. In the case of porous particles, the surface porosity decreased significantly with the decreasing monomer/seed latex ratio and DVB feed concentration. Low monomer/seed latex ratios also resulted in a particle interior with crater-like pore structure.

Synthesis of composite latex particles filled with silica

Encapsulation of silica nanoparticles was performed by dispersion polymerization of styrene, butyl acrylate and butyl methacrylate in aqueous alcoholic media. Following previous works 1-3) , the silica beads were first modified by reacting on their surface the 3-trimethoxysilyl propyl methacrylate coupling agent (MPS). In every case, the silica beads are all surrounded by polymer giving composite latex particles filled with silica. Each composite particle contains from one to a great number of silica beads. Changing the size or the concentration of the silica beads, and the experimental conditions for the synthesis of the polymer particles enables to control this number. One can take benefit of this to synthesize model composite particles with controlled compositions.

Simulation of a Particle Formation Stage in the Dispersion Polymerization of Styrene

A model was proposed for simulation of a particle formation stage in the dispersion polymerization of styrene in ethanol. The role of poly(N-vinylpyrrolidone) molecules grafted by a polystyrene oligomer (PVP-g-PS) was taken into consideration for the particle stabilization. The model was derived based on the following mechanism: (i) polystyrene molecules whose degree of polymerization is greater than jcr precipitate and form particles, (ii) particle aggregation due to the Brownian diffusion and the shear stress of the fluid continues until the amount of the PVP-g-PS molecules is enough to cover all the particle surface, and (iii) particles do not aggregate with each other once the entrire particle surface is covered with the PVP-g-PS molecules. The theoretical particle concentrations calculated using the present model under various monomer concentrations and stirring speeds were in good agreement with the experimental data.

Separation and characterization of poly(styrene-co-acrylonitrile)-graft-poly(propylene oxide) polymer stabilizer formed in dispersion polymerization of styrene and acrylonitrile in polyether

Poly(styrene-co-acrylonitrile)-graft-poly(propylene oxide) (PSAN-graft-PPO), the stabilizer formed in situ in the dispersion polymerization of styrene, acrylonitrile and macromonomer PPO maleate in PPO polyol, was separated from ungrafted copolymer PSAN by liquid chromatography. After the determination of the separation conditions by thin-layer chromatography, the effective separation of the graft polymer from copolymer PSAN was achieved by liquid column chromatography. The graft efficiency and the composition of the graft polymer was determined by UV and 1H NMR, and the formation characteristics of the graft polymer are discussed. © 2001 Society of Chemical Industry

Simulation of Particle Growth in the Dispersion Polymerization of Styrene: The Termination Rate Constant in Particles

A model is proposed for simulating the particle growth in the dispersion polymerization of styrene in ethanol. The model is based on the following assumption: (i) the termination reaction in an ethanol-phase and the chain-transfert reactions in the ethanol-phase and particles can be neglected, (ii) the mean volume of the radicals captured by particles is approximately equivalent to that of monomeric radical, and (iii) the termination rate constant in particles is β gel times that of the ethanol-phase. The experimental results of the conversion, the particle diameter and the particle number measured as the reaction time of 2 h were used to determine the initial conditions. When the termination rate constant in particles was taken to be about 1/130 of that of the ethanol phase, the calculation results of the conversion and the particle diameter were in good agreement with the experimental data.

Encapsulation of aluminum flakes by dispersion polymerization of styrene in a nonaqueous system with reactive surfactants

Dispersion polymerization of styrene in ethanol was carried out to encapsulate aluminum flakes. The effects of three reactive surfactants, two anionic and one nonionic, were investigated. It was confirmed prior to encapsulation that these surfactants did not polymerize by themselves but did promote polymerization of styrene. The capsules obtained were characterized with respect to the morphology and mean size. The encapsulating efficiency of the polymer of the wall material, the wall thickness, and the molecular weight distribution were measured. The effects of the concentrations of styrene monomer and reactive surfactants on these characteristics were determined and discussed. Aluminum flakes were coagulated to form secondary particles and they were covered with fine polymer particles, which were precipitated in the continuous phase. To improve encapsulation, the auxiliary addition of nonionic surfactant was attempted. By controlling those concentrations, capsules covered with polymer layer were prepared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 675–683, 2001

Preparation of core-shell polystyrene-polyimide particles by dispersion polymerization of styrene using poly(amic acid) as a stabilizer

Preparation of core-shell polystyrene-polyimide particles by dispersion polymerization of styrene using poly(amic acid) as a stabilizer