Microemulsion Polymerization Of Styrene Research Articles

Kinetic events of (micro)emulsion polymerization of styrene

Integro-differential (ID) model approach has been tested on the o/w microemulsion polymerization (MEP) of styrene (S). The effect of macroinimer (MIM), time and temperature on the MEP kinetics has been modeled. The S-shaped conversion–time curves appear in the studied runs. A presented approach with four states (conversion, active and inactive particles and micelles) is followed with conversion, temperature and additive concentration, to recognize the main events occurring in styrene MEP. The existence of diffusive (vitreous) effects has been questioned. Furthermore, the problem of understanding some underlying phenomena in MEP is addressed, with an ID approach combining simple notions and concepts from microemulsion kinetics. The procedure is applied mostly to previously reported experimental data on the polymerization of styrene (S) initiated by peroxodisulfate and peroxodisulfate/sodium thiosulfate (STS) redox system, stabilized with ionic emulsifier sodium dodecyl sulfate (SDS). It was found that the nucleation rate does not follow a linear, but a bell-shaped curve. This is the reason why the rate of polymerization versus conversion curve shows the two nonstationary-rate intervals. The addition of MIM decreases both the particle nucleation and the growth events.

Main events occurring in styrene microemulsion polymerization

ABSTRACTA previously presented model with four states (conversion, active and inactive particles and micelles) is further tested with conversion versus time experimental data at 50, 60, and 70°C, to recognize the main events occurring in styrene microemulsion polymerization. The S‐shaped conversion–with no overprediction‐ and the bell‐shaped active particles number concentration–evidencing diffusive effects at late stages–versus time data, are well described by the proposed model. It was found that: (i) transfer of monomer and surfactant from micelles to particles occurs, (ii) the capture of radicals by micelles is the only cause of particle nucleation, (iii) the rate coefficient of radical‐entry‐to‐micelles is much smaller than that of exit‐from‐particles, and (iv) no coagulation between particles was detected. The Arrhenius dependency on temperature of the kinetic rate parameters is also reported. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41720.

The synthesis of translucent polymer nanolatexes via microemulsion polymerization

The potential of an extremely hydrophobic cobalt(II) catalyst for the synthesis of polymer nanolatexes in microemulsion polymerization is investigated. Colloidally stable nanolatexes have been successfully synthesized in microemulsion polymerization of styrene, butyl methacrylate, and 2-ethylhexyl methacrylate and in the presence of bis[(difluoronoryl)-diphenylglyoximato]cobalt(II). The average particle diameter can be reduced from 50nm to approximately 10nm in the presence of minor quantities of the cobalt(II) complex. The small particle size, combined with the relatively narrow particle size distribution, results in nanolatexes that are virtually transparent in appearance. Furthermore, the nucleation efficiency can be enhanced by up to two orders of magnitude, corresponding to approximately 1 particle nucleated for every 101 micelles. This represents a significant improvement as in microemulsion polymerization generally 1 particle is nucleated for every 103 micelles.

Preparation of core-shell polymeric nanocapsules containing liquid cores via redox interfacial-initiated microemulsion polymerization

AbstractIn this work, polystyrene (PSt) nanocapsules were successfully prepared by one-stage redox Interfacial-initiated inversed micro-emulsion polymerization of styrene (St), the cumene hydroperoxide (CHPO) and tetraethylenepentamine (TEPA) as the redox initiation pairs. The water-soluble TEPA acted as the reducing component and the oil-soluble CHPO as the oxidant component of the redox initiation system. The primary radicals were produced mainly at the oil/water interface to initiate the polymerization of styrene (St). Core-shell polymeric PSt nanocapsules were obtained by one-stage polymerization via this method, which was supported by the techniques of transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The particle size and polydispersity index (PDI) of nanocapsules were determined by dynamic light scattering (DLS). The results demonstrated that interfacial-initiated inversed microemulsion polymerization to form core-shell nanocapsules containing liquid cores by one-stage is successful.

The production of high polymer to surfactant microlatexes

AbstractStarved‐feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1‐pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48–54, 2010

Preparation of Halloysite Nanotubes/Polystyrene (HNTs/PS) Core‐shell Particles via Soap‐less Microemulsion Polymerization

Halloysite nanotubes/polystyrene (HNTs/PS) inorganic/organic core‐shell particles were prepared via a convenient soap‐less microemulsion polymerization. The inorganic cores were pre‐treated with allyl alcohol (AA) and the polymer shells were prepared successfully by the facile soap‐less microemulsion polymerization of styrene (St) with the allyl alcohol‐modified halloysite nanotube (AA‐HNT) nanoparticles as seeds, and potassium persulfate (KPS) as initiator in water. The products were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The morphologies of the HNTs/PS core‐shell particles were characterized by transmission electron microscopy (TEM). The mechanism of the nucleation is also mentioned.

Characterization and application of magnetic P (St-co-MAA-co-AM)/SiO2 composite microspheres

A sol–gel procedure was used to cover the magnetic P (St-co-MAA-co-AM) microspheres with a SiO2 layer, forming MMS/SiO2 composite micospheres. The composite spheres were synthesized by a two-step process. First, magnetic P (St-co-MAA-co-MA) microspheres (MMS) were prepared by microemulsion polymerization of styrene (St), methacrylic acid (MAA) and acryamide (AM) in the presence of magnetic fluid. In the next step, MMS/SiO2 spheres were obtained by addition of tetraethyl orthsilicate (TEOS) to the mixture of MMS, ammonium hydroxide and ethanol. The morphology, structure and properties of the MMS/SiO2 were characterized and the results indicate that the MMS/SiO2 spheres are about 2 μm in size with superparamagnetic behavior. The surface of the MMS/SiO2 spheres was functioned with –COOH successfully. Bioconjugation to IgG was also studied.

Differential microemulsion polymerization of styrene: A mathematical kinetic model

AbstractA mathematical model has been developed for the differential microemulsion polymerization of styrene. In the model, both homogeneous and heterogeneous nucleation mechanisms are considered. It is confirmed that the predictions of the particle size and the fractional conversion by the model are in good agreement with the experimental data. It is indicated that the particle size of polystyrene decreases with an increase in the amount of the initiator or surfactant. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Facile preparation of monodispersed core/shell zinc oxide@polystyrene (ZnO@PS) nanoparticles via soapless seeded microemulsion polymerization

Monodispersed core/shell zinc oxide@polystyrene (ZnO@PS) nanoparticles with chemical bonds between the inorganic core and the polymer shell were prepared successfully by the facile soapless microemulsion polymerization of styrene (St) with the oleic acid modified zinc oxide (OA-ZnO) nanoparticles as seeds, and potassium persulphate (KPS) as initiator in water. The products were characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The mechanism of the nucleation was also mentioned. The ZnO@PS nanoparticles could be well-dispersed in water and the emulsion was found to be remarkably stable. Ultraviolet–visible (UV–vis) analysis showed that the composites had high absorption in the ultraviolet region and low absorption in the visible region.

Preparation and characterization of magnetic P(St-co-MAA-co-AM) microspheres

In this study, magnetic polymer-coated microspheres were prepared by the microemulsion polymerization of styrene (St), methacrylic acid (MAA), acryamide (AM) in the presence of emulsifiers with the size of 1–5 μm. The magnetic material (i.e. Fe 3O 4) coated with oleic acid used in the preparation of the microspheres was synthesized in a classical co-precipitation procedure. The morphological and magnetic properties of the microspheres were investigated by different techniques (i.e. TEM, TGA, optical microscopy, vibrating sample magnetometer). The results indicated that the magnetic microspheres were superparamagnetic, well shaped spheres, mono-dispersed with abundant functional groups on the surfaces of the magnetic microspheres and good thermal stability. The microspheres could be linked well with the avidin and FITC antibody.

Monte Carlo simulation of microemulsion polymerization

Monte Carlo simulation of chemically reacting systems based on the master equation was used to describe the stochastic time evolution of the microemulsion polymerization system. A model was developed to demonstrate its applicability for hexyl methacrylate and styrene microemulsion polymerization. The properties of final latex, such as the particle size and molecular weight distributions were obtained simultaneously. The polymerization behavior and properties of final latexes were well reproduced. The model is valuable in confirming or elucidating the various mechanisms in the polymerization. The entry and desorption mechanism was well established to account for the polymerization kinetics. The general polymerization behavior of hydrophobic monomer in microemulsions was properly simulated by the model proposed.

The Kinetic and Mechanistic Role of Oil-Soluble Initiators in Micro- and Macroemulsion Polymerizations

The kinetic and mechanistic role of oil-soluble initiators in micro- and macro- (conventional) emulsion polymerization was discussed in comparison with that of water-soluble initiators. The rate of microemulsion polymerization of styrene initiated by oil-soluble azo-type initiators such as 2,2‘-azobis(isobutyronitrile) was found to be about 1/3 of that initiated by water-soluble initiators such as potassium persulfate even with the same rate of radical production in both systems. The reason for this was discussed in terms of the location of initiator but is still uncertain. In the macroemulsion polymerization of styrene initiated by oil-soluble azo-type initiators, on the other hand, the fraction of initiator dissolved in the water phase was demonstrated to be responsible for particle formation, but which portion of initiator partitioned into the water phase or into the polymer particles mainly participates in particle growth is still equivocal, although this problem has been long discussed.

Cosurfactant effects on the microemulsion polymerization of styrene

The polymerization of styrene in o/w microemulsions stabilized with dodecyltrimethylammonium bromide (DTAB) with or without cosurfactant ( n-butanol, n-hexanol or n-octanol) is examined here. The addition of a cosurfactant enhances the one-phase region in the order: n-butanol > n-hexanol > n-octanol. The kinetics of polymerization slows down in the presence of the alcohol. With the alcohol, the molar masses increase, but no particular trend was noticed on particle size of the lattices. However, by changing the surfactant counter-ion to chloride, alcohol effects on the kinetics almost vanish. Possible explanations to these results are given here. To cite this article: J.E. Puig et al., C. R. Chimie 6 (2003).

Preparation and characterization of polymer-coated core–shell structured magnetic microbeads

Composite microbeads consisting of polymer-coated iron oxide nanoparticles are prepared by the microemulsion polymerization of styrene, divinyl benzene and methacrylic acid in the presence of emulsifiers. Fourier transform infrared spectrometer analysis indicates the presence of –COOH groups and Fe 3O 4 of the microbeads. The amount of –COOH groups localized on the surface, which is about 0.15 mmol/g, is determined by conductometric titration. Transmission electron microscope picture reveals that the microbeads have a core–shell structure. The dissolving experiments of microbeads in hydrochloric acid and toluene further identify the core–shell structure. Optical microscope indicates that the magnetic microbeads have uniform and spherical forms with the size of 1–5 μm. Magnetic sensitivity measurement indicates that the microbeads can be used conveniently. Magnetic property measurement shows very little residual magnetization and coercivity, which are below 0.5 emu/g and around 15 Oe, respectively. The magnetic properties are greatly related to the particle sizes. The thermal gravity analysis result shows the improvement of thermal stability. The experiment of immobilized antibody indicates that the functional groups on the surface are appropriate.

Investigation of the Peak Width of Polystyrene Prepared by Rotating‐Sector Polymerization in Microemulsion

AbstractStyrene was polymerized by intermittent photoinitiation (at a constant sector speed and a light to dark ratio of 1:5) in microemulsion. The molecular weight distribution was measured by size‐exclusion chromatography and turned out to be extremely well structured. When the points of inflection were used for the calculation of the rate constant of propagation in analogy to pulsed‐laser polymerization/size‐exclusion chromatography (PLP‐SEC), values were obtained which were lower than those accepted for bulk polymerization but good agreement was achieved with a slightly modified equation. The absolute peak width (introduced as the difference between two successive points of inflection) turned out to be an invariant quantity no matter which type of distribution curve (number, molar mass, or hyper distribution) was analyzed, thus demonstrating the Poissonian character of the peaks. Furthermore, the relative peak widths (defined as the ratio of two successive points of inflection) for the first peak scattered between 1.35–1.45, those for the second peak between 1.26–1.30. After subtracting the respective value for the theoretical peak width, the same value for the first and second peaks was obtained for all experiments over a broad range of experimental parameters. As the appearing peaks are well resolved and narrow, the influence of axial dispersion on the results is, therefore, conclusively demonstrated. A simple procedure for the direct determination of axial dispersion is presented based on the relative peak widths and the additivity of the peak variances. The invariance of the peak widths is an easily verifiable theoretical and experimental prerequisite for this procedure. Comparison of GPC traces of a microemulsion polymerization of styrene (t0 = 1.4 s, [M] = 4.326 mol · l−1; light‐to‐dark ratio 1:5; full line) and of a standard mixture (styrene, peak masses: 1 950, 89 400, 993 000; dashed line).imageComparison of GPC traces of a microemulsion polymerization of styrene (t0 = 1.4 s, [M] = 4.326 mol · l−1; light‐to‐dark ratio 1:5; full line) and of a standard mixture (styrene, peak masses: 1 950, 89 400, 993 000; dashed line).

Microemulsion polymerization of styrene in the presence of macroinimer

The kinetics of o/w electrostatically and sterically-stabilized microemulsion polymerization of styrene with and without macromonomeric azoinitiator (macroinimer; MIM) have been investigated. The microemulsion polymerization stabilized by the ionic emulsifier sodium dodecyl sulfate (SDS) or the non-ionic emulsifier Tween 20 (Tw 20) was initiated by ammonium peroxodisulfate (APS)/sodium thiosulfate (STS) redox system. The rate of polymerization vs. conversion curve shows the two non-stationary rate intervals. This behavior is a result of two opposing effects, the continuous particle nucleation and the decrease of monomer concentration at the reaction loci. The addition of MIM favors the additional particle nucleation. The sterically (Tw 20)-stabilized microemulsion polymerization is much faster than that of the electrostatically (SDS)-stabilized microemulsion polymerization. This was attributed to the higher Tw 20 concentration and increased solubilization of MIM and comonomer concentration in the polymer particles. The formation of initial large polymer particles is attributed to the intensive agglomeration polymer particles with monomer droplets. The continuous decrease in the average size is mainly attributed to the additional particle nucleation.

Particle Nucleation and Growth Mechanisms in Styrene Microemulsion Polymerization

A water‐insoluble dye was used to study nucleation and growth of particle nuclei in styrene microemulsion polymerizations, stabilized by sodium dodecyl sulfate/1‐pentanol and initiated by sodium persulfate (SPS). Both the rate of polymerization and concentration of latex particles increase with an increase in the initial SPS concentration ([SPS]0). Least‐squares best fitting experimental data with a modified Morgan‐Nomura model leads to the conclusion that the limited flocculation of latex particles plays an important role in the reaction system. The weight percentage of dye incorporated into latex particles (Pdye) increases with the progress of polymerization. This implies that particle nucleation takes place continuously throughout the reaction. At constant monomer conversion, Pdye decreases with increasing [SPS]0, which is attributed to the increased probability of particle formation in the aqueous phase with [SPS]0. Measurements of zeta potential of latex particles and polymer molecular weight were al...

A Simulation Method to Predict Time-Evolution of Particle Size Distribution in Microemulsion Polymerization of Styrene

The method for simulating the time-evolution of the particle size distribution of polymer particles generated in the O/W microemulsion polymerization of styrene initiated by a water-soluble initiator is proposed based on the following kinetic model: The radicals generated in the aqueous phase enter the micelles, propagate therein and transform them into new polymer particles with (1) negligible bimolecular termination in the aqueous phase, and with (2) negligible entry of the second radical into the preformed polymer particles, and hence, (3) propagation of growing radicals stops only by a chain transfer reaction to monomer, (4) growth of polymer particles stops only by the desorption of the radicals generated by chain transfer out of the particles, and (5) the radicals produced by chain transfer may desorb from the particle or initiate propagation in the same particle. The average diameter calculated from the simulated particle size distribution agrees well with that measured experimentally by dynamic light scattering. The simulated particle size distribution agrees with that measured experimentally with a transmission electron microscope.

Ultrasonically induced microemulsion polymerization of styrene

In this paper, ultrasonically induced microemulsion polymerization of styrene was successfully performed, possessing many merits such as high polymerization rate, the formation of small latex particles with a narrow size distribution, the absence of initiator and relatively low surfactant concentration. The monomer conversion reached 70% in 1 h, and the average diameter of polystyrene (PS) latex was about 30 nm which could be prepared with 3% surfactant (sodium dodecyl sulfate, SDS) concentration. The molecular weight of PS was around 10 6 and the poly-distribution index was 1.06, indicating a very narrow distribution. Several influencing factors were investigated in detail, showing that ultrasonically induced microemulsion polymerization is a new route to prepare PS nanoparticles.

Kinetics and mechanisms of o/w microemulsion polymerization of styrene

To clarify the kinetics and mechanisms of o/w microemulsion polymerization, the o/w microemulsion polymerizations of styrene were carried out with different kinds and types of initiators and surfactants. The number of polymer particles and the molecular weight of polymer formed were not affected by the kinds and types of initiators and surfactants. The rate of polymerization with different kinds of azo-type oil-soluble initiators with widely different water-solubility was almost the same, but was much lower than that with KPS. A kinetic model proposed by us could mostly explain the kinetic behavior except for the difference in the polymerization rate with KPS and that with oil-soluble initiators.