Microemulsion polymerization of butyl acrylate. IV. Effect of emulsifier concentration

Capek, Ignác; Potisk, Pavol

doi:10.1002/pola.1995.080331014

Cited by 46 publications

(21 citation statements)

References 30 publications

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“…When one considers the hydrophobic nature of St, the migration of monomeric radicals into the aqueous phase is not favored. This step could be facilitated by a chaintransfer reaction from the primary radical to an emulsifier molecule, 21,22 which may diffuse into the aqueous phase very easily through the fast dynamic exchange of emulsifier molecules between the oil/water interface and the aqueous phase. The monomer conversion achieved by the thermally initiated polymerization is about two orders of magnitude lower than that achieved by the peroxodisulfate-initiated polymerization.…”

Section: Role Of Thermal Polymerizationmentioning

confidence: 99%

Effect of temperature on styrene emulsion polymerization in the presence of sodium dodecyl sulfate. II

Capek

Lin

Hsu

et al. 2000

J. Polym. Sci. A Polym. Chem.

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Section: Role Of Thermal Polymerizationmentioning

confidence: 99%

Effect of temperature on styrene emulsion polymerization in the presence of sodium dodecyl sulfate. II

Capek

Lin

Hsu

et al. 2000

J. Polym. Sci. A Polym. Chem.

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“…The main location of NMA at the interfacial layer decreases the monomer concentration at the reaction loci (dilution effect) 22 and the rate of polymerization as well. The largest Rp,max, 2 or smallest R 112 for MMA results from increased agglomeration of particles which first decreases Rp,max,l (due to increased deactivation of reaction loci) and later increases Rp.max, 2 (due to accumulation of radicals in the large particles).…”

Section: Kinetic Parametersmentioning

confidence: 99%

Microemulsion Polymerization of Alkyl (Meth)acrylates Initiated by UV Light

Capek

1999

Polym J

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ABSTRACT:Radical polymerizations of polar unsaturated monomers ethyl acrylate, methyl methacrylate and nonyl methacrylate in an o/w microemulsion photoinitiated by a UV light were investigated. Polymerizations were conducted at low temperature to follow the effects of a varied solubility of monomer (coemulsifier) and/or diffusional degradation of monomer droplets on the kinetic and colloidal parameters. The rate versus conversion curve showed four regions with two rate maxima ca. at 5% to 20% and 50 to 70% conversion. The first rate maximum results from abrupt decrease of the monomer concentration at microemulsion loci and the second one from the increased accumulation of radicals in the latex particles. The higher polymerization rate of ethyl acrylate compared to that for methyl methacrylate or nonyl methacrylate was attributed to higher monomer concentration at reaction loci and propagation rate constant and lower quenching rate. The rate of polymerization was found to increase with incident light intensity and was most pronounced with nonyl methacrylate. The reaction order (the dependence of the rate of polymerization or the number of particles on the incident light intensity) was taken as a measure of particle nucleation efficiency. Particle size distribution was observed to be very narrow at low conversion and increased with increasing conversion.KEY WORDS Microemulsion j Polymerization I Alkyl (Meth)acrylates I Kinetics I Particle I Nucleation/ Microemulsion and miniemulsion polymerizations offer convenient access to well-defined microlatex particles being typically one order of magnitude smaller than polymer particles obtained by conventional emulsion polymerization. The fine monomer emulsion exhibits a large interface between monomer droplets and the aqueous phase. Under such conditions, continuous nucleation up to (very) high conversion is operative. There is no apparent constant rate period in the o/w microemulsion or miniemulsion polymerization. 1 -3 Ugelstadt et a/. 4 clearly demonstrated that monomer droplets could effectively compete with monomer-swollen micelles for capture of free radicals generated in the aqueous phase when the total surface area of the droplets became large enough. In conventional emulsion polymerization, the principle locus of particle nucleation is the aqueous phase or the monomer swollen micelles depending on the degree of water solubility of the monomers, an initiator and amount of emulsifier. Monomer droplets are considered only as monomer reservoir supplying monomer to the growing polymer particles. However, the small size of the monomer droplets (micro-or minidroplets) enables them to become the principle locus of particle nucleation ..The principle behind the formation ofmicroemulsions (droplet size I 0-50 nm) is penetration of coemulsifier into the water/oil interface, thereby decreasing surface tension and increasing interface area. Coemulsifier also decreases the rigidity of interface film due to increasing the molecular disorder. Coemulsifier promotes the formatio...

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“…We have earlier reported that n n lies well below 0.5 for the small PBuA particles with diameter around and below 50 nm. 40,41 In the present paper n n is ca. 0.9 for the weight ratio BuA/SDS (9.0/ 20) = 0.45.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of Styrene and Butyl Acrylate Polymerization in Anionic Microemulsions in Presence of Layered Silicates

Fialová

Capek

Ianchiş

et al. 2007

Polym J

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The effect was studied of various layered silicates (sodium montmorillonite and different organomodified montmorillonites) on kinetics of styrene (St) and butyl acrylate (BuA) in anionic (sodium dodecyl sulfate) microemulsion polymerization. The dependence of the polymerization rate on the conversion exhibits two rate intervals. The presence of layered silicates affects the conversion and polymerization rate of both St and BuA. The size of polymer particles increases with polarity of Cloisite and the increase is more pronounced in poly(butyl acrylate) particles. The kinetic, colloidal and molecular weight parameters are influence both by the monomer and layered silicate polarities. Different approaches (Ugelstadt, Nomura and Gilbert models) were used for evaluation of polymerization kinetics. The desorption constants (k des ) decrease in presence of the studied layered silicates (Cloisite Na, Cloisite 30B, Cloisite 20A). The decreasing values of the desorption constants in the presence of clays; demonstrate a clear effect, which implies the decreasing of the probability of the radical exit from particles in the presence of the layered silicates.KEY WORDS: Microemulsion Polymerization / Layered Silicates / Kinetics / Nanolatexes / Nanocomposites / The synthesis of nanoclay composites from dispersed systems exhibit an increased interest in the last years. The main reasons include the encapsulation of layered silicates, nanolayer stabilization, in situ polymerization of the monomers in intergalleries of the layered silicates and the possibility of obtaining hybrid particles and nanoparticles.1-5 Even through the numerous reports about emulsion, miniemulsion and suspension polymerization of different monomers in presence of layered silicate can be found in the literature, the kinetics data are rather rare. 1,6,7 Some other papers 8,9 deal with the bulk polymerization of selected monomers, for example methyl methacrylate in presence of montmorillonite (MMT). It was found that an optimal ratio of MMT/initiator (benzoyl peroxide) promotes an increase in the polymerization rate of methyl methacrylate. 8Presence of an organomodified montmorillonite also increases the polymerization rate of styrene in bulk polymerization. 9 In the case of emulsion polymerization of styrene the reaction rate is enhanced by the presence of sodium montmorillonite, however the study handles only one level of inorganic filler. 10In the miniemulsion polymerization of styrene in presence of laponite the silicate layers can be on the surface of the particle but also inside the emulsion-latex particle depending on the initiator nature. 7 In suspension polymerization of styrene in presence of different organophilic montmorillonites silicates are likely also inside the particle.11 For suspension polymerization of methyl methacrylate in presence of organophilic montmorillonite the clay layers are situated both inside and on the surface of the latex particles.12 In this case, the kinetics of the monomer polymerization is much influenced by the presenc...

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Microemulsion polymerization of butyl acrylate. IV. Effect of emulsifier concentration

Cited by 46 publications

References 30 publications

Effect of temperature on styrene emulsion polymerization in the presence of sodium dodecyl sulfate. II

Effect of temperature on styrene emulsion polymerization in the presence of sodium dodecyl sulfate. II

Microemulsion Polymerization of Alkyl (Meth)acrylates Initiated by UV Light

Kinetics of Styrene and Butyl Acrylate Polymerization in Anionic Microemulsions in Presence of Layered Silicates

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