Poly(n-hexyl methacrylate) polymerization in three-component microemulsion stabilized by a cationic surfactant (original) (raw)
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Synthesis and characterization of poly(n-hexyl methacrylate) in three-component microemulsions
European Polymer Journal, 2001
The polymerization of n-hexyl methacrylate in three-component microemulsions stabilized with dodecyltrimethylammonium bromide is examined here as a function of the concentration of a water-soluble (V-50) and an oil-soluble (2, 2-azobisisobutyronitrile) initiators, of monomer concentration in the parent microemulsions and temperature. At high temperatures and high initiator concentrations, only two reaction rate intervals are observed; however, at low temperatures and low
Polymerization of methacrylate in a W/O microemulsion stabilized by a methacrylate surfactant
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999
A water-in-toluene microemulsion stabilized by the polymerizable surfactant didecyldimethylammonium methacrylate has been used to form polyelectrolyte particles. The microemulsion was photopolymerized using AIBN as the initiator, resulting in aggregates having hydrodynamic diameters of 11 nm, starting with 5 -6 nm initial nanodroplets with and without added sodium methacrylate (NaMA). The dried latexes have a diameter of 6 nm up to a [NaMA]/[surfactant] mole ratio (R) of 0.5, but 12 nm for R= 1.0. For R =0 -0.5, the maximum degree of polymerization was 50%, but it was 83% for R= 1.0. The polydispersity decreases with increasing R, while the film-forming tendency of the latexes increases.
Journal of Polymer Science Part A: Polymer Chemistry, 2004
Nanoscale poly(methyl methacrylate) (PMMA) particles were prepared by modified microemulsion polymerization. Different from particles made by traditional microemulsion polymerization, the particles prepared by modified microemulsion polymerization were multichain systems. PMMA samples, whether prepared by the traditional procedure or the modified procedure, had glass-transition temperatures (T g 's) greater than 120°C and were rich in syndiotactic content (55-61% rr). After the samples were dissolved in CHCl 3 , there were decreases in the T g values for the polymers prepared by the traditional procedure and those prepared by the modified process. However, a more evident T g decrease was observed in the former than in the latter; still, for both, T g was greater than 120°C. Polarizing optical microscopy and wide-angle X-ray diffraction indicated that some ordered regions formed in the particles prepared by modified microemulsion polymerization. The addition of a chain-transfer agent resulted in a decrease in both the syndiotacticity and T g through decreasing polymer molecular weight.
Particle Nucleation during Microemulsion Polymerization of Methyl Methacrylate
Macromolecules, 1994
The evolution of the reaction conversion and particle size distribution during the microemulsion polymerization of methyl methacrylate (MMA) is used to determine the particle nucleation mechanisms. A pseudo-3-component oil-in-water microemulsion is formed with water, MMA, and a mixture of dodecyltrimethylammonium bromide (DTAB) and diodecyldimethylammonium bromide (DDAB) in a 3:l weight ratio as surfactant. Polymerization is initiated with either an oil-soluble or a water-soluble initiator and conversion followed either by measurement of the unpolymerized monomer concentration in samples taken during the reaction or by direct on-line densimetry. A two-stage process is observed. The first stage, described by a very slow increase in conversion, is attributed mainly to homogeneous nucleation, and the second stage, characterized by a much higher rate of conversion, involves continuous nucleation and is governed mainly by a micellar-entry mechanism.
Journal of Research Updates in Polymer Science, 2016
Miniemulsion polymerization is widely used to produce polymer nanoparticles. In many applications, it is important to ensure the narrow particle size distribution of the final product, which means that secondary micellar and homogeneous nucleation must be avoided during the reaction course. The present study proposes the use of hydrophilic comonomers to inhibit the occurrence of secondary particle nucleation in miniemulsion polymerizations of methyl methacrylate. Acrylic acid, metacrylic acid, 2-hydroxy ethyl methacrylate and methacrylamide were used as hydrophilic comonomers. It was observed that the use of small amounts of hydrophilic comonomers in miniemulsion polymerizations promoted by oil-soluble initiators could prevent secondary particle nucleation and lead to products with more homogeneous particle size distributions.
Cationic Microemulsion Polymerization of Alkyl Acrylates
Materials Sciences and Applications, 2010
Here we present the polymerization of n-butyl acrylate (BA), ethyl acrylate (EA) and methyl acrylate (MA) in tri-component microemulsions, using a cationic surfactant such as dodecyl trimetyl ammonium bromide in water, as a function of temperature, initiator type and, monomer and initiator concentration. The final latexes are transparent and blue color, with particle size ranging between 20 and 60 nm determined by quasielastic light scattering (QLD) and SEC molar masses of the order of 10 6 g/mol. Reaction times are short and reaction rates are high with final conversions between 70 and 98% depending on the monomer and the reaction conditions.
2011
Here, we present the oil/water (O/W) microemulsion polymerization in three-component microemulsions of n-butyl acrylate, ethyl acrylate, and methyl acrylate, monomers with similar chemical structures but different water solubilities using the cationic surfactant dodecyl trimethyl ammonium bromide. The effects of monomer water solubility, initiator type and initial monomer concentration on the polymerization kinetics were studied. Reaction rates were high with final conversions between 70 and 98% depending on the monomer and reaction conditions. The final latexes were bluish, with a particle size ranging between 20 and 50 nm and polymer with molar masses in the order of 10 6 g mol À1 . Increasing monomer water solubility resulted in a slower reaction rate, larger particles and a lower number density of particles. A higher reaction rate, larger average particle size and higher particle number density were obtained by increasing the monomer concentration.
Microemulsion and conventional emulsion copolymerizations of methyl methacrylate with acrylonitrile
Journal of Applied Polymer Science, 2002
The microemulsion (ME) and conventional emulsion (CE) copolymerizations of methyl methacrylate (MMA) with acrylonitrile (AN) are carried out at 70°C by employing sodium lauryl sulphate (SLS) and n-octanol (OA) as surfactant and cosurfactant, respectively, and potassium persulphate (KPS) as initiator. The copolymerization reactions are arrested at lower conversions, and the copolymers prepared are characterized by FTIR, NMR, TG/DTA, and GPC techniques. The reactivity ratios for microemulsion and conventional emulsion copolymerizations are evaluated by Fineman-Ross (F-R), Kelen-Tüdös (K-T), and Mayo-Lewis (M-L) graphical methods. The K-T method yields the reactivity ratios of MMA (rMMA) and AN (rAN) as 2.03 ± 0.02 and 0.10 ± 0.02, and 1.97 ± 0.02 and 0.13 ± 0.02, respectively, for ME and CE copolymerization methods. The results are compared with the literature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1503–1510, 2002
European Polymer Journal, 2004
In this study, MMA/BMA copolymer nanoparticles were synthesized in oil-in-water microemulsions that were stabilized by sodium dodecyl sulphate (SDS) and initiated by potassium persulphate KPS. Maleic acid terminated poly(N-acetylethylenimine) (PNAEI) with two different chain lengths was also included in the recipe, as a cosurfactant and a comonomer. FTIR and 1 H-NMR proved incorporation of the macromonomer in the structure. High polymerization yields were achieved upto 98%. The viscosity average molecular weights of the copolymers were in the range of 2.77-5.50 · 10 5 . The glass transition temperatures of these copolymers were between 50.0 and 63.9°C. The average diameter of nanoparticles were in range of 40-96 nm. It was possible to produce nanoparticles smaller than 100 nm and with narrower size distributions by using much lower concentrations of SDS by including the macromonomers in the microemulsion polymerization recipe.
Kinetics of emulsifier‐free emulsion polymerization of methyl methacrylate
Journal of Applied Polymer Science, 1996
The influences of polymerization temperature, initiator and monomer concentrations, ionic strength of the aqueous phase, as well as ethylene glycol dimethacrylate (EGDM) comonomer, on the kinetics of the emulsifier-free emulsion polymerization of methyl methacrylate (MMA) and on the properties of the resulting poly(methy1 methacrylate) (PMMA) lattices were studied. The polymerizations were carried out using potassium persulfate (KPS) as the initiator. Monodisperse PMMA lattices with particle diameters varying between 0.14-0.37 pm and polymer molecular weights of the order 0.4 X lo6 to 1.2 X lo6 g/ mol were prepared. The initial rate of polymerization increases with increasing temperature, KPS-MMA mole ratio, EGDM content, or with decreasing ionic strength of the aqueous phase. It was shown that the bead size can be limited by reducing the monomer concentration or by using the cross-linking agent EGDM. The ionic strength of the aqueous phase has a dominant effect on final particle diameter and polymer molecular weight. The uniformity of the latex particles increases as the temperature increases or as the initiator concentration decreases. The experimental results can be reasonably interpreted by the homogeneous nucleation mechanism of the emulsifier-free emulsion polymerization of MMA. 0 1996 John Wiley & Sons, Inc.