Emulsifiers In Emulsion Polymerization Research Articles

Properties and Applications of Sodium (5-methyl-2-alkyl-1,3-dioxane-5-yl)-Carboxylate Synthesized with Nanosolid Superacid.

A series of novel sodium (5-methyl-2-alkyl-1,3-dioxane-5-yl) carboxylate surfactants were synthesized using nanosolid superacid SO₄²⁻/Fe₂O₃as a catalyst and characterized by ¹H NMR, IR and elemental analysis. The critical micelle concentration (CMC) of surfactants was determined and the results showed that the CMC values were less than 2.0 x 10⁻³ mol/L. Other relevant surface properties (Krafft point, emulsion stability, foam ability, degradability) were also evaluated. It was suggested that with respect to emulsion formation, foam stability and the range of application temperature, compared with traditional surfactants, the new surfactants could give better results and showed better properties when used as an emulsifier in emulsion polymerization. In addition, the surfactants were stable under neutral and alkaline conditions, and could form solid under acid condition. The solid will generate the original surfactants for reuse with alkali. Sodium (5-methyl-2-alkyl-1,3-dioxane-5-yl) carboxylate is likely to be a new type of 'environmentally friendly' surfactant.

A Novel Approach to Prepare Poly(Vinyl Acetate)/Ag Nanocomposite for Effective Antimicrobial Coating Applications

Polyvinyl acetate nanocomposites were successfully prepared based on silver nanoparticles. First, silver nanoparticles were directly prepared during the in situ emulsion polymerization of vinyl acetate monomer using AgNO3 as a source of Ag+ ions and poly(vinyl alcohol) was used for dual functions as emulsifier for emulsion polymerization and as a stabilizing agent, trisodium citrate (C6H5O7Na3) was used as reducing agent for Ag+ ions during the polymerization process. The prepared polyvinyl acetate/Ag nanocomposites were assessed using X-ray diffraction, scanning electron microscopy, Fourier transform infrared, transmission electron microscopy, and ultraviolet spectra. The antibacterial properties of the prepared polyvinyl acetate/Ag nanocomposites were investigated as antimicrobial activity against pathogenic bacteria, i.e., Staphylococcus aureus (G+ve bacteria) and Escherichia coli (G−ve bacteria). These polyvinyl acetate nanocomposites could be used as a promising material for enhanced and continuous antibacterial applications as coating and packaging materials.

Imidazoline derivatives as promising cationic emulsifiers for styrene heterophase polymerization

The colloidochemical properties of new cationic surfactants synthesized from fatty acids of palm oil and diethylenetriamine are first studied. It is found that, at solution pH below 6.0, the examined surfactants exist mainly as salts formed from protonated surfactant molecules and residues of strong acids, e.g., hydrochloric acid. In the pH range above 7.0, the protonated and nonprotonated forms of the surfactants are at equilibrium, which shifts to the nonprotonated form with an increase in pH. The analysis of interfacial tension isotherms shows that the minimum values of the interfacial tension are achieved at pH 7.0 when the concentrations of the protonated and nonprotonated forms of surfactant molecules are equal. New cationic surfactants are used as emulsifiers in emulsion polymerization of styrene. It is found that stable polystyrene latexes with narrow particle size distributions and high positive ζ potentials (as high as +68.4 mV) can be obtained at styrene concentration in an initial emulsion of 25 vol % and surfactant concentration in an aqueous phase of 2 wt %. A hydrogen peroxide-iron(II) salt redox system is used as an initiator of polymerization at component concentrations equal to 5 and 0.05 wt % of the monomer, respectively.

Synthesis and Applications of Alkylbenzene Sulfonate Gemini Surfactants

A series of anionic Gemini surfactants with the same structure except for the spacer and side chain length of the alkylbenzene sulfonate were synthesized based on dodecyl benzene and toluene. The structures of the compounds were confirmed by infrared and nuclear magnetic resonance spectroscopy, and elemental analyses. The effect of spacer and side chain length on the interfacial tension of Gemini surfactant solution was investigated by comparison of the critical micelle concentration (cmc) of the surfactants in aqueous solution using the drop volume method, and the surface tension at the cmc (γcmc). The Gemini surfactant with the best properties was used as emulsifier in emulsion polymerization of methyl methacrylate, and its foam stability was also determined.

Some aspects of nitroxide-mediated living radical polymerization of N-( p-vinylbenzyl)phthalimide

The free radical polymerization of N-( p-vinylbenzyl)phthalimide (VBP) “initiated” with the adduct of 2-benzoyloxy-1-phenylethyl and TEMPO (BS-TEMPO) or TEMPO-terminated polystyrene (PS-TEMPO) in N,N-dimethylformamide (DMF) at 125 °C was found to proceed in a living fashion, providing low-polydispersity PVBP and block copolymers of the type PS- b-PVBA, where TEMPO is 2,2,6,6-tetramethylpiperidinyl-1-oxy. Unlike TEMPO-mediated styrene polymerization, the polymerization rate slightly but distinctly depended on the adduct concentration, which was interpretable as a pre-stationary behavior. The hydrolysis of those polymers gave poly( p-aminomethylstyrene) (PAMS) and PS- b-PAMS, and further treatment of the block copolymer with hydrogen chloride provided an amphiphilic block copolymer. The polymeric amphiphile was used as an emulsifier in emulsion polymerization to produce a positively charged polymeric microsphere.

Water-Soluble Polyurethane Resins as Emulsifiers in Emulsion Polymerization of Styrene: Nucleation and Particle Growth

Polystyrene/polyurethane hybrid latex particles were synthesized by employing water-soluble (or dispersible) polyurethane resins which had been prepared from isophorone diisocyanate (IPDI), poly(1,2-propylene glycols) (PPG-750 and PPG-2000), and 2,2-bis(hydroxymethyl)propionic acid (DMPA). Two kinds of polyurethane resin were used as emulsifiers and their effect on emulsion kinetics was investigated by measuring the rate of polymerization, the particle size distribution, the number of particles, and the average number of radicals per particle. Effects of the resin concentration on the rate of polymerization and the number of particles were found have a somewhat similar kinetic behavior with exponents in the range of 0.25-0.30 and 0.60-0.70, respectively. The averge particle sizes, however, were very small (ca. 40-60 nm) and the particle size distribution showed a broad distribution. The particle nucleation period continued event over 0.7-0.8 fractional conversion of styrene. Moreover, the intial latex particle size was very large in comparison with the final particle size. Characteristic behavior of the particle nucleation and growth was mainly attributed to superior solubilizing ability and high internal viscosity of the polyurethane resin aggregates.

Polymerizable and Nonpolymerizable Isophthalic Acid Derivatives as Surfactants in Emulsion Polymerization

This article presents an initial study on the use of polymerizable and nonpolymerizable isophthalic acid derivatives as novel emulsifiers in emulsion polymerization. The polymerization process and the final latex properties are compared to latices made under the same conditions with commercial surfactants:  sodium dodecyl sulfate (SDS) and potassium pentadecanoate (C15A). The use of the difunctional isophthalic acid appears to increase the stability of the polymer dispersion. This stabilization effect was further improved by introducing polymerizable derivatives. This kind of emulsion polymerization process is a new way of creating functional nanoparticles.

A Light-Sensitive Diazosulfonate Surfactant as Emulsifier for Emulsion Polymerization

Abstract A light-sensitive diazosulfonate surfactant (Ar-N=N-SO3 −) was applied as emulsifier for emulsion polymerization. The resulting latex was photosensitive and coagulated during irradiation. Since photolysis of the anionic diazosulfonate surfactant in water occurs mainly via the corresponding cationic diazonium amphiphile (Ar-N2 +) it is concluded that a mutually charge neutralization on the latex surface could promote coagulation during photolysis. Quantitative analysis of the diazosulfonate and of the diazonium salt during irradiation and the coagulation behavior of the latex support this view.

Use of poly(styrene)-block-poly(ethyleneoxide) as emulsifier in emulsion polymerization

Poly(styrene)-block-poly(ethyleneoxide), abbreviated as (PS-b-PEO) were used as emulsifiers in emulsion polymerization of styrene and methyl methacrylate. The block copolymers had a poly(styrene) block with Mn=1000 g/mol and a poly(ethyleneoxide) block with Mn=1000, 3000 or 5000 g/mol, respectively. Stable dispersions were obtained when the PEO block molecular weight was higher than 1000 g/mol. Also the amphiphilic properties of the copolymers depended on the PEO chain length. Block copolymer micelles with hydrodynamic radii between 11 and 17nm were observed. Emulsion polymerization was performed at different block copolymer concentration at 60 and 80°C. Particle size varied between 50 and 300nm and decreased with increasing copolymer concentration. The particle size was larger at higher temperature, but the size distribution was narrower. Polymerization of methyl methacrylate gave smaller particles when compared to styrene. The dispersions were very stable towards high electrolyte concentration, but flocculation occurred at elevated temperatures. Both observations indicate that the dispersions are sterically stabilized.

Functional polymers for colloidal applications. V. Novel behavior of polymeric emulsifiers in emulsion polymerization

AbstractThe polymeric emulsifier poly(dodecyl acrylate‐co‐acrylic acid) [i.e., the sodium salt (PDA)] and monomeric emulsifier sodium dodecyl glutarate (SDG) have been synthesized. PDA and SDG are used as emulsifiers in the emulsion polymerization of styrene with both the water‐soluble initiator potassium persulfate (K2S2O8) and the oil‐soluble initiator 2,2′‐azobisisobutyronitrile (AIBN). The PDA/K2S2O8 system showed a bimodel distribution of particle sizes (2 and 0.05 μm). A bimodel particle distribution was also found for the PDA/AIBN system, but the distribution for the large particles was wide (0.1–10 and 0.07 μm). The SDG/K2S2O8 system displayed only one kind of particle size (0.05 μm), but the SDG/AIBN system also showed a bimodel distribution of particle sizes (0.05 and 5 μm). These bimodel distribution results for the PDA/K2S2O8, PDA/AIBN, and SDG/AIBN systems indicate that the polymerization sites are both in oil droplets and in micelles (polymer aggregates). This mechanism is interpreted in terms of the formation of polymer aggregates, which is supported by the results of pyrene solubilization, pyrene fluorescence, surface tension, and pyrene excimer experiments. © 1993 John Wiley & Sons, Inc.

Synthesis and Properties of Destructible Anionic Surfactants with a 1, 3-Dioxolane Ring and Their Use as Emulsifier for Emulsion Polymerization

Destructible anionic surfactants with a 1, 3-dioxolane ring were prepared and their surface properties determined. These novel surfactants contain a sulfonate group as the anionic hydrophile, and readily decompose under weakly acidic conditions. As surfactants for emulsion polymerization reactions, they are considerably superior to the conventional surfactants which give polymers containing higher contents of metals than the above surfactants.

The effectiveness of some commercial emulsifiers in emulsion polymerization I. “Soap‐free” systems, ethoxylated nonylphenols

AbstractThe initial polymerization rate of ethyl, butyl, and 2‐ethylhexyl acrylate was studied in a thermally insulated polymerization reactor. Monomers were continuously added into the reactor and the effect of variables in emulsifier and initiator concentrations was investigated. Ethyl and butyl acrylate polymerized even in absence of emulsifier. This indicated a homogeneous nucleation of particles. Ethoxylated nonyl‐phenols containing 20 and more oxyethylene units were effective in emulsion polymerization of the studied acrylic monomers.

The effectiveness of some commercial emulsifiers in emulsion polymerization II. Anionic types

AbstractThe initial polymerization rate of ethyl, butyl, and 2‐ethylhexyl acrylate was studied in a thermally insulated polymerization reactor. The monomers were continuously added into the reactor and the effect of concentration of anionic emulsifiers on the temperature increase was investigated.Alkyl(aryl)polyethylenglykolethersulfate were found to be most effective in promoting the initial polymerization rate. An inhibition action of some emulsifiers was found.

Effect of interphase surface on emulsion polymerization

A study was made of the effect of the type of monomer on kinetics and the adsorption of two types emulsifier in emulsion polymerization of lower alkylacrylates unter conditions excluding the formation of surface active oligomers. It was shown that the rate of polymerization and the length of the stationary section are functions of interphase tension at the monomer-water interface. It was established by direct measurements of the adsorption of the emulsifier directly during polymerization that it decreases on increasing the solubility of the monomer in water which accounts for the low colloidal stability of these systems during polymerization.