Synthesis of monodisperse polymer suspensions with a narrow particle size distribution in the presence of water-insoluble triple block copolymers of polypropylene oxide and polyethylene oxide (pluronics)

The colloidal chemical properties of triple block copolymers of polypropylene oxide and polyethylene oxide (pluronics of various structures) were studied in comparison. All of them are shown to be surfactants but differ in interfacial tension, surface activity, surface area occupied in the adsorption layer, and adsorption layer thickness. The kinetic regularities of polymerization of styrene and methyl methacrylate were studied. The particle diameters and their size distribution were determined. Distinctions in the kinetic regularities of polymerization are shown: the shape of the conversion—time curves (for the duration of the initial and stationary stages of polymerization) and the dependences of the diameter on the surfactant concentration and monomer to water volume ratio. In the presence of the water-insoluble pluronics, the mechanism of formation of polymer—monomer particles and interfacial layer on the surface differs from that when using water-soluble surfactants, which makes it possible to distinguish these processes into an independent type of heterophase polymerization.

     

A theoretical study of the emulsion polymerization of styrene: The effect of the initial dispersion of the system on the molecular-mass distribution of polystyrene

On the basis of the mathematical model of emulsion polymerization, which takes into account the possibility of formation of polymer-monomer particles from monomer microdroplets, the molecular-mass distribution of the polymer formed in systems with different initial states of the original emulsion system (monodisperse or bidisperse system of microdroplets) is calculated. It is shown that the molecular-mass distribution of the polymer is governed by the state of the original emulsion system and the conversion of the monomer.     

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.     

Styrene polymerization in the presence of different initiators and properties of polymer suspensions

It is shown that the nature of an initiator affects the molecular mass and molecular-mass distribution of a polymer and, thus, substantially contributes to the strength and rheological characteristics of the interfacial adsorption layer formed on the surface of polymer-monomer particles and the stability of these particles during polymerization.     

Dispersion Oxidative Polymerization of Pyrrole in Aqueous Solutions of Polyvinyl Alcohol

Russian Journal of General Chemistry - Kinetics of the oxidative polymerization of pyrrole in an aqueous solution of poly(vinyl alcohol) under the action of ammonium peroxydisulfate has been...     

Structure of polystyrene latex particles determined by electron microscopy

The structures of individual polystyrene microspheres obtained in the presence of organosilicon surfactants were studied by transmission electron microscopy. The density of the macro-molecule distribution over the cross section of particles was determined. The synthesized latex particles have a core—shell structure.

     

Influence of dispersion conditions and nature of the emulsifier on the dispersity and stability of artificial polymer suspensions based on polyetherimide

New methods for producing artificial polyetherimide suspensions in the presence of domestic cationic surfactants, their mixtures, and mixtures of cationic and organosilicon surfactants were proposed. The effect of the polymer concentration in the initial solution and conditions of emulsion dispersion on the stability and particle size of the final polymer suspensions is shown. The colloidal chemical properties of the obtained polymer suspensions are considered. Conclusions about the influence of the nature and concentration of surfactants on the stability of the obtained suspensions are drawn. When using a mixture of cationic and organosilicon surfactants, polymer suspensions stable during production and storage are formed, which is explained by the formation of structural mechanical and electrostatic stability barriers in the surface layers of the particles.

     

Organocobalt chelates as initiators of emulsion polymerization of styrene

The kinetics of decomposition of organocobalt chelates in the pH range of 2.2–7.0 has been studied. It has been shown that the rate constant of decomposition of the octyl chelate complex at 20°C changes from ～3 × 10^?3 to ～6 × 10^?6 s^?1 in the above pH range. The rate constants of decomposition of complexes with ethyl, octyl, and cetyl ligands, as estimated at 20°C and pH 8.3, are 1.69 × 10^?4, 1.39 × 10^?4, and 2.42 × 10^?5 s^?1, respectively. As evidenced by emission spectrometry measurements, ～100% of organocobalt chelates with ethyl and isopropyl ligands occur in the aqueous phase, while organocobalt chelates with octyl and cetyl ligands are partitioned between monomer and aqueous phases. The rates of initiation of the emulsion polymerization of styrene have been measured by the inhibited polymerization procedure. It has been demonstrated that among three tested compounds (diphenyl picryl hydrazyl, hydroquinone, and benzoquinone), benzoquinone has been found to be a suitable inhibitor for the polymerization under study. The rates of initiation of styrene polymerization at 30°C for organocobalts with ethyl, octyl, and cyclohexyl ligands are 1.0 × 10^?7, 1.04 × 10^?7, and 3.7 × 10^?6 mol/(l s), respectively. The rate constant of decomposition of the organocobalt complex with the octyl ligand at 30°C is 2.28 × 10^?5 s^?1, and the efficiency of initiation with this complex is 0.95.     

Polymer microspheres for replacement of biological carriers in test systems operating on the principle of latex agglutination reaction

The results of the study of various modification methods of polymer microspheres for their use in immunochemical reactions as bioligand carriers are reported. Ion etching and electron microscopy were used to show that the copolymer microspheres have a porous structure non-uniform in density. The Maillard reaction was used for the first time in the modification of copolymer microspheres by dextrans of different molecular weight as a simplest way of covalent immobilization of saccharides on their surface. The physicochemical properties of polystyrene-divinylbenzene and polyglycidyl methacrylate-ethylene glycol dimethacrylate microspheres modified with diamines and dextrans were determined for the first time. The conditions under which the bioligand (diphtheria toxoid) immobilized on their surface retained the native conformation and the diagnostics obtained on their basis have high sensitivity were revealed.