A. Yu. Men'shikova

Synthesis of Polypyrrole Nanoparticles by Dispersion Polymerization

The influence of pyrrole, oxidant (FeCl3), and polymeric stabilizer (polyvinyl alcohol) concentrations and of temperature on the rate of redox dispersion polymerization of pyrrole, diameter of the forming particles, and their size distribution was studied with the aim to prepare polypyrrole nanoparticles.

Direct opal-like structures consisting of monodisperse polymer particles and synthesis of the related inverse structures

Three-dimensional periodic solid-state film structures with a face-centered cubic lattice and a high degree of perfection have been prepared from monodisperse particles of styrene copolymers with methacrylic acid. It has been shown that these structures can be successfully used not only as model objects for studying specific features of light propagation in photonic crystals but also as templates for synthesizing inverse opal-like structures. The influence of the degree of hydrophilization of the surface layer of polymer particles forming a polymer template and the template synthesis conditions on the quality of an inverse opal-like TiO2-based structure has been analyzed.

Synthesis of Polymethyl Methacrylate Microspheres in the Presence of Dextran and Its Derivatives

Emulsion polymerization of methyl methacrylate initiated by a carboxyl-containing azo initiator in the presence of a polymeric stabilizer (dextran or its functionalized derivatives) was studied with the aim to prepare monodisperse microspheres of polymethyl methacrylate with surface carboxy, amido, and aldehyde groups. The optimal conditions for formation of monodisperse microspheres were found, allowing control of their diameter in the submicrometer range and of the nature and content of surface functional groups.

Monodisperse Microspheres Based on Acrolein Copolymers

Emulsifier-free emulsion copolymerization of acrolein with styrene and methyl methacrylate in the presence of potassium persulfate was developed to prepare microspheres with surface aldehyde groups. The kinetics of monomer copolymerization was studied and the conditions for preparing monodisperse microspheres 370-1000 nm in diameter were determined.

Effect of the Surface Structure of Poly(styrene- co -acrolein) Microspheres and Its Modification by Protein on Electrosurface Properties

The electrophoretic mobility of poly(styrene-co-acrolein) microspheres was studied as a function of storage time. It was shown that pHIEP2.0 is retained but the abnormal dependence of electrophoretic mobility on NaCl concentration is replaced by classical dependence. When comparing chemisorption of bovine serum albumin (BSA) on the microsphere surface for various latex samples, the differences in the isotherm patterns was revealed; moreover, the prevalence of surface concentration of carboxyl groups over that of aldehyde groups resulted in a decrease in adsorption. After the modification of the microspheres by protein, the values of pHIEPfall within the range of 3.5–5.0 and their dependence on the amount of surface-bound protein passes the minimum. The results obtained are discussed in terms of the different arrangement patterns of protein molecules on the microsphere surface and the changes of BSA macromolecule conformations under the effect of a dispersion medium and as a result of chemical interaction with the polymer surface.

Sorption processes of styryl dyes dications with N-ammonioalkyl substituent of varying length on the surface of polystyrene submicroparticles

We have investigated the multilayer adsorption isotherms of styryl dyes (SDs) of pyridine series (dications) with active centers (COOH) of the surface of polystyrene colloidal particles in an aqueous solution, depending on the length of N-substituent and the particle diameter. A proposed model of sorption takes into account both the ion-exchange sorption mechanism (exchange of H+ ions to SD dications) and a phase equilibrium shift of SD solution to multilayer ionic condensate in the ionic diffusive layer near the electric charged surface of the particles if the concentration of the SD solution is high enough. Modeled sorption isotherms are in agreement with the experimental data.

Model of absorption of gaseous naphthalene by ordered layers of polymer submicroparticles with nanostructured shells

A new model describing the kinetics of absorption of naphthalene vapor from the atmosphere in three-ordered layers of polymer submicroparticles (400–450 nm) with both simple and porous (modified) shells and an impenetrable core was proposed. The experiment examined the layers of polymer particles made of poly(ethylene glycol dimethacrylatå) (PEGDM) containing various amounts of monolayers (2, 5, 10, and 20). The processing of the experiment using a physical model allowed one to obtain the rate constants of the naphthalene absorption by the polymer and the template pores of the particle shell. Based on these results, the effective thickness of the particle shell (about 15 nm) was estimated; the effective diffusion coefficient of the naphthalene in the polymer is D ≈ 0.2 nm2 s−1. The effective value of the energy barrier of the naphthalene sorption by the particle surface (about 4–5 kcal/mol) was calculated, which approximately corresponds to unsaturated hydrogen bond energy and may indicate the role of the adsorption layer of moisture on the particle surface. The efficiency of the model in describing the two-stage absorption of the analyte by the layers of submicroparticles with nanoporous shells was shown.