Alexander Yu. Bilibin

Dilational surface viscoelasticity of polymer solutions

A review of recent results on the dilational surface viscoelastic properties of aqueous solutions of non-ionic polymers is given. In the frequency range from 0.001 up to 1000 Hz the methods of transverse and longitudinal surface waves and the oscillating barrier method were applied. Viscoelastic behavior of adsorbed polymer films significantly differs from the behavior of films formed by only conventional surfactants of low molecular weight. For example, the dynamic surface elasticity of the former systems is low and almost constant in a broad concentration range. One can observe the increase of the surface elasticity only at extremely low concentrations and/or in the range of semi-dilute solutions. If the surface stress relaxation in conventional surfactant solutions is usually determined by the diffusional exchange between the surface layer and the bulk phase, the relaxation processes in the polymer systems proceed mainly inside the surface layer. Possible mechanism of the latter relaxation is discussed.

Novel surfactant-selective membrane electrode based on polyelectrolyte-surfactant complex.

Novel class of active ionophores for surfactant selective electrodes is proposed. PVC membrane doped with polyelectrolyte-surfactant stoichiometric complex is used for ion-selective electrode construction responsive to cetyltrimethyl ammonium bromide and related surfactants. New ionophore is quite stable and completely insoluble in aqueous media in wide range of pH. The electrode displays nearly Nernstian slope in CTAB concentration range 10(-6)-10(-3)M. Polyelectrolyte platform allows to design wide range of different ionophores responsive to cationic organic substances.

Effect of preparation conditions on properties of polylactide and polystyrene and their composite microparticles made by emulsion solvent evaporation method

In this study, polylactide and polystyrene microparticles have been prepared by emulsion solvent evaporation method. Effects of polymer nature, stirring speed, emulsifier, and concentration of the components on the size, size distribution and morphology of polymeric microparticles have been investigated. 11-Acryloyl-aminoundecanoic acid and its polymer poly(11-acryloyl-aminoundecanoic acid) were tested for comparison with traditional emulsifiers such as sodium dodecylsulfate. Interfacial tension measurement was applied to compare these emulsifiers. Dynamic light scattering and scanning electron microscopy were used to analyze microparticles. Polylactide/polystyrene composite microparticles have been prepared as well; their surface morphology has been studied.

Polymer-CNT nanocomposites based on polymerizable surfactants

Polymer –CNT composites were prepared using surface active monomers for stabilization of CNT dispersion followed by monomer precipitation polymerization. Composites obtained possess fine lamellar structure revealed by SEM and SAXD. Composites are completely soluble in some organic solvents and form stable CNT dispersions.

Correlation of the thermal properties of main‐chain liquid crystalline polymers with the symmetry and anisometry of their mesogens

Several series of liquid crystalline poly[aroyl-bis(oxyarylates)] with oligomethylene (n = 6 and 10) and oligooxyethylene (n = 2; 3; 4 and -) spacers were synthesized. The structure of their mesogenic groups was varied by replacement of central or terminal units by those with reduced symmetry. The polymers were invetigated by methods, such as differential scanning calorimetry, polarizing optical microscopy and in some selected cases by X-ray diffraction methods using synchrotron radiation. An absence of transesterification during measurements at elevated temperatures was proved by 13 C NMR spectroscopy. The formation of smectic melts was demonstrated for all the polymers with high symmetry of the mesogenic group. A lower symmetry leads to a decrease of crystallinity of the polymers and to the appearance of a nematic phase in their melts. Comparative analyses of their thermal properties were made in order to determine the contribution of each single unit of the mesogenic groups on the thermal properties of the polymers.

Molecular and conformational properties of comb-like polymers with ionically bound side chains studied in organic solvent

ABSTRACT Conformational and dynamo-optical properties of a homologous series of poly(cetyltrimethylammonium 2-acrylamido-2-methylpropane sulfonates) with molecular masses ranging from 80 to 700 kDa were studied in chloroform solutions by viscometry, dynamic light scattering, sedimentation, and flow birefringence. The Mark–Kuhn–Houwink Equations for this polymer in chloroform were obtained; the values of hydrodynamic diameter and the Kuhn segment length as well as the value of intrinsic anisotropy of polarizability of the monomer unit were defined.

Porous structure formation via phase separation of two polymers Blends of aromatic polyoxalates and poly(lactic acid)

Abstract A new method of porous polymer structure formation by means of phase separation of two polymers with different degradation rates is proposed. Aromatic polyesters of oxalic acid as fast degradable polymers were synthesized and their degradation properties under alkaline conditions were studied. Heterogeneous mixtures of poly(phenolphthalein oxalate) with poly(lactic acid) were prepared by solution phase separation and co-precipitation, and porous poly(lactic acid) samples were produced by polyoxalate leaching due to its fast degradation.