T. V. Panova

The effect of the charge of astramol™ poly(propylene imine) dendrimers on interaction with polyanionic gels

The effect of the charge of Astramol™ poly(propylene imine) dendrimers of the third and fourth generations on activated sorption of dendrimer molecules by weakly crosslinked polyanionic networks was studied. It was shown that the formed interpolyelectrolyte complex was markedly enriched in the weakly charged dendrimer as the degree of dendrimer neutralization decreased. As was found, depending on the conditions of sorption of dendrimers by oppositely charged networks, this process leads to the formation of either macroscopically heterogeneous “shell-core” structures or microheterogeneous composites with uniform distribution of micrometer-sized clusters of dendrimer molecules in the gel matrix. The structure of such systems separated at the microphase level was studied by the laser scattering technique. Their high ordering was established, and the reasons behind the formation of various alternative heterophase systems were discussed.

Behavior of multiwalled carbon nanotubes functionalized with sulfo groups in aqueous salt solutions

The functionalization of multiwalled carbon nanotubes (MWCNTs) with sulfanilic acid through the diazotization reaction, which yielded the covalent bonding of sulfo groups to the nanotube surfaces, was performed. Stable aqueous nanotube dispersions were obtained. The sizes of functionalized nanotubes in aqueous salt and salt-free solutions and their hydrodynamic characteristics were measured by dynamic light scattering. The data were compared with the data of scanning electron microscopy.

Interaction of ampholyte dendrimers with network polycations and polyanions

The interaction of polyampholyte propylenimine dendrimers of five generations containing peripheral carboxyl and inner tertiary amino groups with lightly crosslinked highly swelling polyelectrolyte gels has been studied. It has been shown that the polyampholyte dendrimers of all five generations are efficiently sorbed by a polyanion sulfur-containing hydrogel (below the isoelectric point) and a polyamine hydrogel (above the isoelectric point) to give rise to interpolyelectrolyte complexes. The composition of interpolyelectrolyte complexes and the equilibrium concentration of the dendrimer in the surrounding solution are appreciably affected by the pH of the medium. Amount of zwitterion pairs in a dendrimer molecule significantly influence the formation of interpolymer salt bonds. The polyampholyte dendrimer can pass from an anionic hydrogel to a cationic one upon a small change in pH near the isoelectric point.

Different types of phase separation in polycomplex gels based on a lightly crosslinked polyanion and poly(propylene imine) dendrimer

Various types of structural organization of polycomplex gels based on a lightly crosslinked anionic sulfonate gel and Astramol poly(propyleneimine) dendrimer of the fourth generation were studied. It was shown that along with macroscopic two-phase structure of the core-shell type, which is formed in the process of activated dendrimer sorption by anionic gel, a microheterogeneous composite with polycomplex phase particles of micron dimensions uniformly distributed in the network matrix is also formed. Such microheterogeneous composites are formed as a result of dendrimer molecule redistribution in a lightly crosslinked anionic gel during dendrimer charge change. The parameters of the microheterogeneous structure of polycomplex gel forms were evaluated by the laser scattering technique. It was found that the size of dendrimer aggregates depends on the value of the network degree of swelling.