Marina M. Dudkina

Thermoresponsive Star-Shaped Poly(2-isopropyl-2-oxazoline) in Aqueous Solution

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazoline) with t-butylcalix[8]arene core was studied by light scattering methods in aqueous solution. The sample under investigation has Mw = 19600 g mol−1 and PDI of arms 1.41. The bimodal distribution of scattering objects was observed even at room temperature. The redistribution of these two kinds of particles takes place at T = 27°–36°C. At higher temperatures the growth of large particles, disappearance of the small component, and appearance-disappearance of “middle-size” aggregates were observed. Only the large particles with the hydrodynamic radius 95 nm exist in proximity to LCST (37.5°C).

Deuterium Isotope Effect on Solution Behavior of Thermoresponsive Star-Shaped Poly(2-isopropyl-2-oxazoline)

Thermosensitive star-shaped poly(2-isopropyl-2-oxazoline) (molar mass M≈21000 g mol−1) in D2O solution was studied by the static and dynamic light scattering methods. The behavior of the polymer investigated in deuterated water is similar qualitatively to that observed previously in undeuterated water. At the same time, the considerable quantitative changes of polymer behavior in D2O were seen. Deuterium substitution of solvent affects the phase transition temperature by decreasing its value by 1°C. The temperature interval of phase transition in D2O solution expands (by about 1°C) in comparison with that in H2O solution.

Synthesis of Star-Shaped Polymers Based on 2-ALKYL-2-Oxazoline with a Calix[8]Arene Central Core and the Study of Their Heat-Sensitive Properties

This work describes the synthesis of thermosensitive eight-point star-shaped polymers with a central core comprised of residual octa-ester-tert-butylcalix[8]arene with oligo-2-ethyl-2-oxazoline-block-2-isopropyl-2-oxazoline rays. It is found that, despite the presence of two blocks with substantially different temperatures of the coil – globule transition, block copolymers exhibit only one lower critical solution temperature (LCST), and the phase transition is observed at a temperature close to the transition temperature of the homopolymer with a lower LCST. For the first time it is found that, upon incubating for some time in an aqueous solution above the LCST, star polymers with temperature-sensitive polyoxazoline rays self-assemble to form nanofibers and structures with more complex morphology.

Role of the deuterium isotope in the formation of the behavior of thermosensitive poly(2-isopropyl-2-oxazoline)

Thermosensitive star-shaped poly(2-isopropyl-2-oxazoline) is studied via light scattering in D2O solutions in a ten-fold concentration range at the temperatures from 21 to 60°С. The data are compared to the results of investigations on this polymer in Н2O at close concentration values. A qualitative similarity in behavior of the polymer in the compared solvents is established; the changes that occur after the change from Н2O to D2O are quantitative. After changing to the deuterated solvent, the initial temperature of phase separation decreases by 0.5–1.0°С. The lower the solution concentration, the greater the width of the phase-separation interval.

Supramolecular polymeric complexes of calix[8]arenes

Formation of ionic complexes of calix[8]arenes with polymers of various basicities was studied, and previously unknown ternary polymeric complexes of calix[8]arenes of the ion-ion (polymer-calixarene-uranyl ion) and ion-hydrophilic molecule-hydrophobic molecule (polymer-calixarene-fullerene) types were prepared.

Influence of the Chemical Structure of 4-Hydroxybenzylidenealkanones on Nonlinear Optical Properties of Their Complexes with Poly-1,10-Decamethyleneacetamidine

The influence exerted by the length exerted by the conjugation chain in 4-hydroxybenzylidenealkanones on the generation of the third harmonic by complexes of these chromophores with aliphatic polyamidine was studied.