Synthesis, Characterization, and Investigation of Thermosensitive Star- Shaped Poly(2isopropyl-2-oxazolines) Based on Carbosilane Dendrimers

Star-shaped poly(2-isopropyl-2-oxazolines) with dramatically hydrophobic dendrimer core are synthesized using carbosilane dendrimers of first to third generations as macroinitiators. It is observed that half of the initiator functional groups are incorporated in polymerization process. The polymerization degree of polyoxazoline arms is about 25. Strong arm folding results in small molecule dimensions in both aqueous and organic solutions. Thermosensitive properties are studied for second generation-based star solution with the concentration of 0.00095 g cm(-3). Model linear poly(2-isopropyl-2-oxazolines) are investigated for comparison. Carbosilane dendrimer core interaction leads to the formation of different types of aggregates at low temperatures. The temperatures of the beginning (T-1 = 42-43 degrees C) and finishing (T-2 = 50 degrees C) of phase separation are determined. It is shown that macromolecule compactization and aggregation take place even far from the phase transition interval and alternately prevail on heating.