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 M_w = 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).

Hyperbranched polycarbosilanes are investigated by the methods of molecular hydrodynamics and optics. Dependences of the hydrodynamic and conformational properties of these polymers on their molecular mass, the length of linear chains between branching points, and the chemical structure of end groups are analyzed. The hydrodynamic behavior of hyperbranched polycarbosilanes is explained by the fact that the dimensions of their macromolecules are compact and their shape is close to spherical. The convolution of chains between branching points becomes more pronounced with an increase in their length and a decrease in the molecular mass of the polymer. When end fluorinated groups are incorporated into the hyperbranched polycarbosilane, in thermodynamically good solvents and θ solvents, hydrodynamic characteristics change apparently owing to a change in the density of macromolecules in solution. In a poor solvent, the compaction of fluorinated macromolecules and a reduction in their shape asymmetry are observed. At a fixed branching degree, the hydrodynamic properties of hyperbranched polymers depend on the structural regularity of their macromolecules: In terms of hydrodynamic properties, the hyperbranched polycarbosilane with a degree of branching of 1 and a random distribution of branching points within the volume of a macro-molecule is appreciably different from a dendrimer of the same chemical nature and is close to polycarbosilanes with a degree of branching of 0.5.

Four-arm star-shaped poly(2-isopropyl-2-oxazolines) (PiPrOx₄) are synthesized by cationic polymerization on t-butylcalix[4]arene macroinitiator. The obtained samples differ by polymerization degree of arms N_PiPrOx = 9 and 25 and are characterized in chloroform. The behavior in aqueous solutions is studied by light scattering methods and compared with the results of investigation of eight-arm star with similar structure. Three types of particles are observed in solution of short-arm PiPrOx₄ at room temperature, whereas only two particle types are present in long-arm star solution. Arm shortening leads to widening of the phase transition interval. The arm number decreasing reduces the phase transition temperature by 1°C.