Structural and hydrodynamic characteristics of polystyrene synthesized in the presence of conjugated dinitrones

A series of branched high-molecular-weight alkoxyamines (HAAs) based on polystyrene of different molecular weight were synthesized using nitroxide radicals generated in situ in the presence of conjugated dinitrones (N,N-dimethylglyoxaldinitrone, N,N-di-tert-butylgly-oxaldinitrone, and N,N-diphenylglyoxaldinitrone). Structural features of the products obtained were studied by MALDI-TOF mass spectrometry. Modification of the synthesized HAAs in the presence of azobisisobutyronitrile, carbon tetrabromide, dodecyl mercaptane, 4,5,5-trimethyl-2,2-diethyl-2,5-dihydroimidazole-1-oxyl, and 3,5-di-tert-butylbenzoquinone, as well as thermolysis of the HAAs in the presence of atmospheric oxygen showed that the nitroxide fragments are located within the polymer chain irrespective of the initial structure of the conjugated dinitrone. The molecular weight characteristics and conformational properties of the nitroxide-containing linear macromolecules and polymers were studied by static and dynamic light scattering and by viscometry. In most cases, the calculated values of the ρ-parameter (R_g/R_h) and the Zimm viscosity factor of the branched polystyrene samples synthesized using conjugated dinitrones are lower than those of linear analogues.