Abstract
Solution behaviour of new star poly(ether urethane)s based on erythromycin propionate core at different concentrations and temperatures in N,N-dimethyl formamide was studied by viscometry. The impact of the star polyurethanes chemical structures and molecular weights, solvent, temperature and of the interactions from the system on the viscosities and dimensions of the polymer chain in dilute solution was investigated. The model of Qian and Rudin was used to predict the hydrodynamic properties of the solvated star polyurethanes in solution. The variations of the hydrodynamic parameters expressed by intrinsic viscosity, expansion factor, second virial coefficient, unperturbed dimension parameters, hydrodynamic volume as well as of the dimensions of the polymer chain namely radius of gyration and density were studied, justifying that the conformational changes from the system occur as result of the interactions generated by hard segments, polyether arm and the solvent. MDI star polyurethanes evidence less expanded conformation in comparison with TDI star polyurethanes as attested by GPC results, intrinsic viscosity and parameter for unperturbed dimensions. The solubility parameter is found higher for TDI star polyurethanes and higher content of urethane groups.
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