Investigation into the solution properties of hyperbranched polymer

The solution properties of hydroxyl terminated hyperbranched aliphatic polyesters and their acetyl derivatives have been studied by measuring viscosity parameters. The polarity of terminated groups of molecules is the most important factor affecting their properties. The intrinsic viscosity [η] cannot reflect the real monomolecular hydrodynamic volume of hydroxyl group-terminated hyperbranched polymer due to the strong intermolecular forces which lead to the formation of stable clusters. The intermolecular association constant K_M depends not only on molecular weight, but also on the polarity of end-groups. However, the dynamic contact concentration C_s can be determined accurately from reduced viscosity versus concentration plots. The reason why the intrinsic viscosity does not change linearly with the generation of the hyperbranched aliphatic polyesters is explained using 'free-draining' and 'non-draining' models.