CHARACTERIZATION OF THE COMMERCIAL HYPERBRANCHED POLYESTERS

Abstract

In this paper, properties of the commercially available Boltorn (R) hydroxy-functional aliphatic hyperbranched polyesters of the second, third and fourth pseudo generation, were investigated. Additionally, samples of the third and fourth pseudo generation were fractionated using the precipitation fractionation method to obtain three fractions of each sample, which were also investigated in this paper. According to the results obtained by GPC analysis, molar mass and polydispersity of the investigated Boltorn (R) hyperbranched polyesters increased with increase of the pseudo generation number. Value of the limiting viscosity number of the investigated samples, determined using the viscosity measurements of dilute solutions of these polymers in N-methyl-2-pyrrolidone, increased with the increase of the pseudo generation number. On the other hand, the value of the limiting viscosity number of the fractions decreased from the first up to the third fraction. The same trend was also observed for the values of the hydrodynamic diameter of parent samples and their fractions, determined by dynamic light scattering using N-methyl-2-pyrrolidone as solvent. The thermal properties of the investigated Boltorn (R) hyperbranched polyesters were determined by thermogravimetry in nitrogen atmosphere and it has been shown that thermal stability of these samples increased with increase of the pseudo generation number. End hydroxyl groups of the second and third pseudo generation samples were modified with beta-alanine to obtain hyperbranched samples soluble in water. That was fully accomplished only for the Boltorn (R) hyperbranched polyester of the second pseudo generation. On the other hand, it was possible to dissolve the modified sample of the third pseudo generation in water only after adding a small amount of the NaOH.