Karakterizacija komercijalnih hiperrazgranatih poliestara

In this paper, properties of the commercially available Boltorn® 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® 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® 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 β-alanine to obtain hyperbranched samples soluble in water. That was fully accomplished only for the Boltorn® 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.U ovom radu prikazani su rezultati ispitivanja tri uzorka Boltorn® hidroksi-funkcionalnih hiperrazgranatih alifatskih poliestara druge, treće i četvrte pseudo generacije, kao i frakcija uzoraka treće i četvrte pseudo generacije. Primenom GPC analize pokazano je da sa povećanjem broja pseudo generacije dolazi do rasta molarne mase ali i polidisperznosti ovih uzoraka. Vrednosti graničnog viskozitetnog broja i hidrodinamičkog prečnika ispitivanih poliestara, određenih u N-metil-2-pirolidonu kao rastvaraču, rastu sa povećanjem broja pseudo generacije, dok kod frakcija ove vrednosti opadaju od prve do treće frakcije. Na osnovu termogravimetrijskih rezultata konstantovano je da termička stabilnost ovih uzoraka raste sa povećanjem broja pseudo- generacije. Modifikovanjem krajnjih hidroksilnih grupa Boltorn® hiperrazgranatog poliestra druge pseudo generacije β-alaninom dobijen je uzorak rastvoran u vodi, dok se uzorak treće pseudo generacije, takođe modifikovan β-alaninom, rastvorio u vodi nakon dodavanja male količine NaOH