hyperbranched polyester soft segments (HB PU) with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylol)propionic acid of the fourth pseudo-generation (BoltornŽ H40) and hexamethylene (HDI) or isophorone diisocyanate (IPDI). The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young\u27s modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.Rad prikazuje sintezu i karakterizaciju poliuretana s mekanim segmentima od visoko razgranatoga poliestera (HB PU) s funkcionalnim karboksilnim skupinama s namjenom pripreme stabilnih disperzija HB PU. Za sintezu karboksiliranih HB PU upotrijebili smo visoko razgranati poliester na osnovi 2,2-bis(metilol)propionske kiseline četvrte pseudo-generacije (Boltorn H40) i heksametilen-diizocijanat (HDI) ili izoforon-diizocijanat (IPDI). Reaktivnost visoko razgranatog poliestra s HDI-om bila je niža od očekivane, vjerojatno zbog postojećih manje reaktivnih hidroksilnih skupina u linearnim jedinicama. Reakcijske smjese gelirale su kod množinskog omjera rNCO/OH = 1:2 i 1:4. HB PU sintetizirali smo iz djelimično preostaloga visoko razgranatoga poliestera s nižom -OH funkcionalnosti. Karboksilne skupine smo u lanac HB PU uveli s esterifikacijom neizreagiranih hidroksilnih skupina s anhidridom cis-1,2-cikloheksandikarboksilne kiseline. Vodene disperzije HB PU bile su stabilne najmanje dva mjeseca, filmovi su bili krhki. Ispitivanja na vučnu čvrstoću i na Youngov modul elastičnosti su pokazali da su se iznosi kod smjesa linearnoga i HB PU s povećavajućim udjelom HB PU se smanjivali, dok je naprezanje na rastezanje do loma ostalo nepromijenjeno, što smo objasnili s manje gustim slaganjem lanaca zbog više otvorenih drvenastih visoko razgranatih struktura
