Star-shaped and hyperbranched polyesters

In contrast to a-a/b-b type monomers, the a-b monomers(e.g.hydroxy- or amino carboxylic acids) possess a much greater synthetic potential. Using 3- or 4-hydroxybenzoic acid and 4-hydroxyphenylpropionic acid (phloretic acid) starshaped polyesters with controlled molecular weight were prepared. Analogously, starshaped liquid-crystalline copolyesters were synthesized, and the influence of star-centers on the stability of the nematic phase was studied. Three polycondensation methods were elaborated and compared for the synthesis of hyperbranched homo- and copolyesters. Both the degree of branching and the nature of the endgroups were varied and their influence on the solubility, crystallinity and melt rheology was investigated. Furthermore, A-B-A triblock co-polymers with hyperbranched A-blocks, and hyperbranched poly(ester-amide)s were synthesized and characterized.