Hyperbranched Aromatic Polyesters with Carboxylic Acid Terminal Groups

Melt condensation of 6-acetoxyisophtalic acid (1) and 5-(2-hydroxyethoxy)isophthalic acid (4) yielded hyperbranched aromatic polyesters with carboxylic acid terminal groups. The polymer of 1 has a T g of 289°C and thus required melt acidolysis polymerization temperatures of 240-260°C to obtain M w s in the 20000 to 80000 range. The polyesters based on 4, with a lower T g , was obtained at around 190°C standard polycondensation techniques. NMR studies revealed the degree of branching to be about 50%, similar to what has been observed in other hyperbranched polyester systems