Polymer, Vol.50, No.15, 3431-3439, 2009
Synthesis and characterization of A(2) + B-3-type hyperbranched aromatic polyesters with phenolic end groups
Hyperbranched (hb) aromatic polyesters with phenolic end groups were synthesized according to the A(2) + B-3 approach both, by solution polymerization and by melt (bulk) polymerization with different monomer ratios (A(2):B-3). The hb polyesters produced from solution polymerization exhibited higher yields, molar masses and glass transition temperature (T-g) compared to the products prepared in the melt. The resulting hb aromatic polyesters from the A(2) + B-3 approach were also compared with their properties to lib aromatic polymers produced from the well known AB(2) monomer 3,5-bis-(triniethylsiloxy)benzoyl chloride. Both types of hb aromatic polyesters possess high T-g, high thermal stability and good solubility in common organic solvents. A typical melt viscosity behavior with shear thinning effect was also observed for both. Thus similar polymer properties compared to melt-condensed products were obtained with the A(2) + B-3 approach by solution polycondensation possessing the advantage of easy monomer availability and much milder polymerization conditions (at room temperature in solution) compared to the AB(2) approach. (C) 2009 Elsevier Ltd. All rights reserved.