Kinetic Analysis of Two Hyperbranched A2 + B3 Polycondensation Reactions by NMR Spectroscopy

Abstract

The kinetics of the polycondensation of A2 and B3 monomers leading to hyperbranched polyesters was studied by NMR spectroscopy and compared with theoretical predictions. Combinations of two different A2 monomers, the aromatic terephthaloyl chloride (TCl, A2) and the aliphatic adipic acid (AA, A2), respectively, with 1,1,1-tris(4-trimethylsiloxyphenyl)ethane (TMS−THPE, B3) and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE, B3), respectively, were studied in different molar ratios of the monomers. On the basis of a complete 1H and 13C NMR signal assignment for the structural units of the two resulting hyperbranched polymers their relative concentration as a function of conversion was determined. In the case of TCl/TMS−THPE, the degree of branching just before gelation increased with increasing A2 content. A further increase of DB could be obtained by sequential addition of the A2 + B3 monomer mixture. Since the kinetic data for that system did not describe the development of structural units expected for equal an...