Conversion dependence of the structural units and the degree of branching of a hyperbranched polyester based on 4,4-bis-(4 '-hydroxyphenyl)pentanoic acid determined by NMR spectroscopy

The hyperbranched polyester based on 4,4-bis-(4-hydroxyphenyl)pentanoic aci d was synthesized with different DP's. A complete H-1 and C-13 NMR assignme nt of the oligomers was carried out. Six different structural units were qu antified by NMR analysis. The conversion dependence of the content of these structural units and of the degree of branching DB follows the theoretical ly derived equations. Furthermore, six different diads were quantified by C -13 NMR spectroscopy. The conversion dependence of the diads was calculated and again the measured data agree well with the theory. The good fit betwe en theoretical and measured data proves, that the polycondensation of the 4 ,4-bis-(4'-hydroxyphenyl)pentanoic acid follows a random growth of the diff erent units with equal reaction rates of all reaction steps. Finally, spin- lattice relaxation times (T-1C) and nuclear Overhauser enhancements (NOE) w ere determined and discussed.