H. Kricheldorf, Olaf Stoeber, D. Lübbers
Nov 1, 1995
Citations
0
Influential Citations
20
Citations
Journal
Macromolecular Chemistry and Physics
Abstract
Randomly branched (hyperbranched) poly(3-hydroxybenzoate), poly(3-Hybe), was prepared by polycondensation of silylated 3-acetoxybenzoic acid with either silylated 3,5-diacetoxybenzoic acid or bis(trimethylsilyl) 5-acetoxyisophthalate. The number of branching points was varied by changing the feed ratio of difunctional and trifunctional monomers. 1 H NMR and 13 C NMR spectroscopy proved the nearly random incorporation of the trifunctional branching units. Cocondensations with small amounts of acetylated bisphenol-P allowed one to control the degree of polymerization (DP) and to determine the DP by 1 H NMR spectroscopy. However, analogous copolycondensations with silylated 2-(4-tert-butylphenoxy)terephthalic acid failed. According to GPC measurements, weight-average molecular weights above 10 5 were obtained. DSC measurements revealed that the glass transition temperatures (T g 's) vary largely with the degree of branching (DB) and with the nature of the end-groups. In the case of phenolic OH and acetate end-groups, the relationship T g vs. number of branching points passes through a minimum.