New polymer syntheses, 91. Hyperbranched poly(ester-amide)s derived from 3,5-dihydroxybenzoic acid and 3,5-diaminobenzoic acid

✍ Scribed by Hans R. Kricheldorf; Oliver Bolender; Thomas Stukenbrock

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 618 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021980902

✦ Synopsis

Abstract

A new pentafunctional monomer (3a) was prepared by acylation of silylated 3,5‐diaminobenzoic acid (DABA) with 3,5‐bisacetoxybenzoyl chloride. The polycondensation of this monomer or its trimethylsilyl ester yielded a hyperbranched poly(ester‐amide) having a nearly alternating sequence of one DABA and two 3,5‐dihydroxybenzoic acid (DHBA) units. However, due to ester‐amide interchange reactions, ca. 15–25% of the DABA units lose their role as branching units. When 3,5‐bisacetoxybenzoic acid and 3,5‐bisacetamidobenzoic acid were copolycondensed in a 2:1 ratio, the resulting polymer and endgroup structures were different. Furthermore, hyperbranched copoly(ester‐amide)s with a variable DHBA/DABA ratio from 10:0 down to 3:7 were prepared. The glass transition temperature (T~g~) increased by approx. 90°C (up to 250°C) at higher molar fractions of DABA. Furthermore, monomer 3a was copolycondensed with 3‐acetoxybenzoic acid or its trimethylsilyl ester. The resulting copoly(ester‐amide)s were again amorphous, showing a continuous decrease of the T~g~ down to the value of the poly(3‐hydroxybenzoic acid) (poly(3‐HBA)) around 136–140°C.