Acid chloride‐functionalized hyperbranched polyester for facile and quantitative chain‐end modification: One‐pot synthesis and structure characterization

Carboxylic acid chloride end‐functionalized all‐aromatic hyperbranched polyesters were prepared from the bulk polycondensation of the AB 2 monomer 5‐(trimethylsiloxy)isophthaloyl dichloride. The acid chloride end functionality of the hyperbranched polyester was modified in situ with methanol and yielded methyl ester ends in a one‐pot process. Chain‐end functionalization and esterification were quantitative according to both potentiometric titration and 1 H NMR analysis. The signals of 1 H and 13 C NMR spectra of the esterified hyperbranched polyester were fully assigned from model compounds of the focal, linear, dendritic, and terminal units. The degree of branching and molecular weight averages measured by 1 H and 13 C NMR spectroscopy and multidetector size exclusion chromatography increased systematically with increasing polymerization temperatures between 80 and 200 °C.