Abstract
ABSTRACT Two new multifunctional monomers (1a, 2a) were prepared by acylation of silylated 4-aminobenzoic acid or 3,5-bisaminobenzoic acid with trisacetyl gallic acid chloride. All attempts to prepare soluble hyperbranched homopolyesters from the monomers 1a or 2a failed because of crosslinking. In contrast, copolycondensations of the “branching monomers” 1a or 2a with the trimethylsilyl esters of acetylated vanillic acid or phloretic acid yielded soluble randomly branched copoly(ester-amide)s at a maximum reaction temperature of 220°C or 230°C. As evidenced by 1H NMR spectroscopy, all these copoly(ester-amide)s possess acetamide endgroups in addition to the acetate endgroups due to ester-amide interchange reactions. All copoly(ester-amide)s are amorphous materials with glass-transition temperatures (Tg's) between 170 and 230°C. The Tg's increase with the molar fraction of amide groups.
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