NEW POLYMER SYNTHESES .79. HYPERBRANCHED POLY(ESTER-AMIDE)S BASED ON 3-HYDROXYBENZOIC ACID AND 3,5-DIAMINOBENZOIC ACID

The reaction of 3-acetoxybenzoyl chloride (4) with N,N',O-tris(trimethylsilyl)-3,5-diaminobenzoic acid (5) proceeds by highly selective and almost quantitative acylation of both amino groups. The resulting 3,5-bis(3-acetoxybenzamido)benzoic acid (6a), or its silylated derivative 6b, was polycondensed in bulk. The silylated monomer yielded the higher molecular weights. The condensation of 3,5-diacetoxybenzoyl chlorides with diamines containing aliphatic protons yielded acetylated tetraphenols which served as ''star centers'' for polycondensations. The polycondensation of silylated 3,5-bis(3 -acetoxybenzamido)benzoic acid (6b) with these ''star centers'' yieled in turn hyperbranched star polymers. The feed ratio of monomers and ''star centers'' allows the control of the molecular weight. H-1 NMR spectroscopy of these hyperbranched star polymers was used to determine the average degree of polymerization (<(DB)over bar>) and the average degree of branching (<(DB)over bar>). H-1 and C-13 NMR spectroscopy also revealed that all polycondensations involve a significant extent of ester-amide interchange reactions.