Environmentally degradable aliphatic poly(ester-amide)s based on short, symmetrical and uniform bisamide-diol blocks, 1. Synthesis and interchange reaction

Aliphatic poly(ester-amide)s were prepared by polycondensation of N,N-1,4 butanediylbis(6-hydroxyhexanamide), dimethyl adipate, and 1,4-butanediol, using Ti(OBu)4 as a catalyst. For polymers with a bisamide monomer content below 25 mol-%, Mw between 20 000 and 50 000 were obtained after 10-12 h polymerization at temperatures of 170-190°C. Mw values decrease with increasing amide content. The symmetrical and uniform structure of the amide segments is retained in the polymer. Less than 5 mol-% of the symmetry of the amide segments is lost due to alcoholysis of the amide bonds in the first h of polymerization as found from NMR analysis. When the polymerizations were performed using adipic acid instead of dimethyl adipate a significant loss (up to 30 mol-%) of the symmetry of the amide segments occurs through acidolysis.