SYNTHESIS, CHARACTERIZATION, AND DEGRADATION OF BLOCK POLYESTERAMIDES CONTAINING POLY(L-LACTIDE) SEGMENTS

Random multiblock polyesteramides (PEAs) having polyester (PE) content of 20-50 wt % have been prepared by low-temperature polycondensation using sebacoyl chloride, 1,6-diaminohexane, and telechelic oligomers of L-lactide with M(n) = 600-1500. The PEAs were characterized by IR and H-1-NMR spectroscopy, wide-angle X-ray diffraction, and thermal analysis. Only the polyamide segments are able to crystallize, and the crystallinity depends on the composition and architecture of the PEAs. From viscosity and IR measurements it was established that the chain degradation of PEA powders or films suspended in buffer solutions occurs by hydrolysis of the ester linkages. The degradation rate is influenced by pH, PE content, and, to a lesser extent, by crystallinity.