Synthesis, characterization, and biodegradability of novel regular-network polyester-amines based on 1,1,1-triethanolamine

Regular-network polyester-amines were prepared from 1,1,1-triethanolamine (Y-N) and various dicarboxylic acids [HOOC--(CH2)(n=2)-COOH, n = 6-14]. A prepolymer prepared by melt polycondensation was cast from dimethylformamide solution and postpolymerized at 220 degreesC in a nitrogen flow for various periods of time to form a network. The resultant films were transparent, flexible, and insoluble in organic solvents. The network polyester-amines obtained were characterized by infrared absorption spectra, wide-angle X-ray diffraction analysis, density, DSC, and thermomechanical analysis. The biodegradation experiments for the network polyester-amine films were carried out in enzymatic solution with Rhizopus delemar or Pseudomonas cepacia lipase and in an activated sludge. The degree and rate of biodegradation were estimated by the weight loss of the films. After incubation in Rhizopus delemar lipase solution for 24 h, weight loss was hardly observed for Y(N)6-7, whereas it increased greatly for Y(N)8-13 (13-51 g/m(2)), and then it decreased rapidly for Y(N)14. The methylene-chain dependence of degradation was essentially the same as in the case of network polyesters from glycerol and various aliphatic dicarboxylic acids reported previously. Psedomonas cepacia lipases also degraded Y(N)n films, but the rate of degradation was much slower than Rhizopus delemar lipase. In the exposure to activated sludge for 30 days, the network polyester films with medium methylene-chain lengths (Y(N)7-11) showed the lager weight loss, as in the case of the enzymatic degradation, whereas the rate of biodegradation was much slower than that of the enzymatic degradation with Rhizopus delemar lipase. The effect of the protonation of the film with hydrochloric acid on the enzymatic degradation was also examined. (C) 2001 John Wiley & Sons, Inc.