SYNTHESIS AND BIODEGRADATION OF COPOLYESTERETHER OF COPOLY(SUCCINIC ANHYDRIDE ETHYLENE-OXIDE) WITH TRIBLOCK COPOLYMER OF Y(OXYETHYLENE)-POLY(OXYPROPYLENE)POLY(OXYETHYLENE)

The thermal properties and biodegradability of the block copolyesteret hers with copoly[succinic anhydride (SA)/ethylene oxide (EO)], synthes ized by ring-opening copolymerization as a hard segment and the triblo ck copolyethers of ethylene)-poly(oxypropylene)-poly(oxyethylene)(PN) as a soft segment, were studied. The block copolyesterethers synthesiz ed from higher than 8000 number-average molecular weight (M-n) of copo ly(SA/EO)s showed a microphase separation structure as determined by t he thermal properties [melting point (T-m) and glass transition (T-g)] , at any polymer composition [EO/propylene oxide (PO)] or the determin ation of M-n of PN. A decrease in the M-n of copoly(SA/EO) or an incre ase in PO content in PN resulted in depression of heats of fusion (Del ta H) of these block copolyesterethers. The enzymatic degradation of t he block copolyesterethers by the lipase from Rhizopus arrhizus showed a substantial increase with a decrease in their Delta H, whereas it w as depressed with an increase in the M-n of polyoxyethylene or polyoxy propylene segment in the block copolyesterethers. The block copolyeste rethers were degraded by microorganisms in activated sludge. The biode gradability of the block copolyesterethers showed a pronounced drop, w ith an increase in the polyoxyethylene chain length or polyoxypropylen e content in PN. The polycondensation was also conducted without a cat alyst at 190 degrees C, similarly, to the reaction catalyzed with Ti[O CH(CH3)(2)](4) at 170 degrees C. The effect of the residual titanium o n the biodegradability of the block copolyesterethers was negligible. (C) 1998 John Wiley & Sons, Inc.