SYNTHESIS OF NOVEL BIODEGRADABLE POLY(ESTER-ANHYDRIDE)S

Poly(epsilon-caprolactone)s containing one and variable numbers of anh ydride functions along the polymer backbone were synthesized and chara cterized. The inclusion of a single anhydride unit involved the coupli ng of monofunctional carboxylic acid-terminated prepolymers using diph enyl chlorophosphate. The prepolymers were produced using standnous oc toate as catalyst and ethanol as the initiator, yielding monofunctiona l hydroxyl-terminated intermediates which were reacted with succinic a nhydride in the presence of 1-methylimidazole. Diphenyl chlorophosphat e was then added to a solution of the carboxylic acid-terminated prepo lymer and triethylamine in 1,2-dichloroethane, and the reaction was ca rried out for 5 hours at room temperature to yield a polyester contain ing a single anhydride unit. The synthesis of polymers containing a va riable number of anhydride linkages per chain was carried out in a sim ilar manner using difunctional carboxylic acid-terminated prepolymers as chain-extending segments, and monofunctional carboxylic acid-termin ated prepolymers as end-capping units. The difunctional hydroxyl-termi nated poly(epsilon-caprolactone) prepolymers were produced using dieth ylene glycol as the initiator, and then reacted with succinic anhydrid e to form difunctional carboxylic acid-terminated prepolymers.