DEGRADABLE POLY(ESTER AMIDE)S BASED ON L-TARTARIC ACID

A series of poly(ester amide)s with ester/amide group ratios ranging f rom 1/99 to 1/4 were obtained using 1,6-hexanediamine, 1,6-hexanediol and 2,3-di-O-methoxy-L-tartaric and succinic acids as building blocks. The ester linkages were introduced in pairs using as comonomer the di acid resulting from the esterification of 1,6-hexanediol with 2 mol of succinic anhydride. Polycondensastion reactions were carried out in s olution at room temperature with the diamine activated as the N,N'-bis (trimethylsilyl) derivative and the two diacids as bis(pentachlorophen yl) esters. The prepared poly(ester amide)s have number average molecu lar weights in the range 10 000-40 000, display optical activity and a re soluble in chloroform. These copolymers were found to be highly cry stalline with melting points above 200 degrees C and mechanical moduli comparable to those reported for the parent polyamide poly(hexamethyl ene-di-O-methyI-L-tartaramide). They were degraded by aqueous buffer o f pH 7.4 at a rate that increased with the content of the copolymer in succinic acid units. H-1 n.m.r. evidenced that no reactions other tha n those entailing the hydrolysis of the main chain ester bonds appear to take place at polymer degradation. (C) 1997 Elsevier Science Ltd.