Add time:08/30/2019         Source:sciencedirect.com

A series of poly(ester amide)s with ester/amide group ratios ranging from 199 to 14 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 diacid resulting from the esterification of 1,6-hexanediol with 2 mol of succinic anhydride. Polycondensastion reactions were carried out in solution at room temperature with the diamine activated as the N,N′-bis(trimethylsilyl) derivative and the two diacids as bis(pentachlorophenyl) esters. The prepared poly(ester amide)s have number average molecular weights in the range 10 000–40 000, display optical activity and are soluble in chloroform. These copolymers were found to be highly crystalline with melting points above 200°C and mechanical moduli comparable to those reported for the parent polyamide poly(hexamethylene-di-O-methyl-l-tartaramide). They were degraded by aqueous buffer of pH 7.4 at a rate that increased with the content of the copolymer in succinic acid units. 1H n.m.r. evidenced that no reactions other than those entailing the hydrolysis of the main chain ester bonds appear to take place at polymer degradation.

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