Macromolecules 1991,24, 2283-2290
2283
Characterization of Hydrolytically Degradable Amino Acid Containing Poly(anhydride-co-imides) Andrea Staubli, Edith Mathiowitz3 Melissa Lucarelli, and Robert Langer' Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge,
Massachusetts 02139 Received May 31, 1990; Revised Manuscript Received September 24, 1990
ABSTRACT The synthesis and characterization of poly(anhydride-co-imides)containing either naturally occurring amino acids or o-amino acids linked via hydrolytically labile anhydride bonds are presented. The synthesis included initial condensation of the amino acids with trimellitic anhydride to form imide-containing diacids, followed by melt polycondensation via the corresponding mixed anhydride. The reaction conditions were optimized for both the homo- and copolymers with either sebacicacid (SA) or 1,6-bis(p-carboxyphenoxy)hexane (CPH) in defined ratios. Polymerizations performed at 180 OC gave, in general, maximal molecular weight after 1-2 h. High molecular weight was also obtained if the polymerizations were performed at lower reaction temperatures over longer periods of time. Higher molecular weight copolymers (>lo00o0) were generally obtained with an increasing content of flexible spacers. An increasing content of flexible spacers also resulted in low melting points (
