Erosion of a 1,3-Bis(p-carboxyphenoxy)propane−Sebacic Acid Poly(anhydride) Copolymer by Water Vapor Studied by 1H and 13C Solid-State NMR Spectroscopy

The erosion of a 1,3-bis( p -carboxyphenoxy)propane−sebacic acid poly(anhydride) copolymer, p(CPP:SA), by water vapor has been studied by 1 H wide-line and 13 C MAS solid-state NMR spectroscopy. In contrast to erosion by phosphate buffer, no mobile absorbed water was detected. 1 H T 1, T 1 ρ, and line width data indicated that the polymer matrix became more rigid on erosion due to the formation of crystalline degradation products. From the 13 C spectra, the hydrolysis of the anhydride links into SA and CPP carboxylic acid groups was determined quantitatively. The rate of hydrolysis by water vapor was comparable to that by phosphate buffer. The SA−SA and SA−CPP links were hydrolyzed at comparable rates, and both were hydrolyzed more rapidly than CPP−CPP links.