Effect of fabrication technique on the erosion characteristics of polyanhydride matrices

The aim of this study was to investigate the effect of device fabrication technique on the erosion characteristics of poly[1,3-bis(p-carboxyphenoxy) propane:sebacic acid] [p(CPP:SA)] 20:80 copolymer. Devices were prepared using melt-molding, solvent-casting, and compression-molding techniques and their erosion was followed by determining changes in device morphology, molecular weight, water uptake, mass loss, and release of monomers, with time of immersion in phosphate buffer pH 7.4 at 37 degrees C. Melt-molded devices had a very dense and uniform structure and displayed characteristics typical of surface eroding systems. Devices produced using a solvent-casting technique had a very porous structure with no detectable erosion zone and the erosion profiles were indicative of bulk rather than pure surface erosion. Compression-molded devices had a dense structure and revealed a faster rate of erosion than melt-molded devices. A comparison of the extent of changes of polymer molecular weight, water uptake, mass loss, and monomer release showed a marked dependence on the method of fabrication.