Poly(octadecanoic anhydride) (POA) has been
prepared by melt polycondensation of octadecanoic diacid.
POA was characterized by Fourier-transform infrared
spectroscopy (FTIR), differential scanning calorimetry
(DSC) and wide angle X-ray diffraction (WAXD). The
results of in vitro degradation and SEM micrographs show
that the erosion process of POA is neither bulk nor perfect
surface erosion but rather has elements of both in phosphate
buffer at 37 C. The moving erosion front is characteristic
of surface erosion whereas the remaining porous
shell stems from bulk erosion. While a significant special
degradation property of POA is that POA presents a very
slow degradation rate in acidic condition (pH 5.98), only
1.64% weight loss for 20 days, and it completely degrades
after 18 days in basic buffer (pH 7.4). Comparing with
poly(sebacic anhydride) (PSA), POA has the higher crystallization
degree, and the slower hydrolytic rate.