Featured are biodegradable polymers comprising repeat units derived from
cyclic phosphate monomers and optionally further comprising repeat units
derived from lactide or caprolactone monomers. Also featured are methods
for preparing the biodegradable polymers of the invention and
biodegradable polymer compositions comprising a biologically active
substance and a biodegradable polymer. Additionally featured are articles
and microspheres prepared from biodegradable polymers and polymer
compositions of the invention. Further, methods for the controlled release
of a biologically active substance using the biodegradable polymers of the
invention are also described.