the present invention relates to crosslinking of porous materials made of biodegradable polymers . the method comprises : placing a porous biodegradable polymer in a chamber ; introducing a supercritical fluid containing a crosslinking agent into the chamber to effect crosslinking of the porous biodegradable polymer ; and optionally introducing a pure supercritical into the chamber to wash the crosslinked polymer until the crosslinking agent is substantially removed from the polymer .