A polymer of siloxanes as flexibility monomers and strength monomers is provided. It is also provided a polymer blend that contains a polymer formed of siloxane monomers and strength monomers and another biocompatible polymer. The biocompatible polymer or polymer blend described herein and optionally a bioactive agent can form a coating on an implantable device such as a drug-delivery stent. The implantable device can be used for treating or preventing a disorder such as atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation for vein and artificial grafts, bile duct obstruction, ureter obstruction, tumor obstruction, or combinations thereof.