A method of cancer hyperthermia therapy includes placing a device including an exogenously-excitable polymeric material at a cancer hyperthermia therapy site of a patient. The method also includes supplying an exogenous energy to the device such that the exogenous energy excites the exogenously-excitable polymeric material at the cancer hyperthermia therapy site to heat the cancer hyperthermia therapy site to a hyperthermia temperature. A method of preparing a polymeric material includes combining an alcohol monomer, a seed of the polymeric material, and an aqueous liquid in a vessel. The method also includes adding an acid monomer to the vessel and supplying an exogenous energy to the vessel. The polymeric material is exogenously excited by the exogenous energy to heat the polymeric material. The method further includes removing water from the vessel and producing the polymeric material, which is a polyester, in the vessel.