U.S. patent application 20190014932 (applicant Raymond Booska, Melbourne, Fla.):
"A liquid receptacle has an inner vessel for holding a liquid, an insulated outer shell spaced from the inner vessel, and a chamber defined between the inner vessel and the outer shell. A phase change material is disposed in the chamber for absorbing thermal energy from the liquid and then releasing the thermal energy back to the liquid to maintain the temperature of the liquid. ... In some versions, a second phase change material is disposed within the second chamber. This phase change material has a phase change temperature different than the first phase change material. The phase change temperature of the second phase change material may be different than the phase change temperature of the first phase change material."