U.S. patent application 20190249058 (applicant Technogel Italia S.r.L., Pozzoleone, Italy):
"A method for the production of a temperature regulating polyurethane gel composition and corresponding articles includes fatty acid esters as a phase change material (PCM) directly incorporated in the fluid phase of a polyurethane gel without encapsulation. The liquid or melted PCM is solved in the polyol component of the gel and is able to crystallize and melt within the gel structure reversibly. The polyurethane gels are under-crosslinked and include an at least nominal three functional ethylene oxide-comprising alkylene oxide polyether polyol with 0 to 40% EO and an isocyanate with an effective functionality of from 1.5 to 3.5. The gels are useful in articles where the gel can be positioned close to the human body for temperature regulating purposes, and especially to improve the sleeping comfort of a resting person."