Solid-solid phase-change materials

A polyether- or polyester-epoxide polymer (PEEP) composition which comprises a reaction product of:

• (a) a polyepoxide compound having an equivalent weight within the range of 115 to 250 g/eq.;
• and
• (b) a polyol composition comprising a polyether polyol, a polyester polyol, or a mixture thereof, wherein the polyol composition has a melting point within the range of 20° C. to 100° C. and a hydroxyl number less than 35 mg KOH/g;
• wherein the ratio of epoxy equivalents of the polyepoxide compound to hydroxyl equivalents of the polyol composition is within the range of 2:1 to 6:1;
• and
• wherein the PEEP composition is a solid-solid phase-change material having, as measured by differential scanning calorimetry (DSC) at a heating/cooling rate of 10° C./minute, a transition temperature within the range of 15° C. to 50° C., a latent heat at the transition temperature within the range of 30 to 200 J/g, and little or no detectable hysteresis or supercooling upon thermal cycling over at least five heating/cooling cycles that encompass the transition temperature wherein the little or no detectable hysteresis or supercooling is evidenced by a variation in transition temperature in any heating or cooling transition of less than 2° C. over the at least five cycles.