Flexible and photo-responsive composite phase change materials for thermal therapy

The medical dressings with appropriate temperature can relieve body pain by promoting blood circulation. In order to endow the thermal compress dressings with multifunction and facilitate their application in different scenarios, the flexible films employing paraffin (PF) as thermal energy storage medium, styrene-ethylene/butylene-styrene (SEBS) triblock copolymer as matrix and graphene as photo-thermal conversion agents were fabricated. The film containing 77 wt% of PF has high latent heat of 157.26 J·g−1 and exhibits smooth and dense morphology. The film also exhibits tensile strain of 2576.75 %, photothermal conversion efficiency of 70.52 % and enviable self-healing properties, which makes it possible to meet the needs of different body parts and reuse in practical applications. In addition, under natural sunlight, the thickness of 3 mm thermal film can maintain the temperature ranging from 40 °C to 50 °C for more than 25 min; under the action of an electrically heated film, the film can maintain at 40 °C to 50 °C for about 22 min. The extraordinarily long thermal therapy time and suitable thermal therapy temperature are remarkable. In summary, the excellent thermal storage properties, mechanical properties, self-healing properties and photothermal conversion properties make it a good application prospect for thermal therapy.