Hollow Spongy Phase Change Composite Fiber with Heat Storage Behavior via Photo-Thermal Transition

A phase change fiber was prepared by loading poly(ethylene glycol) (PEG) in the hollow fiber (HFF). HFF showed a high loading capability (50–65%) of PEG. The enthalpy value of the phase change fiber (P-HFF) was 94.69 J/g when the PEG loading was 65%. The phase change fiber had a thermoregulation function in the range of 36–40 ℃, and the heat releasing worked for about 280 s. P-HFF had a thermal conductivity of 0.079 Wm⁻¹ K⁻¹. Carbon nanotubes (CNT) were doped in PEG to increase thermal conductivity of P-HFF. With the increase of CNT content, the thermal conductivity of CNT modified phase change fiber (PC-HFF) increased up to 0.125 Wm⁻¹ K⁻¹. Polypyrrole (PPy) was coated on the surface of HFF via in situ polymerization. The prepared photothermal phase change fabric (PPy-PC4-HFF) had a photothermal conversion rate as high as 84.23%. The surface temperature of PPy-PC4-HFF reached 77 ℃ at one solar intensity (1000 W m⁻²) after more than 700 s of light exposure. The generated heat was efficiently absorbed by the loaded PEG. This type of fiber had a function of thermoregulation that could regulate the temperature of the human body in response to changes of the environment.