Thermo and light-responsive phase change nanofibers with high energy storage efficiency for energy storage and thermally regulated on–off drug release devices

Thermo/light-responsive functionalized cellulose nanocrystal-zinc oxide (f-CNC-ZnO) nanohybrids based poly (3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) phase change nanofiber (PCF) composites with highly thermal energy storage ability were developed for controllable drug release applications. Under sunlight irradiation, the PCF composite (without f-CNC-ZnO) absorbed light and stored the thermal energy with 46.3% efficiency. An "on–off" temperature regulation of tetracycline hydrochloride (TH) release was found for PCF composites according to phase change temperature. At the temperature close to the melting point of PEG at 60 °C, the PCF composite with 5 wt% f-CNC-ZnO displayed a sustained release of more than 40.5 and 78.9% of tetracycline hydrochloride (TH) were released over two weeks for the 10 and 30 wt% drug loading. Thus, the PCF composites with excellent thermo/light-responsive properties and high energy storage efficiency are beneficial for promising sustainable thermal storage and drug delivery systems.