A versatile flexible film containing phase change microcapsules and polypyrrole/bacterial cellulose with high enthalpy, photothermal and Joule heating for personal thermal management

Flexible phase change films have received considerable attention for their potential applications in personal thermal management (PTM). However, it is still a huge challenge to develop PTM materials combined with all desired functions, including high flexibility, latent heat, electrical conductivity, photothermal conversion, Joule heating, and mechanical strength. Herein, we reported a versatile flexible phase change film (DBT) for PTM by combining docosane microcapsules (C 22 -CMP) and bacterial cellulose coated with polypyrrole (BC/PPy) into thermoplastic polyurethane (TPU) elastomer. C 22 -CMP microcapsules with cellulose nanocrystal (CNC)/melamine–formaldehyde (MF)/PPy as shells were prepared with CNC stabilized Pickering emulsion via in-situ formation of MF and PPy, and displayed high anti-leaking stability and latent heat. The BC/PPy with a high aspect ratio was employed as the conductive nanofiller to construct 3D conductive networks of TPU. The obtained DBT-334 film possessed high latent heat (64.3 kJ/kg), photothermal conversion ability (80 °C under light irradiation at 1.0 W/cm 2 ), electrical conductivity (9.26 S/m), Joule heating (48.1 °C at 5 V), flexibility, and sufficient mechanical strength (elongation at break of 6.0 % and Young’s modulus of 12.9 MPa), making it promising as PTM. Moreover, the applications of DBT for solar thermoelectric generation and motion sensing were also demonstrated.