Graphene-integrated flexible films with a three-dimensional elastic network and photothermal responsiveness

Soft and flexible polymer films with integrated functional responsiveness are highly desirable for wearable and deformable devices, but achieving mechanical compliance together with photothermal functionality remains challenging. Herein, a series of photocrosslinked elastic films were fabricated from poly(l-lactide-co-ε-caprolactone)-b-poly(ethylene glycol)-b-poly(l-lactide-co-ε-caprolactone) diacrylate (PLCL-PEG-PLCL DA) using a pentaerythritol tetrakis(3-mercaptopropionate) (PETMP)-assisted thiol-ene strategy, followed by the incorporation of graphene to construct a soft photothermal composite film. A fully amorphous elastic network of the photocrosslinked films could be systematically tuned by varying the PETMP content. Increasing PETMP content improved the elongation at break, while the incorporation of graphene further enhanced the toughness and extensibility of the elastic network without compromising flexibility of the films. The water uptake, wettability, and degradation behavior of the films were also tunable. Notably, the graphene-containing film showed rapid photothermal heating under near-infrared irradiation, with the surface temperature increasing from 24.2 to 50.6 °C within 60 s. This work provides a simple strategy for designing soft photothermal elastic films.