Construction of transparent cellulose films with enhanced mechanical strength, fire resistance and UV to blue light shielding performance via hydrogen bond-electrostatic synergistic interaction

Cellulose-based functional film materials play an irreplaceable role in daily life due to their non-toxicity and biodegradability. However, poor flame retardancy and UV to blue light blocking performance limit their application. Herein, a facile and eco-friendly impregnation-adsorption strategy was proposed to fabricate transparent and biodegradable multifunctional cellulose films. Safflower yellow (SY) and phosphorylated sodium alginate (PSA) are used as functional components to give films powerful light blocking performance, exhibiting UV-A and UV-B blocking efficiencies spanning from 89.2 % to 98.9 % and 87.9–98 %, respectively. Meanwhile, the films could block 89.8–98.9 % of high-energy blue light (HEBL) while retaining high transmittance (80.8–83.8 % at 600 nm). Meanwhile, the films are effective at blocking HEBL that comes from lighting system, computer screen, and smartphone screen. Compared with commercial shielding films, the films demonstrated superior capabilities in filtering out UV and HEBL. Furthermore, the film exhibits stable UV and HEBL shielding properties under both thermal treatment and UV irradiation. Encouragingly, the introduction of PSA empowered the films to gain the required flame retardancy, resulting in the limiting oxygen index (LOI) surging notably from 19.1 % to 33.4 %. The peak heat release rate and total heat release of the films were significantly reduced from 183.9 to 61.7 W/g and from 8.9 to 1.9 KJ/g, respectively. Based on the hydrogen bond-electrostatic synergistic interaction among cellulose, SY and PSA, the tensile strength of films has significantly increased by 16.8–20.5 %. Additionally, these films possess favorable biodegradability. On account of extraordinary capabilities, the films demonstrate diversified applications.