Highly transparent, UV-shielding and flame-retardant P-N-Si hybridized cellulose films

Traditional cellulose films lack both effective UV-shielding and durable flame-retardant properties, limiting their use in transparent packaging and protective. In this study, a highly transparent, UV-shielding, and flame-retardant cellulose composite film was fabricated via a solvent-exchange route. Water-insoluble triphenyl phosphate (TPP) flame retardant was diffused through ethanol into regenerated cellulose (RC) gel prepared by NaOH/urea/H 2 O low temperature dissolving system, followed by post-treatment with 3-aminopropyltriethoxysilane (KH550) ethanol solution to improve the compatibility between TPP and RC and drying. The obtained PNSi-RC films exhibit visible-light transmittance exceeding 85% and demonstrate improvement in UV shielding capability. Moreover, the PNSi 7 -RC film achieved a limiting oxygen index (LOI) of 29 and a UL-94 V-0 rating, exhibiting good flame-retardant property. The films remained largely consistent flame-retardant performance after water exposure for 24 h, and the LOI values were almost no changes. This simple strategy can be scalable to the preparation process of other films for green flame-retardant packaging and protective.