LAUSR

Abstract This study reported a facile and sustainable modification of cellulose by plant tannins and chitosan polymer for higher impregnation of UV protective natural chromophores (UVPNCs) derived from the banana floral stem (BFS). The phytochemical screening demonstrated that BFS extracts have different UVPNCs including condensed tannin, flavonoids, anthocyanin, betacyanin and anthraquinone. The optimized impregnation temperature and time for UVPNCs entrapping were found at 80 °C with a time interval of 60 min and the overall inherent fixation rate of UVPNCs was ranging from 53 to 63%. The cellulose substrate templated with plant tannins (extracted from Terminalia chebula and Phyllanthus emblica) and chitosan improved the UVPNCs absorption amount almost 2 and 1.8 folds, respectively, which was expressed in terms of color strength (K/S). Interestingly, the UVPNCs entrapping ability of bio-crosslinked cellulose was also higher than typical metallic salts treated cellulose. The higher absorption mechanism of UVPNCs for tannins (-OH and –COOH) and chitosan (-NH2) templating have been discussed in terms of molecular orientation (TCI, LOI), inter and intra-molecular hydrogen bonding configuration (HBI, EH, R), and the total amount of anchored-UVPNCs which was expressed by the asymmetric factor (AF). The UV shielding property of the UVPNCs impregnated modified cellulose was compared and a maximum of two folds higher UPF value was found in bio-templated cellulose substrate (UPF range = 223 to 459) than metal treated cellulose substrates (UPF range = 163 to 175). Furthermore, the functional durability of UVPNCs impregnated substrates was evaluated in terms of several colorfastness and found very good to excellent grading.