Multifunctional modification of silk fabrics via a combination of sophora flower extract, phytic acid and silicone-containing organics: Flame retardancy, water repellency, antibacterial activity and ultraviolet resistance

Herein, a multifunctional composite coating is constructed on silk fabrics by a facile impregnation strategy. In detail, the pre-period involves the aggregation growth of sophora flower extract/phytic acid-lanthanum ion-silk fibroin complex network, while the post-period introduces a water repellent layer that is composed of hydroxyl-terminated polydimethylsiloxane and hexadecyltrimethoxysilane composite. Benefiting from the synergistic effect of P, Si and N elements, the optimized finished silk sample denoted as D/FR/W R -SF exhibits a limiting oxygen index value of up to 29.3%, and shows a damage length as low as 9.4 cm in the vertical burning test. Since the sophora flower extract contains flavonoids such as rutin and quercetin , it confers good antibacterial activity and ultraviolet resistance to silk fabrics. The results display that D/FR/W R -SF inhibits the colony propagation of Escherichia coli and Staphylococcus aureus , and achieves an ultraviolet protection factor value of 38.61 compared with the control silk fabrics. Attributed to the directional arrangement of long-chain alkane and Si-CH 3 , D/FR/W R -SF exhibits good water repellency with a water contact angle of 138°. Additionally, D/FR/W R -SF also presents satisfactory washing resistance (integrated properties after 25 laundering cycles). Therefore, such a complete multifunctional composite coating scheme shows great potential for expanding advanced textile applications.