Silk fibroin/fluorinated POSS polymer/quaternized carboxymethyl chitosan: A hydrophobic and antibacterial reinforcement system for silk cultural relics.

Silk cultural relics, as valuable carriers of history and culture, are highly susceptible to degradation by water and microorganisms, which poses a long-term challenge for silk artifact conservation. Herein, a new comprehensive silk cultural relic reinforcement system with hydrophobicity and antibacterial properties was constructed by introducing fluorinated POSS polymer (PAT) and quaternized carboxymethyl chitosan (QCMCS), using silk fibroin (SF) homologous to silk cultural relic based on covalent bond and non-covalent bond strategies. The covalently crosslinked reinforcement system attaches to aged silk via hydrogen bonding and physical entanglement to enhance its mechanical properties and aging resistance. Notably, the presence of fluorine-containing chain segments and cationic ammonium groups in the reinforcement system effectively enhanced the hydrophobic, antibacterial, and antifungal properties of the aged silk. The reinforced aged silk exhibited a high water contact angle (128.9°) and inhibited E. coli, S. aureus, and A. niger by over 97%, with a minimal color change (ΔE = 0.82). Altogether, this work provides a promising strategy for silk fibroin-based reinforcement and presents new insights into the design of hydrophobic and antimicrobial systems for the preservation of silk cultural heritage.