Abstract:

For producing multifunctional ecological cotton fabrics, cotton fabrics were selectively oxidized by HNO3/H3PO4-NaNO2 mediate system to introduce the carboxyl groups in cellulose, and then fibroin was bonded with oxidized cotton fabric by the amide reaction. The influence of oxidation time of HNO3/H3PO4-NaNO2 on carboxyl content and tensile strength of oxidized cotton fabrics was studied, and the influence of oxidation time, mass concentration and treatment time of fibroin on graft yield of oxidized cotton fabric was investigated and the fibroin graft yield of 10.43% was obtained when the oxidation time and graft time were chosen as 1 h and 2 h, respectively. The analysis of NMR, FT-IR, SEM and XPS illustrated that the primary hydroxyl at C6 position in glucose units of cotton fiber was selectively oxidized to carboxyl group by HNO3/H3PO4-NaNO2 system, subsequently the amido bond of C-N was formed by the reaction between amino groups in silk fibroin and carboxyl groups in oxidized cotton fabric and the fibroin film covered on the surface of oxidized cotton fabrics by the covalent crosslinking. The breaking strength and whiteness of fibroin grafted cotton fabrics slightly decreased, whereas the properties of wrinkle recovery and moisture adsorption of modified fabrics markedly increased. 3.45 times as much honeysuckle extract adsorbed on the fibroin grafted cotton fabric was released than original cotton fabric. Furthermore, the fibroin grafted carboxylic cotton fabric treated with honeysuckle extract had a good antimicrobial activity against Staphylococcus aureus and Escherichia coli after 30 washes by water.

Key words: silk fibroin, cotton fabric oxidized in C6 position, amide crosslinking, honeysuckle extract, controlled release