Preparation, structure and properties of multi-functional silk via ATRP method

In order to develop multi-functional silk materials, silk was grafted using the first flame retardant monomer, dimethyl methacryloyloxyethyl phosphate (DMMEP), and the second antibacterial monomer, dimethylaminoethyl methacrylate (DMAEMA), via atom transfer radical polymerization (ATRP) method. The result of attenuated total reflection-Fourier transformed infrared spectroscopy (ATR-FTIR) indicated that two monomers were successfully grafted onto silk surface. X-ray diffraction (XRD) curves showed that grafting mainly occurred at the amorphous region of silk fibers. Thermal gravimetric analysis (TGA) and flame retardance measurements indicated that the Silk-grafted-poly(DMMEP) (Silk-g-PDMMEP) and Silk-grafted-poly(DMMEP)-blocked-poly(DMAEMA) (Silk-g-PDMMEP-b-PDMAEMA) both had good flame retardance. The LOI value could reach 31.2% and the char length was less than 6 cm for the Silk-g-PDMMEP sample with 22.21% of grafting percentage, and the LOI value was still over 28% after 50 times of washing. And the second grafts of DMAEMA monomer had no distinct effect on the flame retardance of Silk-g-PDMMEP. The inhibition rates of quaternized grafted silk to Staphylococcus aureu and Escherichia coli were both over 88%, and had excellent washing fastness. Multi-functional silk fabric with good flame retardance and anti-bacterial property could be obtained by properly controlling the grafting percentage, which had little effect on the intrinsic properties of silk fabric.