Structural characteristics of phosphorylated cotton prepared by gas-phase procedure

Abstract

This study reports the synthesis of phosphorylated cotton fiber (Ph-CF) via a gas-phase oxidative chlorophosphorylation reaction. The process improved the crystallinity and thermal properties of raw cotton fibers (R-CF). Fourier-transform infrared spectroscopy confirmed the formation of phosphorus-containing groups, while UV-visible spectroscopy revealed increased UV absorption. X-ray diffraction showed increased crystallinity for Ph-CF, with a crystallinity index (Segal method) of 81.41% versus 41.05% for R-CF, which was attributed to the removal of amorphous components. The thermogravimetric analysis demonstrated enhanced thermal stability for Ph-CF, with a char yield of 38% at 560 °C compared to 20% for R-CF. Scanning electron microscopy revealed noticeable changes in surface morphology, including smoother and more compact fiber surfaces after modification. Energy-dispersive X-ray spectroscopy confirmed the incorporation of phosphorus into the fiber structure, with a measured phosphorus content of 2.27% in Ph-CF. The oxidative chlorophosphorylation reaction in the gas phase induced deeper chemical transformations than a similar liquid-phase process, as evidenced by enhanced crystallinity and structural modifications. These results indicate the potential of gas-phase oxidative chlorophosphorylation for functionalizing cotton with improved properties for advanced applications.