Hydrophobic and flame-retardant coating on silk via ferric salt chelation

Abstract

The present study facilely prepared the hydrophobic and flame-retardant (FR) multifunctional coating on silk textile through ferric ion chelation route, and focused on multifunctional abilities and mechanisms of ferric salt on silk. Morphology and structure properties of the modified silk were characterised by scanning electron microscope, atomic force microscopy and X-ray diffraction analyses. The functional abilities, mechanisms and durability were also studied. The multifunctional silk with self-extinguishing ability (char length: 10.1 cm) and hydrophobic effect (water contact angle (WCA): 126.1°) could be obtained using only 0.25 g L⁻¹ ferric salt. The modified silk still had desirable functionalities after five robust launderings. The hydrophobic ability is mainly dependent on the increased surface roughness. Thermal stability and char residue analyses indicated the condensed phase FR mechanism of functional silk. The present study provides a cleaner and cost-effective process to develop hydrophobic and FR multifunctional coating on silk surface by ferric metal salt modification.