Hydrophobic surface modified calcium alginate fibers for preparing flame retardant and comfortable Janus fabrics

With the increasing violent fluctuations in temperature and humidity, alongside rising fire risks triggered by global climate change, the development of multifunctional textile materials that integrate both humidity regulation and flame-retardant protection has become crucial for ensuring human health and safety. In this paper, the hydrophobic modification of calcium alginate (CA) fibers was successfully carried out by wet spinning technology combined with an impregnation modification process. After surface modification with fluorocarbon (FC) resin, the WCA of CA-FC fibers was increased from 32 ± 0.5° to 120.5 ± 1°, achieving a successful transition of natural polysaccharide fibers from hydrophilicity to hydrophobicity. Furthermore, the inherent flame-retardant properties of FC resin synergistically enhanced the flame-retardant performance of CA fibers. Leveraging the wettability gradient, a multifunctional protective fabric with both unidirectional water conductivity and flame retardancy was developed by compounding hydrophobically modified CA-FC fibers with unmodified CA fibers. The wettability gradient between the hydrophilic CA side and hydrophobic FC side provided a robust driving force for moisture transport, enabling the Janus-CA-FC (JCF) fabrics to achieve rapid unidirectional water transport while maintaining excellent flame-retardant performance. This study lays the foundation for the development of multifunctional protective fabrics with flame retardancy and humidity management based on natural polysaccharide materials.