Revealing the flame retardancy of cotton fabrics treated with ammonium ethylenediamine tetramethylenephosphonate and trimethylol melamine

Phosphorus-nitrogen containing polymers have been attracting considerable interest as potential flame retardants (FR) for cotton fabrics. In this work, we report an experimental-theoretical joint study on flame retardancy of cotton fibres treated with ammonium ethylenediamine tetramethylenephosphonate (AEDTMP) as FR and trimethylol melamine (TMM) as binder. Through material characterization and FR test, we find that the cotton fabric samples treated with 5% AEDTMP and 5% TMM solutions exhibit better flame retardancy and durability than those with 25% AEDTMP solution by forming multilayer coatings on the fabrics. Our calculations within the density functional theory framework reveal that the P–O–C and C–O–C bonds are newly formed by reactions between the AEDTMP FR and TMM binder, and the multilayer coating enhances such binding reactions. Our work highlights that the multilayer coating with AEDTMP of lower density is superior for flame retardancy and durability of treated cotton.