A novel durable flame retardant rich in phosphate ester groups for cotton fabrics

A novel N–P flame retardant (FR) named the ammonium salt of 1,3-diaminopropane tetramethylene dimethyl triphosphonate phosphonic acid (ASAPMPA) was synthesized for surface modification of cotton fabrics. Introducing large amounts of phosphate ester groups (−P=O(OCH3)2) into ASAPMPA could limit the exchange of metal ions and improve the durability of treated cotton. FT-IR, XPS and washing resistance tests of ASAPMPA-treated cotton suggested ASAPMPA was grafted onto cotton cellulose by P–O–C; TG results showed that ASAPMPA obviously promoted char generation and thermal properties of cotton fabrics, indicating ASAPMPA-treated cotton had excellent flame retardancy. The limiting oxygen index (LOI) of 30% ASAPMPA-treated cotton was 48.0%, and remained at 34.4% after 50 laundering cycles (LCs) following AATCC 61-2013 2A standard, revealing its high flame retardancy and launderability. EDS results confirmed that introducing −P=O(CH3)2 could decrease the metal ions exchange efficiently; SEM and XRD results suggested the morphology and structure of treated cotton were retained basically. Bending length and breaking strength results showed there was only a slight decrease in the physical performance of treated cotton.