One pot gamma radiation mediated interfacial engineering of P-N synergistic flame retardant and antibacterial cellulose fabric: novel fabrics for future applications

Abstract

The work describes an ionizing radiation mediated, toxic solvent free interfacial engineering of a novel Phosphorus-Nitrogen functionalized bifunctional cotton cellulose fabric (BCF) endowed with flame retardant (FR) and antibacterial properties. Monomers bis[2-(methacryloyloxy)ethyl] phosphate (B2MEP) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAETC) in different proportions were co-grafted onto cellulose fabric via ⁶⁰Co radiation mediated Simultaneous Irradiation Grafting Process (SIGP) to incorporate Phosphorus and Nitrogen functionalities. Effects of radiation dose, monomer concentration on the grafting yield (GY) were investigated and samples were characterized using TGA, ATR-FTIR, XRD, SEM–EDX, EDXRF, CHN Elemental Analysis and XPS analytical techniques. Limiting oxygen index (IS:13501/ASTM D 2863) and vertical flammability tests (IS11871-1986) were conducted to establish the halogen free, P-N synergistic FR properties of the fabric. All the co-grafted samples were observed to possess LOI values in excess of 30%, while BCF (1:2) (GY =  ~ 44%) demonstrated LOI of 32% with the least char length of 74 mm in the vertical flammability tests. Tear strength studies were carried out as per ASTMD 1424-09. Antibacterial assay revealed that the fabric possessed activity against both gram positive (S. aureus) and gram negative (E. coli) organisms, with BCF (1:4) (GY =  ~ 48%) demonstrating complete killing of ~ 5 log cycles for both microorganisms in 24 h. BCF retained its FR and antibacterial properties even after multiple washing cycles. With its bonafide green credentials, durability and unique properties, multifunctional BCF fabric prepared under optimized conditions of P/N ratio > 1.7 and GY ~ 45% can be a potential candidate for future applications.