Construction of nano-multilayer coatings on copolyester fabrics using UV-grafting mediated layer-by-layer self-assembly for improved anti-droplet and flame retardent performance

Abstract

Aiming to realize anti-dripping and improve fire retardancy of polyester fabrics, novel hybrid multilayer nano-coatings composed of γ-amino propyltriethoxysilane (KH-550), bio-based betadex sulfobutyl ether sodium (SBE-β-CD) and [(6-Oxido-6H-dibenz-[c,e][1,2]oxaphosphorin-6-yl)methyl] butanedioic acid (DDP), were successfully constructed through layer-by-layer self assembly (LBL) method. Polyacrylic acid (PAA) layer were firstly deposited onto polyester fabrics via UV-grafting, facilitating the following electrostatic adhesion for bi-layer electrolytes. The LBL assembly electrolytes as well as coating thickness were investigated in order to have a better optimization of the nano-coatings with the desired flame resistance properties. The morphological analysis, thermal stability, flame retardant properties of multilayer modified polyester were carried out by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS), thermogravimetry analysis (TGA), limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT), respectively. After the functional multilayer coated, the ignition time was delayed. Moreover, total heat release and peak heat release rate were reduced but char residues increased. Of particular significant is the melt dripping phenomena disappearance in optimum condition of (K/S)6+(K/D)3 hybrid LBL coatings with LOI value of 36% and V-0 rating in UL-94 test. The analysis of SEM, fourier transform infrared spectrometer (FITR) and X-ray photoelectron spectroscopy (XPS) results of the residual char indicated a compact exterior layer but multicellular structures for interior layer with thermodynamically stability SiO2, which was served as a barricade shield to protect the underlaying polymer matrix during the combustion process. This suggested that both condensed-phase and gas-phase flame-retardancy made contributions to the flame retardant mechanism. The synergistic effect of hybrid LBL multilayer surface could impart polyester fabrics with high fire retardancy and non-dripping performance.