Bio-inspired and dual interaction-based layer-by-layer assembled coatings for superior flame retardancy and hydrophilicity of polyamide 6.6 textiles. (15th March 2021)

• Record Type: Journal Article
• Authors: Rahman, Mohammad Ziaur; Kundu, Chanchal Kumar; Wang, Xin; Song, Lei; Hu, Yuan
• Is Part Of: European polymer journal. Volume 147(2021)
• Publication Date: 2021-03-15
• Subjects: Covalent interaction -- Chitosan -- Super-hydrophilicity -- Flame retardancy -- Coating stability -- Polyamide 6.6 fabrics; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2021.110320
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: A dual interaction-based and bio-inspired LbL assembled coating was prepared. Improved flame retardancy and super-hydrophilicity of PA6.6 fabrics were realized. Simultaneous PCS grafting and LbL deposition with 8 QLs raised LOI value up to 23.5%. A reduction in pHRR by 45% and in THR by 25% was achieved with 8 QLs deposition. The dual-interaction in LbL assembly could stabilize coatings up to 20 laundering cycles. Abstract: A dual interaction-based (i.e., ionic/covalent) deposition of carbohydrate polymers, namely chitosan (CS) and oxidized sodium alginate (OSA) along with a plant-derived phosphorus-rich compound like phytic acid (PA) and a nitrogen rich compound like melamine (ME) was considered onto the phosphorylated chitosan (PCS) modified polyamide 6.6 (PA6.6) fabric surfaces in order to impart durable flame retardancy along with super-hydrophilicity of the same. Firstly, the pure PA6.6 textile surfaces were modified by PCS via UV-induced grafting and subsequently, the above-mentioned polyelectrolytes were assembled onto the fabric surfaces in a quadralayer fashion [i.e., (CS/ME-OSA-CS/ME-PA) n ; "n" represents the number of quadralayers (QLs)]. Here, the amino groups of CS/ME and the aldehyde groups of the OSA were stabilized via covalent interaction and the deposition of positively charged CS/ME and negatively charged phytic acid (PA) formed ionic interaction. In the vertical burning (UL-94) test, both the only PCS grafted and the simultaneously PCS-grafted along with LbL assembled fabrics could completely stop the melt dripping tendency and attained a V-1 rating. In the meantime, the limiting oxygen index (LOI) value received a moderate increase from 18.5 % of pure PA6.6 to 23.5 % for the PCS grafted and 8-QLs deposited fabric sample (i.e., PA6.6-g-PCS-8QL). Moreover, the PA6.6-g-PCS-8QL fabric sample exhibited a dramatic decrease in the peak heat release rate (pHRR) and total heat release (THR) by about 45 % and 24.7 % respectively alongside enhanced thermal stability. Apart from the appreciable flame retardancy, this fabric sample (i.e., PA6.6-g-PCS-8QL) could boost up the hydrophilicity to attain a water contact angle of 0°. Finally, this dual interaction-based deposition of bio-inspired polyelectrolytes posed a positive impact in enhancing the coating stability in laundering and imparting durable flame retardancy to sustain even up to 20 laundering cycles.