In-situ phosphine oxide physical networks: A facile strategy to achieve durable flame retardant and antimicrobial treatments of cellulose

Rashid Nazir,Ezgi Bülbül,Anja Huch,Dambarudhar Parida,Simon Annaheim,Sabyasachi Gaan,Qun Ren,Joel Borgstädt,Milijana Jovic,Stefanie Altenried,Daniel Rentsch,Patrick Rupper,Sandro Lehner

doi:10.1016/j.cej.2020.128028

Abstract

• Cotton cellulose was modified via in situ phosphine oxide macromolecules. • Phosphorus monomer was crosslinked with amine via Michael addition reaction. • Excellent flame retardancy and durability to 50 laundry cycles was achieved. • Hydrophilicity and comfort properties of the treated fabrics were enhanced. • Antimicrobial property was achieved via in situ silver nano particle treatment. A facile methodology to durably modify cellulose fibers by forming in-situ phosphine oxide macromolecular physical networks is developed in this work. Such networks were formed by treating the cellulose fibers with a mixture of Michael adducts [trivinyl phosphine oxide (TVPO) and cyclic amines (piperazine and 2,4,6-tri(piperazine-1-yl)-1,3,5-triazine)] followed by a click crosslinking reaction initiated by dry heat, microwave, or steaming process. The in-situ phosphine oxide network is integrated within the cellulose fibers to produce a durable treatment against laundering. NMR and SEM analysis of the treated fibers verified the in-situ formation of phosphine oxide macromolecules in the bulk of cellulose fiber. The treatment was homogenous and achieved an outstanding phosphorus (P) retention (>95%) after even 50 laundry cycles. The treated cotton exhibited excellent fire retardant properties with a limiting oxygen index value >27% and passed the Swiss vertical flammability test at 2 wt% P. Analysis of evolved gasses during thermal decomposition of treated cellulose supported both the condensed and gas phases mechanism. The flame retardant treatment was further adapted to include antimicrobial properties by in-situ formation of silver nanoparticles within the cellulose fibers using a single-step process to demonstrate the versatility of this novel treatment methodology. The treated fabric exhibited excellent antimicrobial as well as flame retardant properties and was also durable to 50 laundry cycles. Contact angle measurements and moisture management test confirmed the excellent comfort behavior of the treated cellulose fabric.

Highlights

There is a growing demand to develop protective textiles for emer gency workers, technical, security, and military personnel, to reduce exposure to biological, chemical, and fire threats [1,2,3]
The hydroxyl groups present in cellulose provide synthetic access points for various flame retardant (FR) that primarily function in the condensed phase
Formaldehyde-free flame retardant treatments for cotton cellulose have been a challenge for researchers over the last few decades with no clear solution which has been commercialized

Summary

Introduction

There is a growing demand to develop protective textiles for emer gency workers, technical, security, and military personnel, to reduce exposure to biological, chemical, and fire threats [1,2,3]. Increased use of polymeric materials in building construction [3,4] and climate change [5], has led to an increase in fire incidents, which has resulted in the catastrophic wildfire, civilian and deaths, injuries, and property dam age. Novel multifunctional materials that can aid in minimizing these threats are of great importance to today’s society. Textiles are considered the first line of personal defense against the above-mentioned threats [7]. To address these challenges, innovations in textile construction and material components are of paramount importance. As renewable and biodegradable materials, they are considered sustainable compared to most engineered fibers [8]. How ever, like most organic materials, they burn and require

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Results

Conclusion