Flame Retardant-Functionalized Cotton Cellulose Using Phosphonate-Based Ionic Liquids

Abstract

Cellulose from cotton fibers was functionalized through a dissolution–regeneration process with phosphonate-based ionic liquids (ILs): 1,3-dimethylimidazolium methylphosphonate [DIMIM][(MeO)(H)PO2] and 1-ethyl-3-methylimidazolium methylphoshonate [EMIM][(MeO)(H)PO2]. The chemical modification of cellulose occurred through a transesterification reaction between the methyl phosphonate function of ILs and the primary alcohol functions of cellulose. The resulting cellulose structure and the amount of grafted phosphorus were then investigated by X-ray diffraction, ICP-AES, and ¹³C and ³¹P NMR spectroscopy. Depending on the IL type and initial cotton / IL ratio in the solution, regenerated cellulose contained up to 4.5% of phosphorus. The rheological behavior of cotton cellulose/ILs solutions and the microscale fire performances of modified cellulose were studied in order to ultimately prepare flame retardant cellulosic materials. Significant improvement in the flame retardancy of regenerated cellulose was obtained with a reduction of THR values down to about 5–6 kJ/g and an increase of char up to about 35 wt%.

A highly efficient chemical approach to producing green phosphorylated cellulosic macromolecules

“…Several studies have shown that the presence of phosphate groups prevent the spread of ames by preventing the diffusion of the oxidant, oxygen, inside the material. 25,27,40,57 The phosphate groups form a protective shell. To better understand the mechanism of decomposition and the formation of the protective layer by the phosphate groups, we refer to what has already been done in this eld.…”

“…[20][21][22][23][24] This modication is an essential step in order to obtain some needed properties, which are not normally found in the original cellulose structure. Thus, phosphorylated cellulose bers have many advantageous properties that render them highly promising in many applications, such as composites, 25 ame retardant materials 3,5,[26][27][28] and lters for the removal of heavy metals. 29,30 The hydroxyl groups in the cellulosic chain can be modied and functionalised via diverse chemical pathways, some requiring low energy consumption that is necessary to produce greener bers with new and required properties.…”

Ionic Liquids Grafted Cellulose Nanocrystals for High-Strength and Toughness PVA Nanocomposite

“…The single mass loss and high weight residual content of CNC-LA-IL can be interpreted by the hypothesis that the surface of the CNC is wrapped with shell-like structure covalently bonded ILs with flame-retardant properties. The residual components of thermally degraded CNC and CNC-LA at high temperature should be the charred residues of cellulose, and the higher charred residues have also been reported for the modified cellulose in the literature. ,− …”

A Review on the Modification of Cellulose and Its Applications

“…Water is environment friendly, economical, and with no risk, whereas on the other side, the toxicities of organic chemicals studied ranged in many categories. The least toxic chemicals, such as ethanol, methanol, acetone, and acetonitrile, were commonly observed for the regeneration of cellulose from solutions [ 132 ].…”