Functionalization of MXene Nanosheets for Polystyrene towards High Thermal Stability and Flame Retardant Properties

Abstract

Fabricating high-performance MXene-based polymer nanocomposites is a huge challenge because of the poor dispersion and interfacial interaction of MXene nanosheets in the polymer matrix. To address the issue, MXene nanosheets were successfully exfoliated and subsequently modified by long-chain cationic agents with different chain lengths, i.e., decyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium bromide (OTAB), and dihexadecyldimethylammonium bromide (DDAB). With the long-chain groups on their surface, modified Ti3C2 (MXene) nanosheets were well dispersed in N,N-dimethylformamide (DMF), resulting in the formation of uniform dispersion and strong interfacial adhesion within a polystyrene (PS) matrix. The thermal stability properties of cationic modified Ti3C2/PS nanocomposites were improved considerably with the temperatures at 5% weight loss increasing by 20 °C for DTAB-Ti3C2/PS, 25 °C for OTAB-Ti3C2/PS and 23 °C for DDAB-Ti3C2/PS, respectively. The modified MXene nanosheets also enhanced the flame-retardant properties of PS. Compared to neat PS, the peak heat release rate (PHRR) was reduced by approximately 26.4%, 21.5% and 20.8% for PS/OTAB-Ti3C2, PS/DDAB-Ti3C2 and PS/DTAB-Ti3C2, respectively. Significant reductions in CO and CO2 productions were also obtained in the cone calorimeter test and generally lower pyrolysis volatile products were recorded by PS/OTAB-Ti3C2 compared to pristine PS. These property enhancements of PS nanocomposites are attributed to the superior dispersion, catalytic and barrier effects of Ti3C2 nanosheets.

Mechanotribological Aspects of MXene‐Reinforced Nanocomposites

“…It should be noted that the solubility of MXene in nonpolar polymers or those with weakly polar groups is still challenging and hence a suitable surface premodification needs to be adopted for enhancing dispersibility. [61,62] As yet, different MXene nanomaterials have pervaded in many polymers such as polyurethane, [62] polyfluorenes, [63] polylactic acid, [64] polyethyleneimine, [65] Nafion, [57] polyacrylamide, [38,66] cellulose, [8,67] polyethylene oxide, [68] polyvinyl alcohol, [69,70] chitosan, [71] polybenzimidazole, [72] polyvinylidene fluoride (PVDF), [60] and polyacrylate acrylic resin, [73] etc. Although solution mixing is a simple operation taking the advantage of hydrophilicity of MXene nanomaterials, a few serious drawbacks such as the generation of inordinate amount of environmental wastes, poor mechanical properties associated with the ensued composites as well as the laborious evaporation of solvents usually constrain the use of solution mixing.…”

Mechanical, Thermal, and Rheological Properties of Ti3C2Tx MXene/ Thermoplastic Polyurethane Nanocomposites

“…Besides, surface treatment of MXene for polymeric nanocomposites with improved mechanical, flame retardant, and electromagnetic shielding properties by various approaches has been developed. [ 15–20 ] Yu et al. [ 17 ] modified the exfoliated Ti3C2 in aqueous solution by using two kinds of cationic modifiers, i.e., cetyltrimethyl ammonium bromide and tetrabutyl phosphine chloride, and studied fire safety properties and flame‐retardant mechanism of MXene/TPU nanocomposites.…”

Synergistic Effects of Two-Dimensional MXene and Ammonium Polyphosphate on Enhancing the Fire Safety of Polyvinyl Alcohol Composite Aerogels

“…Obviously, although the addition of a single MXene or modified MXene can reduce the PHRR of the system, the THR is reduced slightly [13,21]. MXene/chitosan nanocoating is conductive to suppressing the release of heat and smoke in TPU via the layer-by-layer (LbL) approach, but there is drawback in the complex manipulation [22].…”