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.
Highlights
Polystyrene (PS) is widely used in many fields due to its low density, excellent chemical resistance, and ease of processing [1,2,3]
When etched Ti3 C2 was modified by decyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium bromide (OTAB) and dihexadecyldimethylammonium bromide (DDAB), the interlayer distance between the sheets increased per the length of the alkyl chains attached for the cationic modifiers respectively
In this work, exfoliated MXene nanosheets were successfully modified by long-chain cationic agents, i.e., DTAB, OTAB and DDAB to enhance its dispersion and interfacial adhesion in PS and simultaneously improve the thermal stability and flame retardancy, and reduce the production of toxic fumes
Summary
Polystyrene (PS) is widely used in many fields due to its low density, excellent chemical resistance, and ease of processing [1,2,3]. This method can endow flame retardancy; for instance, the peak heat release rate (PHRR) of the PS composites can be decreased (by approximately 83.6%) by adding 30 wt.%. In this work, exfoliated Ti3 C2 nanosheets were prepared by etching titanium aluminum carbide (Ti3 AlC2 ) using lithium fluoride (LiF) plus concentrated hydrochloric acid, followed by ultrasonic treatment in deionized water. These exfoliated Ti3 C2 nanosheets were modified using three kinds of long-chain cationic modifiers, i.e., decyltrimethylammonium bromide (DTAB), octadecyl trimethylammonium bromide (OTAB), and Polymers 2019, x, x FOR PEER REVIEW didodecyldimethylammonium bromide bromide (DDAB),.
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