Synergistic Flame Retardant Effects of Carbon Nanotube‐Based Multilayer Nanocoatings

Abstract

In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers.

Synergistic Combination of Dual Clays in Multilayered Nanocomposites for Enhanced Flame Retardant Properties

“…The multilayer structure and interlayer spacing of clay nanoplatelets were further investigated using an XRD scan (Figure c). The XRD pattern of neat MMT exhibited a (001) diffraction peak at 2θ = 7.18 ○ which is assigned to the d 001 of 1.23 nm . The bare VMT powder displayed the specific diffraction peaks at 2θ = 6.22 ○ (d = 1.42 nm), 7.12 ○ (d = 1.24 nm), and 7.48 ○ (d = 1.18 nm), indicating the presence of one or two water layer hydration states in the interstratified phases. − The reflection peak at 8.79 ○ (d = 1.01 nm) can be attributed to the existence of mica phases .…”

Asymmetric Multienergy-Coupled Radiative Warming Textiles for Personal Thermal-Moisture Management

“…In addition, Figure S17 shows that Janus fabric cannot burn within 120 s of exposure to the flame. The existence of copper and CNT could synergistically improve the flame retardancy of Janus fabric, endowing the textile with potential applications in environments with fire hazards . The current stability was evaluated by repeatedly applying/closing the voltage cycle test 200 times in order to investigate the voltage resistance and oxidation resistance of the Janus fabric.…”

Fireproof Nanocomposite Polyurethane Foams: A Review

“…Since pure nanotubes cannot provide proper flame retardancy of the final nanocomposites, CNTs are usually applied as a component of CFRs. Taking into account the negative charge of CNT surface and a great number of CNT surface modification approaches, the LbL technique seems to be the best option for PUF modification [ 57 , 67 , 68 , 69 ]. It should be noted that the LbL technique can create multilayer coatings on a charged substrate which is alternatively immersed into positively and negatively charged species.…”

“…Thus, for instance, aqueous CNT suspensions stabilized by using polyacrylic acid (PAA) and montmorillonite (MMT) were utilized as a component of bilayer (BL) coatings of flexible PUFs in [ 67 , 68 ]. In some cases, CNTs are modified/grafted for better interaction with other layers [ 57 , 69 ].…”