by Sona Stanly and Honey John, Cochin University of Science and Technology.
Research shows the development of a graphene/clay hybrid which is an eco-friendly material with air purification capability, and which can also serve as a flame retardant additive in polymers.
In the past few decades, two-dimensional nanomaterials like layered silicates, graphene and layered hydroxides (LDH) have been widely studied due to their high aspect ratio, which in turn enhances properties like flame resistance, mechanical properties, gas adsorption, barrier properties and
water purification. Among the layered silicates, montmorillonite is widely accepted, not only because of its low toxicity and cost, but also for its cation exchange capability. The cations exchange with chain molecules, which in turn increases the interlayer galleries of the pristine montmorillonite (MMT) and effectively increases the dispersibility in polymer matrices, which ultimately results in property enhancement. In addition, another important type of 2D material includes carbonaceous materials like graphene, carbon nanotubes (CNT) and carbon nanofibers (CNF), among which graphene has most recently attracted a tremendous interest due to its high mechanical properties, thermal and electrical conductivity, and gas barrier property. However, its flame retardancy is not so impressive because of its weak thermo-oxidative stability.
A hybrid with clay, a 2D planar nano-material with excellent barrier property and thermal stability, will make graphene a good flame retardant material. This will then allow substitution in various polymer systems of the conventional halogenated flame retardants. The high surface area of clay and graphene, along with the presence of cations in the inter layer galleries of clay, also make the hybrid a better material for the adsorption of gases, especially carbon dioxide from air. This research work shows the development of a graphene/ clay hybrid which is an eco-friendly material with air purification capability, and can also serve as a flame retardant additive in polymers.