Exploring the Multifunctional Applications of Surface-Coated Polymeric Foams─A Review

Polymeric foams are porous, lightweight, and low-cost materials. Traditionally, polymeric foams have been used in home appliances, automotive, construction, transportation, and aerospace. However, the modern advancements and the materials demand have fostered the expansion of the application realm of these foams to other technological areas encompassing energy storage devices and Li-ion batteries, piezoresistive sensors, biomedical scaffolds, oil–water separation and water remediation etc., through coating. The sustainable technological solutions of these low-cost foams have now been realized through mutual attributes of their properties (high surface area, open-cell, low density, and flexibility), the availability of numerous advanced materials (e.g., carbon nanotubes, graphenes and metal oxide nanoparticles), and versatile and innovative coating methods. In this review, we discuss the recent progress in coating techniques of various polymeric foams by surface treatments and their applications. The surface modification of widely used and the most studied thermoset foams, namely, flexible polyurethane, melamine formaldehyde foams, thermoplastic foams such as polypropylene and ethylene vinylene acetate, and polystyrene foams are considered with special emphasis on open-cell foams. Further, hydrophobic coatings which have a large implication in environment cleanup and oil adsorption are highlighted. The use of a wide spectrum of nanoparticles, polymers, and organic compounds as coating materials is investigated. How the inherent properties such as hydrophobicity, adsorption capability, electrical and thermal conductivities, fire retardancy, electromagnetic interference shielding, and biocompatibility of the foam are influenced through modification is explicitly discussed. The methods which have used the modified foam as a support for catalysis and electrodes in Li-ion batteries are also deliberated. The properties of these coated substrates have been found to rely on the coating material, efficacy of the coating method, and the surface properties. Lastly, practical challenges of these foams in large scale use and future prospects in environment cleanup and energy storage have been envisioned.