MXene-coated polystyrene microparticles for amorphous photonic crystal coating with enhanced color saturation, flame retardancy, and electromagnetic interference shielding

To enhance the color saturation of the amorphous photonic crystal (APC) coating composed of polystyrene (PS) microparticles, MXene nanosheets were deposited on the surface of the PS microparticles through strong electrostatic attraction. Three distinct colored APC coatings were achieved using Mayer rod-coating methods, employing PS microparticles of varying sizes. The intrinsic black nature of MXenes results in these coatings exhibiting high brightness of structural colors under ambient lighting conditions. Additionally, the three distinct colored APC coatings demonstrate high color saturation and low angular dependence. The thermal stability and flame retardancy of PS and PS@MXene microparticles with different MXene content were investigated. PS@MXene microparticles (three different diameters) containing 5 wt% MXene exhibited char residues of 11.0, 8.7, and 6.7 wt% at 700 °C during decomposition, whereas pure PS microparticles showed a char residue of <1.7 wt%. The peak heat release rate and total heat release of the PS@MXene microparticles were lower than those of pure PS, as characterized by a microscale combustion calorimeter. Furthermore, crack-free APC coatings on a black polyurethane substrate were successfully prepared using the Mayer rod-coating method, assisted by polyacrylic acid and ethylene glycol. The APC coatings containing PS@MXene microparticles with 5 wt% MXene, deposited on the surface of the polyurethane film, demonstrated shielding performances of approximately 20 dB. This work presents a straightforward and environmentally friendly method for constructing multifunctional APC coatings.