Preparation And Applications Of Quasi-Amorphous Structural Color Materials Based On Sulfur-Containing Microspheres

The quasi-amorphous structures with long-range disordered and short-range ordered microsphere arrays possess unique optical properties.Artificial construction of quasi-amorphous structures is an important approach for obtaining noniridescent structural colors,and shows great potential for practical applications in paints,decoration,textile coloring,anticounterfeiting,and other color-related fields.However,incoherent light scattering and point contact among microspheres lead to the defects of color visibility and structural stability respectively,which are the core problems of restricting the practical application of quasi-amorphous structures.In view of the above problems,quasi-amorphous structural color composites with structural stability were designed in this paper.Sulfur-containing microspheres with optical absorption properties and adhesives were assembled together on the applied substrates,achieving the multicolor output of noniridescent structural colors with high color visibility and excellent structural stability.Through hot pressing,quasi-amorphous structures were confined by thermoplastic films to prepare the quasi-amorphous structural color composite films with mechanical toughness and flexibility.In this strategy,trilayer quasi-amorphous heterostructure was confined to make portable encryption composites,which can realize the hiding and displaying of information.The quasi-amorphous structural color coatings were facilely fabricated by spraying the polysulfide microsphere(PSFM)with optical absorption properties and synthesized waterborne polyurea(WPU)with small particle size.Color visibility of quasi-amorphous structures was significantly improved because of the optical absorption properties and high refractive index of PSFM.To enhance the structural stability,WPU with low glass transition temperature was used as an adhesive and can be filled in the gaps among PSFM to achieve structural locking after assembly.Rapid patterning was realized on various substrates through a simple mask-spraying process,which not only enabled excellent fastness performance but also can be prepared on the bulk scale.The strategy of thermal-guided interfacial confinement was designed based on the thermal machinability of thermoplastics,and patterned quasi-amorphous structures of sulfur-containing thiodiphenol-formaldehyde microspheres(TPFM)were confined between two layers of super-adhered thermoplastic films to prepare flexible quasi-amorphous structural color composite films.TPFM with excellent thermal properties can maintain spherical morphology during hot pressing process.The composites after molding possessed excellent mechanical strength and high color visibility.Trilayer quasi-amorphous heterostructure of polystyrene microspheres(PSM)/TPFM/PSM was confined between thermoplastic polyurethane(TPU)films to prepare encryption composites.The upper and bottom PSM layers enabled the optical shielding of the TPFM encrypted layer under normal conditions.Based on the difference of thermal stability between PSM and TPFM,the PSM layers turned to transparent during high-temperature decoding,showing the encryption pattern of TPFM.Meanwhile,the encryption strategy is convenient and imperceptible,and the product is easy to carry.Therefore,it has great application value in the field of information security.