Enabling Flexible and Tunable Structural Color Films Based on Rapid Ethanol-Induced Nanosphere Rearrangement for Anti-Counterfeiting and Dynamic Marking

Structural colors epitomize a profound relationship where optical precision and architectural finesse converge in the emission of unfathomable iridescent shades, transcending the limitations of traditional pigmentation. Fueled by prodigious applications in flexible displays, intelligent sensing, and anticounterfeit labels, structural color materials emerge superior. The swift production of colors enabled by straightforward solvent-mediated dynamic self-assembly represents a peak achievement in contemporary research. Poly(NIPAm-<i>co-t</i>BA) (PNTs) demonstrated strong thermo-sensitivity and their ordered arrays exhibited structural color. A three-dimensional (3D) "blackberry-like" aggregation was formed using PNTs and polyacrylamide (PAAm) via colloidal electrospinning. These fibers rapidly dissolve in a 75% ethanol-water mixture, allowing nanospheres to self-organize into two-dimensional (2D) arrays in 2 min. Spectrogram analysis shows that samples subjected to a 75% ethanol-water mixture exhibit remarkable reflectivity. By varying the size of nanospheres, the PNTs/PAAm mass ratio, and electrospinning time, structural colors were controlled from red (670 nm) to blue (327 nm), demonstrating effectiveness for anti-counterfeiting and dynamic marking applications.