Controllable hydrophilic/superhydrophobic patterned coatings for optical information encryption/decryption based on water-triggered opaque to translucent transition

• Published in: Journal of colloid and interface science 2024-01, Vol.654, p.764-773
• Main Authors: Su, Xiaojing, Li, Kunquan, Xie, Huali, Chen, Zhuohan, Li, Xuanjun, Wu, Wenjian
• Format: Article
• Language: English
• Subjects: air; contact angle; Encryption/decryption; heat; Hydrophilic/superhydrophobic patterns; hydrophilicity; hydrophobicity; methodology; microstructure; Optical information; refractive index; roughness; Transparency transition; Water-triggered
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2023.10.093

[Display omitted] •A controllable hydrophilic/superhydrophobic patterned coating is reported.•The superhydrophobic pattern presents rough ridge-like microstructures and opaque state.•The hydrophilic pattern exhibits water-triggered opaque to translucent transition.•The patterned coating is successfully applied in optical information encryption/decryption.•The information revealing demonstrates long-term stability and great reusability. Anti-counterfeiting technologies are crucial for securing the authenticity and proof of commodities, in which the optical information encryption/decryption has attracted extensive attention for its overriding advantages of visibility and convenience. Inspired by the unique transparency transformation phenomenon of Diphylleia grayi petals, a controllable hydrophilic/superhydrophobic patterned coating with water-triggered opaque to translucent transition is proposed through the construction of a superhydrophobic coating, subsequent air plasma etching under a mask, and final hydrophilic modification to introduce stable invisible patterns. The superhydrophobic region exhibits great water repellency with a water contact angle (WCA) at 157°, while the hydrophilic region quickly absorbs water with a WCA at 61°. The patterned coating presents an opaque state for the serious light scattering induced by the rough microstructure and large refractive index difference between the coating and air, while the hydrophilic patterns on the coating transform to translucent after water infiltration for the reduced roughness and close refractive indexes of the coating and water. The information revealing is rapid and reversible, and demonstrates heat and long-term stability and great reusability. The findings conceivably stand out as a new methodology to fabricate controllable superwettable coatings with optical information encryption/decryption capability for application in anti-counterfeiting.