High-Security Plastic with Integrated Holographic and Phosphorescent Images

Area of Science:

• Materials Science
• Polymer Chemistry
• Optics

Background:

• Organic room temperature phosphorescence (ORTP) polymer materials show promise but have limited optical functions for multi-mode imaging.
• Existing ORTP materials lack integrated holographic capabilities.

Purpose of the Study:

• To develop a universal approach for imparting periodic refractive index modulation functions to ORTP polymer materials using holographic patterning.
• To enhance the optical functionalities of ORTP materials for advanced applications.

Main Methods:

• A two-stage stepwise crosslinking strategy was designed for ORTP polymer materials.
• Stage-1 involved low crosslinking density for monomer diffusion and holographic patterning via photopolymerization-induced phase separation.
• Stage-2 involved dense crosslinking to activate and enhance phosphorescence.

Main Results:

• The holographic patterning successfully endowed ORTP materials with periodic refractive index modulation.
• Phosphorescence intensity increased by 144% with increased crosslinking density in stage-2.
• Theoretical calculations indicated enhanced phosphorescence due to increased conformational distortion and spin-orbit coupling.

Conclusions:

• A novel method was demonstrated for creating holographic ORTP polymer materials with independent holographic and phosphorescent image display.
• This work offers a new paradigm for adding optical functions to ORTP materials.
• The developed materials show potential for high-security optical applications, including anti-counterfeiting.