Inkjet Printed Photonic Cellulose Nanocrystal Patterns.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Cellulose nanocrystals (CNCs) are promising for photonic inks due to their self-assembly into colored films.
• Rapid evaporation of CNC drops leads to coffee-stain morphology and weak coloration, limiting applications.
• Existing methods struggle with scalable, high-quality photonic coating production.

Purpose of the Study:

• To develop a method for producing vibrant, tunable, and scalable photonic coatings using CNCs.
• To overcome the limitations of rapid evaporation in sessile CNC drops for inkjet printing.
• To enable the creation of complex optical patterns and stimuli-responsive materials.

Main Methods:

• Inkjet printing of CNC drops through an immiscible oil layer to inhibit evaporation.
• Tuning color by controlling initial drop composition and overprinting/coalescence of different inks.
• Incorporating degradable additives to impart stimuli-responsive properties.

Main Results:

• Inhibition of water loss, reduced internal mass flow, and extended time for cholesteric self-assembly.
• Production of multicolored patterns with angle-dependent color and polarization-selective reflection.
• Demonstration of stimuli-responsive (UV light, polar solvent) photonic arrays.

Conclusions:

• Inkjet printing CNCs through an oil layer is an effective strategy for high-quality photonic coatings.
• This technique allows for on-demand color tuning and the creation of complex optical functionalities.
• The developed photonic CNC arrays are suitable for smart colorimetric labeling and optical anticounterfeiting.