Uniform Single-Domain Liquid Crystalline Hexagonal Rods by Synchronized Polymerization and Self-Assembly Using...

Area of Science:

• Materials Science
• Organic Chemistry
• Nanotechnology

Background:

• Polycyclic aromatic hydrocarbons (PAHs) offer attractive optical, electrical, and magnetic properties for nanostructure fabrication.
• Achieving uniform and well-defined PAH nanostructures via self-assembly remains a significant challenge in materials science.

Purpose of the Study:

• To develop a method for fabricating uniform nanostructures from triphenylene (TP)-derived monomers.
• To investigate the mechanism and key factors governing synchronized polymerization and self-assembly (SPSA) in PAHs.
• To explore the photophysical properties of the resulting PAH nanostructures.

Main Methods:

• Utilized synchronized polymerization and self-assembly (SPSA) to synthesize triphenylene (TP)-derived monomers.
• Characterized the morphology and structure of the self-assembled nanostructures, focusing on hexagonal rods.
• Analyzed the influence of temperature on the SPSA process and identified an upper critical temperature.
• Investigated the photoluminescence properties, including fluorescence and phosphorescence, of the nanostructures.

Main Results:

• Successfully fabricated highly uniform hexagonal rods from TP-derived monomers using SPSA.
• Demonstrated that the length/diameter ratios of the rods are tunable over a wide range.
• Clarified the formation mechanism of SPSA, identifying an upper critical temperature linked to microphase separation.
• Observed simultaneous fluorescence and phosphorescence emission at room temperature due to columnar stacking of TP units.

Conclusions:

• SPSA is an effective strategy for creating uniform PAH nanostructures with controlled dimensions.
• The identified upper critical temperature and microphase separation principle are crucial for successful SPSA.
• The columnar stacking in TP nanostructures enhances intersystem crossing, leading to dual light emission, offering potential for advanced optoelectronic applications.