Nonconventional Full-Color Luminescent Polyurethanes: Luminescence Mechanism at the Molecular Orbital Level

Area of Science:

• Materials Science
• Polymer Chemistry
• Luminescence

Background:

• Structure-activity relationships are crucial for developing novel luminescent materials.
• Nonconjugated polymers offer unique optical properties distinct from traditional conjugated systems.
• Understanding the molecular basis of luminescence in polymers is essential for material design.

Purpose of the Study:

• To develop a general protocol for synthesizing nonconjugated polyurethanes (PUs) with full-color emission.
• To investigate the influence of unsaturated bonds and hydrogen bonding on PU luminescence.
• To explore the structure-property relationships governing the luminescence mechanisms of these PUs.

Main Methods:

• Synthesis of nonconjugated polyurethanes (PUs) by controlling diol monomer structure and polymerization conditions.
• Introduction of single, double, or triple bond repeating units into the polymer backbone.
• Experimental and theoretical analysis, including molecular orbital calculations, to study luminescence properties and temperature-dependent behavior.

Main Results:

• Achieved easily tunable full-color (red, green, blue) emission in nonconjugated PUs.
• Demonstrated that unsaturated bonds and hydrogen bonding significantly impact luminescence.
• Observed distinct temperature-dependent behaviors attributed to H-bonding, n-π interactions, and aggregation.

Conclusions:

• A new, general protocol for preparing multifunctional nonconventional fluorescent polymers was established.
• The study deepens the understanding of luminescence mechanisms in nonconjugated polymers.
• The developed PUs show potential for applications in colorful displays, covert information transmission, and multifunctional bioimaging.