Flame-Retardant and Self-Healing Waterborne Polyurethane Based on Organic Selenium

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Waterborne polyurethanes (WPUs) are environmentally friendly but struggle to combine flame retardancy, self-healing, and mechanical strength.
• Achieving these properties simultaneously is challenging due to their often-contradictory nature.

Purpose of the Study:

• To synthesize novel WPUs with integrated flame retardancy and self-healing capabilities.
• To investigate the role of organic selenium in imparting these dual functionalities.

Main Methods:

• Synthesis of WPUs with varying organic selenium content (SWPU-x).
• Evaluation of flame retardancy using vertical combustion tests and limiting oxygen index (LOI).
• Assessment of self-healing efficiency under room temperature conditions and mechanical property testing.

Main Results:

• SWPU-x films demonstrated rapid self-extinguishing behavior (<1 s) and improved LOI (up to 28.5%, UL-94 V-0).
• High self-healing efficiency (91.25%) was achieved after 30 min of room-temperature photoreactor treatment.
• Excellent mechanical properties were maintained (18.5 MPa tensile strength, 869.63% elongation at break).
• Total heat release was significantly reduced (to 23.80% of the original WPU).

Conclusions:

• Organic selenium incorporation effectively enables simultaneous flame retardancy and self-healing in WPUs.
• The diselenide dynamic bond and free radical scavenging contribute to the observed properties.
• These findings open new avenues for developing high-performance, safe, and repairable waterborne polyurethane materials.