Room-temperature autonomous self-healing glassy polymers with hyperbranched structure.

Area of Science:

• Polymer Science
• Materials Chemistry
• Materials Engineering

Background:

• Glassy polymers typically exhibit limited self-healing capabilities below their glass transition temperature (Tg) due to molecular immobility.
• The frozen molecular structure in conventional glassy polymers hinders efficient crack repair and property restoration.

Purpose of the Study:

• To engineer randomly hyperbranched polymers (RHPs) capable of autonomous self-healing in the glassy state.
• To investigate the relationship between hyperbranched architecture, hydrogen bonding, and self-healing performance.
• To demonstrate rapid and efficient self-healing of mechanical properties at room temperature.

Main Methods:

• Fabrication of randomly hyperbranched polymers (RHPs) with a high density of hydrogen bonds.
• Characterization of polymer properties, including glass transition temperature (Tg) and storage modulus.
• Evaluation of self-healing capabilities through tensile strength recovery tests at room temperature.

Main Results:

• The synthesized RHPs possess a high glass transition temperature (up to 49 °C) and storage modulus (up to 2.7 GPa).
• The hyperbranched structure facilitates molecular mobility and enables dynamic hydrogen bond exchange in the glassy state.
• Instantaneous self-healing was achieved, with recovered tensile strength up to 5.5 MPa within 1 minute, and efficiency increased with contact time.

Conclusions:

• Randomly hyperbranched polymers with abundant hydrogen bonds can overcome the limitations of glassy polymer self-healing.
• The unique molecular architecture allows for network reconfiguration and rapid property recovery in the absence of external stimuli.
• These findings open new avenues for developing self-healing materials for demanding applications.