Microphase Separation Promoting High-Temperature Energy Storage Properties of Polymer Alloys

Area of Science:

• Materials Science
• Polymer Science
• Electrical Engineering

Background:

• High-temperature polymer dielectrics are crucial for modern power electronics.
• Polyetherimide (PEI) shows promise but suffers from high conductive loss at elevated temperatures, limiting its energy storage density.
• Developing materials that maintain dielectric performance under harsh conditions is essential.

Purpose of the Study:

• To design a polymer alloy that overcomes the limitations of pure PEI for high-temperature dielectric applications.
• To improve the energy storage density and efficiency of polymer dielectrics at high temperatures.
• To investigate the role of intermolecular hydrogen bonding and nanoconfinement in enhancing material properties.

Main Methods:

• A polymer alloy was synthesized by combining polyetherimide (PEI) with semi-aromatic benzimidazole polyimide (SPBII).
• Intermolecular hydrogen bonding was utilized to stabilize a nanoscale microphase-separated structure.
• The effects of SPBII incorporation on thermal, mechanical, and electrical properties, including conductive loss and breakdown strength, were evaluated.

Main Results:

• The PEI/SPBII alloy exhibited enhanced thermal and mechanical properties, with a glass transition temperature (T_g) of 287.5°C and Young's modulus of 5.32 GPa for the 50% SPBII composition.
• Charge traps at the PEI/SPBII interface effectively suppressed high-temperature conduction loss.
• At 200°C, the 50% SPBII alloy achieved an energy density of 4.53 J cm^-3 with 90% efficiency, significantly outperforming pure PEI (1.71 J cm^-3).

Conclusions:

• The developed PEI/SPBII polymer alloy demonstrates superior capacitive performance under high-temperature conditions.
• The combination of nanoconfinement and interface engineering effectively mitigates conductive loss in polymer dielectrics.
• This research offers a promising pathway for advancing polyimide-based dielectric materials in demanding power electronic applications.