High thermal conductivity biphenyl-type polyester with photochromism, thermo-responsive, and shape memory performance

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Stimuli-responsive materials are crucial for advanced applications like anti-counterfeiting and thermal management.
• High thermal conductivity polymers are sought after for efficient heat dissipation.
• Photochromic polymers offer dynamic optical properties for smart devices.

Purpose of the Study:

• To synthesize and characterize novel high thermal conductivity polyesters (HPE1 and HPE2).
• To investigate the photochromic behavior and underlying mechanisms of HPE2.
• To evaluate the thermal conductivity and shape memory properties of HPE2.

Main Methods:

• Melt polycondensation for polyester synthesis.
• UV-Vis and fluorescence spectroscopy to study photochromism.
• Density Functional Theory (DFT) calculations for mechanism elucidation.
• Thermal conductivity measurements (in-plane and through-plane).
• Shape memory property testing.

Main Results:

• HPE2 exhibits reversible photochromism (brown to yellow under UV light) due to charge transfer interactions.
• The polymer's structure, with alternating donor-acceptor units, promotes ordered microstructure via π-π stacking.
• HPE2 film shows high in-plane thermal conductivity (0.67 W/(m·K)), significantly exceeding PET.
• Reversible thermal response allows switching between high (0.27 W/(m·K)) and low (0.17 W/(m·K)) through-plane thermal conductivity states.
• Excellent shape memory properties were observed with high shape fixed (99%) and recovery (86%) ratios.

Conclusions:

• The synthesized HPE2 demonstrates a unique combination of photochromic, high thermal conductivity, and shape memory properties.
• The material's responsiveness to light and thermal stimuli opens possibilities for smart material applications.
• The structure-property relationship highlights the potential of tailored polymer design for advanced functionalities.