Polydopamine-Modified Al₂O₃/Polyurethane Composites with Largely Improved Thermal and Mechanical Properties

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Polyurethane (PU) is a versatile polymer, but its application as a thermal interface material (TIM) is limited by its inherent thermal and mechanical properties.
• Alumina (Al2O3) is a ceramic filler with high thermal conductivity, but its poor dispersion in polymer matrices hinders effective property enhancement.

Purpose of the Study:

• To develop enhanced alumina/polyurethane composites for improved thermal interface material applications.
• To investigate the effect of polydopamine (PDA) surface modification on alumina particles for better dispersion and property enhancement in a PU matrix.

Main Methods:

• In situ polymerization was used to prepare alumina/polyurethane composites.
• Alumina particle surfaces were modified with polydopamine (PDA).
• Characterization techniques included FTIR, TG, Raman spectroscopy, SEM, and DMA.

Main Results:

• SEM images confirmed improved dispersion of PDA-modified alumina (PDA-Al2O3) in the PU matrix compared to unmodified alumina.
• The 30 wt% PDA-Al2O3/PU composite exhibited significant improvements: 95% increase in Young's modulus, 128% in tensile strength, and 76% in elongation at break.
• Dynamic mechanical analysis showed enhanced storage modulus and a higher glass transition temperature (Tg). Thermal conductivity increased by 138%.

Conclusions:

• Polydopamine surface modification of alumina is an effective strategy to improve its dispersion in polyurethane.
• The PDA-Al2O3/PU composites demonstrate simultaneous enhancements in mechanical properties (modulus, strength, elongation) and thermal conductivity.
• These findings highlight the potential of PDA-coated alumina as a filler for advanced thermal interface materials.