Temperature-Triggered/Switchable Thermal Conductivity of Epoxy Resins.

Area of Science:

• Materials Science
• Polymer Chemistry
• Thermal Engineering

Background:

• Polymers possess low thermal conductivity (0.1-0.2 W m^-1 K^-1), limiting their use in high-power microelectronics.
• Increasing polymer thermal conductivity is crucial for advanced thermal management solutions.
• Two primary strategies include incorporating inorganic fillers or utilizing π-π stacking of aromatic units.

Purpose of the Study:

• To investigate and compare two strategies for enhancing polymer thermal conductivity.
• To evaluate epoxy-amine resins based on bisphenol A diglycidyl ether (BADGE) and 1,2,7,8-diepoxyoctane (DEO).
• To explore the role of π-π stacking and inorganic fillers in thermal performance.

Main Methods:

• Curing epoxy-amine resins using mixtures of isophorone diamine (IPDA) and o-dianisidine (DAN).
• Formulating resins with and without 5 wt.-% SiO₂ nanoparticles.
• Measuring thermal conductivity of the resulting polymer networks.

Main Results:

• Enhanced thermal conductivity (up to 0.4 W·m^-1·K^-1) was observed exclusively in DEO-based networks cured with DAN, without SiO₂ fillers.
• The improvement is attributed to π-π stacking of aromatic units in DAN, facilitated by DEO's flexible aliphatic chain.
• Enhanced conductivity was observed above the glass-transition temperature and only in the absence of inorganic fillers.

Conclusions:

• Bisphenol-free epoxy-amine resins derived from natural resources show superior thermal conductivity compared to petrol-based, bisphenol-containing resins.
• π-π stacking is a viable strategy for enhancing polymer thermal conductivity, particularly in systems without inorganic fillers.
• The findings offer a pathway to developing advanced insulating materials for microelectronic applications.