Thermal Conductance in Cross-linked Polymers: Effects of Non-Bonding Interactions

Area of Science:

• Materials Science
• Polymer Chemistry
• Thermal Physics

Background:

• Interchain interactions are critical for heat transfer in polymers.
• Cross-linking aims to improve polymer thermal conductivity, but results are inconsistent.
• Understanding the roles of covalent and nonbonding interactions is key.

Purpose of the Study:

• Investigate heat transfer mechanisms in cross-linked polymers.
• Clarify discrepancies in previous thermal conductivity studies.
• Determine the primary mechanisms for thermal conductivity enhancement.

Main Methods:

• Examined relative contributions of bonding (covalent) and nonbonding (van der Waals, electrostatic) interactions.
• Analyzed the effect of cross-linker length on interchain distance.
• Modeled energy transfer from THz acoustic waves with and without nonbonding interactions.

Main Results:

• Short cross-linkers enhance thermal conductivity by increasing interchain proximity.
• Enhanced nonbonding interactions, dependent on interchain distance, are the primary drivers of improved heat transfer.
• Thermal conductivity increases significantly when nonbonding interactions are considered.

Conclusions:

• Cross-linker length is crucial for enhancing polymer thermal conductivity.
• Nonbonding interactions play a more significant role than covalent pathways in cross-linked polymers.
• Findings explain varied thermal conductivity trends observed in different cross-linking studies.