Small Organic Linkers with Hybrid Terminal Groups Drive Efficient Phonon Transport in Polymers

In traditional polymer composites, past studies have shown that employing hybrid filler led to the enhanced thermal conductivity due to the synergistic impact of the filler combination. Such traditional composites, although extensively used, suffer from various mechanical and processing issues. We have demonstrated how by employing organic molecule with hybrid terminal groups resulted in enhanced thermal conductivity compared with the bulk polymer. The highest thermal conductivity of 0.55 W/m·K was achieved when organic molecule with hybrid terminal groups was incorporated in base polymer. Engineering intermolecular interaction helps to create a continuous thermal network that facilitates phonon transport. The hybrid thermal bridges created with the base polymer act as a synergistic center that further boosts phonon transport. Interestingly, such thermal conductivity enhancement with hybrid terminal groups was found in both amorphous and crystalline organic molecules. Along with good thermal conduction, such films are optically transparent, too, which adds significant commercial and aesthetic value at the same time free of undue processing and mechanical issues that generally result from polymer composites reinforced with traditional metallic, carbonic, and ceramic fillers. Another interesting particularity noticed was the inverse relationship between thermal conductivity and crystallinity. Composite with hybrid groups with various contributing factors like increased intermolecular interaction, polymer chain confinement, influence of crystals, reduced interfacial thermal resistance, and so on is proposed to create a synergistic impact that ultimately leads to enhanced thermal conduction. Such materials can be used for the development of the thermal management system for efficient heat dissipation.