Moisture driven thermal conduction in polymer and polymer blends

Though lots of work is available in thermally conductive filler-polymer composite, clear understanding of the heat conduction mechanism in neat polymers or polymer blends is a subject of great investigation especially for the promotion and development of new thermal management technologies. This study shows an interesting tale of intermolecular interaction in governing thermal conduction in polymers and how the quality of “thermal connections” through intermolecular interactions like hydrogen bonding can effectively drive heat propagation in polymers. Here by engineering intermolecular interaction through hydrogen bonding in polymer chains, a significant enhancement in thermal conductivity was achieved and corresponding decrement was observed by breaking those interactions. Thermal conductivity of free standing PVA films with different molecular weights and its blends with PEG and PVP was investigated. Effect of the absorption of vapor molecules of water, ethanol, methanol and ethylene diamine on polymer film's thermal conductivity was studied. Penetration of water molecule in films was found to drastically alter inter-molecular interaction contributing to remarkable 200% increment in thermal conductivity. Thermal conduction of polymer blends with varied intermolecular interactions was further explored. Neat PVA films with lower molecular weight had higher thermal conductivity due to less dense and hindered polymer chains and ease of interaction to form continuous thermal network. This study unveils some of the important yet fascinating drivers of thermal conductivity in polymers & polymer blends which can pave the way for development and fabrication of polymer based materials for thermal management applications.