Engineering molecular interaction in polymeric hybrids: Effect of thermal linker and polymer chain structure on thermal conduction

In past decades, more research efforts have been devoted to the processing of thermally conductive polymer composite and less on fundamental aspects of heat conduction in polymeric materials. Here we presented a polymeric hybrid system comprising of polymer chain and short thermal linkers that show promising thermal conductivity and optical transparency. This was achieved by engineering their intermolecular interactions without incorporating traditional fillers (carbon, ceramic and metal). Polyvinyl alcohol (PVA) with different degrees of hydrolysis has been engineered to achieve enhanced thermal conduction by using small organic linkers (OL) having symmetric terminal groups such as ethylene diamine (ED) and ethylene glycol (EG) and hybrid terminal groups like ethanolamine (EA). Comparing with ED and EG, EA has been demonstrated more effective in enhancing thermal conductivity for both PVAs with different degrees of hydrolysis (88% and 99+%). Presence of bulkier acetate group in PVA (88% hydrolysis) restricted the efficient thermal connections by steric hindrance. Optimized pairing of terminal groups of OLs was thus found to provide an interesting handle to manipulate the thermal conductivity. Additionally, degree of hydrolysis of polymer matrix is another crucial factor to effectively engineer thermal conductivity. In summary, impact of functional group, molecular structure, side groups of backbone polymer and organic linkers were found to have substantial impact on overall thermal conductivity of PVA/OL and can be manipulated for efficient thermal management.