Boosting thermal conductivity of boron nitride incorporated polymer composites via hydrogen bonding engineering.

Enhancing the thermal conductivity of polymer-based composites is critical for effective thermal management in power electronics. A common strategy involves incorporating high-thermal-conductivity fillers such as graphene and boron nitride nanosheets (BNNS). However, practical enhancements often fall short of theoretical predictions due to interfacial thermal resistance (RKapitza). Here, we address this challenge by engineering the hydrogen bond density (HBD) at the filler-matrix interface. By grafting 3,4-dihydroxyphenylalanine (DOPA) onto polyvinyl alcohol (PVA), we synthesized PVA-DX matrices (X = 0, 8, 12, 17, 24) with tunable HBDs. Incorporation of BNNS into these matrices revealed that higher interfacial HBD significantly reduces RKapitza, thereby enhancing the composite's thermal conductivity (κc). We achieved an exceptionally low RKapitza of 0.60 × 10-8 m2 K W-1, corresponding to a filler effectiveness (κc/∅f) of 120 W m-1 K-1. Notably, at a BNNS loading of 70 vol%, increasing the interfacial HBD to 2.14 mmol cm-3 achieves a κc of 51.01 W m-1 K-1, which is 1.45 times higher than the 35.29 W m-1 K-1 attained at an HBD of 0.5 mmol cm-3. This study underscores the critical role of interfacial hydrogen bonding in optimizing thermal transport and provides a robust framework for designing high-performance polymer composites for advanced thermal management applications.