Ultrasonically Assisted Green Exfoliation of Boron Nitride Nanosheets via Konjac Glucomannan for High‐Performance Thermally Conductive Interface Composites

ABSTRACT The effective exfoliation of hexagonal boron nitride and uniform dispersion of boron nitride nanosheets (BNNS) in polymer matrices remain critical challenges for enhancing the thermal conductivity of thermal interface materials. In this study, natural konjac glucomannan (KGM) biopolymer was employed for the first time to facilitate ultrasonic exfoliation of BNNS, achieving concurrent high‐efficiency exfoliation and in situ surface modification. This method presents a simple, environmentally benign, and efficient approach, serving as a sustainable alternative to conventional organic solvent‐assisted liquid‐phase exfoliation techniques. The stable BNNS/KGM dispersion underwent vacuum filtration followed by hot alkaline gelation to fabricate flexible thermally conductive composite films. The inherent hot alkaline gelation characteristics of KGM significantly streamlined the film fabrication process. Within the composite structure, BNNS exhibited an ordered lamellar stacking morphology with in‐plane orientation, which substantially improved the thermal conduction pathways. At BNNS loadings of 33 wt% and 50 wt%, the composites demonstrated exceptional in‐plane thermal conductivities of 9.80 and 12.14 W m −1 K −1 , respectively, showing outstanding thermal management capabilities in practical device testing. This work not only expands the innovation application of KGM in thermally conductive composites but also gives a novel selection for nanoparticle preparation through bio‐based surface modification strategies.