High-strength and thermally conductive bacterial cellulose-based composites via the synergy of aligned nanosheets and interfacial interactions.

Polymer-based thermally conductive composites hold great promise for thermal management in miniaturized and high-power-density electronics. However, their practical performance remains limited by discontinuous heat-transport pathways arising from the poor orientation of thermally conductive nanofillers and weak polymer-filler interfacial interactions. Here, we develop an in situ biosynthesis strategy to fabricate high-strength and thermally conductive bacterial cellulose-based nanocomposites by integrating modified nanosheets into the bacterial cellulose growth process. The growing bacterial cellulose nanofibrillar network confines and preliminarily organizes the nanosheets through polydopamine-enhanced interfacial interactions, while subsequent drying-induced compaction further improves their in-plane orientation, resulting in an integrated polymer/nanosheet architecture with continuous heat-transport pathways. The resulting composites achieve a tensile strength of 444.0 ± 19.4 MPa and an in-plane thermal conductivity of 25.24 ± 0.15 W m-1 K-1. Quantitative analysis reveals that aligned nanosheets and strong interfacial interactions are essential for the simultaneous enhancement of mechanical robustness and thermal conductivity. This work offers a bio-enabled strategy for designing advanced bacterial cellulose-based composites.