Leveraging Zone Annealing to Navigate the Coassembly Pathway of High-Loading Nanorods in Block Copolymers for Enhanced Thermal Transport

Achieving long-range ordered ensembles of nanorods at high loading is crucial for the development of thermally conductive polymer nanocomposites, but it remains challenging due to serious thermodynamic and kinetic constraints. In this regard, we propose the zone annealing protocol as a kinetically regulated strategy to navigate the coassembly pathway of binary nanorods within block copolymer templates through synergistically tuning the composition of the nanorods. The integrated multiscale model reveals that a symmetric composition of the binary nanorods enables a cooperative incorporation mechanism of zone annealing, which more effectively redistributes steric constraints of internanorods and suppresses kinetic arrest of nanoscale defects. Accordingly, the block copolymer nanocomposites under the zone annealing can achieve well-ordered nanostructures with interface-parallel alignment of nanorods. The optimized nanostructures enable a significant enhancement in the effective thermal conductivity along the alignment direction of nanorods by creating efficient phonon pathways, yielding a pronounced anisotropy of the thermal transport. This work establishes the zone annealing protocol to direct the coassembly pathway of block copolymer nanocomposites and offers a promising design principle for realizing the good alignment of nanorod ensembles with directional thermal transport.