Thermally Robust Hexagonally Perforated Lamellae Enabled by Asymmetric Bottlebrush Copolymers

Hexagonally perforated lamellae (HPL) via self-assembly of block copolymers (BCPs) represent one of the most sought-after nanostructures for advanced applications, yet their practical implementation has remained elusive due to their inherent metastability in conventional linear BCPs. Here, we demonstrate a paradigm shift in HPL phase stability by introducing asymmetric bottlebrush block copolymers (BBCPs) with engineered architectural and conformational asymmetries. This molecular design strategy fundamentally eliminates the chain packing frustrations that have historically plagued HPL phases, yielding the stable HPL phases in bulk materials. Our approach achieves an unprecedented composition window and exceptional thermal stability up to 300°C without order-to-disorder transitions. Dissipative particle dynamics (DPD) simulations reveal that the synergy between backbone semi-rigidity and asymmetric side chain lengths drives this remarkable stabilization. By transforming HPL phases from metastable phases into robust, readily accessible nanomaterials, this work opens new opportunities for their deployment in high-performance photonic crystals, selective separation membranes, and mechanical metamaterials.