Self-Assembly of\nHierarchical Silicon-Containing Block\nCopolymers with Cross-Linkable 3 nm Smectic Motifs for Nanopatterning\nand Osmotic Energy Conversion Membranes

Highly-dense small-feature-size nanopatterns and nanoporous\nmembranes\nare important in advanced microelectronics, nanofiltration, and biomimic\ndevice manufacturing. Here, we report the synthesis and self-assembly\nof a series of high-interaction-parameter (high-χ) silicon-containing\nhierarchical block copolymers (BCPs) with cross-linkable subordering\nchalcone motifs, which possess both an intrinsic native etching contrast\nfor nanofabrication and cross-linkability under ultraviolet light\nfor generating free-standing membranes. BCPs with a volume fraction\nof chalcone block of 55–74% form ordered primary nanostructures\nwith period 15−22 nm including lamellae, double gyroid, hexagonally\npacked cylinders, and body-centered cubic spheres of the minority\nSi-containing block. The majority PChMA block self-assembles into\na highly ordered 3 nm smectic sublattice, and cross-linking after\nself-assembly enables the formation of free-standing isoporous membranes.\nBoth silicon oxide nanopatterns and free-standing nanoporous osmotic\nenergy conversion membranes are generated by etching films of these\nBCPs. This work demonstrates that the combination of hierarchical\nordering and cross-linkable motifs in a high-interaction parameter\nBCP enables applications in both nanofabrication and free-standing\nfunctional porous membranes.