Templated Assembly of Block Copolymer toward Nonequilibrium Nanostructures in Thin Films

We report a simple route to generate nonequilibrium nanostructures combining two known block copolymer (BCP) morphologies by first templating the spatial arrangement of BCP in thin films using a supramolecule. The BCP subsequently assembles within the morphological framework established by the supramolecule, leading to a templated, nonequilibrium nanostructures not accessible by the BCP alone. Thin Films with hexagonally packed cylindrical domains oriented normal to the surface were formed initially by the self-assembly of the diblock copolymer-based supramolecules, comprised of symmetric polystyrene-b-poly-(4-vinylpyridine) (PS-b-P4VP) with 3-pentadecylphenol (PDP) hydrogen-bonded to the 4VP. After selective removal of similar to 90% of the PDP and a brief solvent annealing in a chloroform atmosphere, symmetric PS-b-P4VP, containing a trace amount of PDP, self-assembled forming polygonal (dominantly hexagonal) microdomains oriented normal to the surface. This process reported should c applicable to the large library of copolymer-based supramolecules and enables the generation of novel nonequilibrium nanostructured morphologies. It also provides a new platform to study the pathway-dependent self-assembly in polymer thin films.