Hierarchical Self-Assembly of Halogen-Bonded Block Copolymer Complexes into Upright Cylindrical Domains
Milani, R.a, Houbenov, N.b, Fernandez-Palacio, F.c, Cavallo, G.c, Luzio, A.d, Haataja, J.b, Giancane, G.e, Saccone, M.f, Priimagi, A.f, Metrangolo, P.a,b,c,d, Ikkala, O.b
a VTT Technical Research Centre of Finland Ltd., Espoo, 02044 VTT, Finland
b Department of Applied Physics, HYBER Centre of Excellence, Aalto University, Espoo, 02150, Finland
c Laboratory of Nanostructured Fluorinated Materials (NFMLab), Department of Chemistry, Materials, Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, 20131, Italy
d Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Milano, 20131, Italy
e Dipartimento Beni Culturali, Università del Salento, Lecce, 73100, Italy
f Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, 33101, Finland
Self-assembly of block copolymers into well-defined, ordered arrangements of chemically distinct domains is a reliable strategy for preparing tailored nanostructures. Microphase separation results from the system, minimizing repulsive interactions between dissimilar blocks and maximizing attractive interactions between similar blocks. Supramolecular methods have also achieved this separation by introducing small-molecule additives binding specifically to one block by noncovalent interactions. Here, we use halogen bonding as a supramolecular tool that directs the hierarchical self-assembly of low-molecular-weight perfluorinated molecules and diblock copolymers. Microphase separation results in a lamellar-within-cylindrical arrangement and promotes upright cylindrical alignment in films upon rapid casting and without further annealing. Such cylindrical domains with internal lamellar self-assemblies can be cleaved by solvent treatment of bulk films, resulting in separated and segmented cylindrical micelles stabilized by halogen-bond-based supramolecular crosslinks. These features, alongside the reversible nature of halogen bonding, provide a robust modular approach for nanofabrication.
