Nanostructured Morphologies by Self-Assembly of Diblock Copolymers: A Review

Abstract

Due to the thermodynamic incompatibility between blocks, diblock copolymers can selfassemble in a wide variety of nanostructures, covalent linkage among blocks preventing the phase separation at macroscopic scale. Those nanostructures depend on copolymer composition (f), Flory-Huggins interaction parameter among both blocks (χ), and polymerization degree of the copolymer (N). Thin films of block copolymers can show different equilibrium morphologies such as spheres, cylinders, gyroids, and lamellas. Besides mentioned parameters, film preparation process (substrate, annealing process if any) and used solvent will determine self-assembled morphology. In the present review, the most important morphologies or microstructures obtained for different diblock copolymer films are presented, as well as the most important phase transitions among them. Different microstructures and the way in which they can be obtained become of great importance, as they could be used as templates for nanoparticle deposition, nanolithography, or nanopatterned materials with several potential applications in different fields such as nanoelectronics or nanomedicine.

Fine‐tuning in‐plane interdomain spacing of polystyrene‐b‐poly(ethene‐co‐butadiene)‐b‐polystyrene triblock copolymer adding monodisperse polystyrene

“…Other studies have already shown this difficulty using a substrate other than mica 24,25 and report thermal and/or solvent vapor annealing as alternatives for enhancing self-organization. 24 The greater roughness and mainly the poor interactions between the polymer and upper bounding surface were determinants for the absence of spontaneous submicrometric patterned structures. 18,24,26 Regarding the interactions between these pairs, besides the annealing process, several other techniques are usually adopted to tune the wetting behavior of a surface, for instance chemically patterned surfaces 26 just by controlling interfacial energies of polymers in contact with the substrates and allowing greater affinities between them.…”

“…Other studies have already shown this difficulty using a substrate other than mica 24,25 and report thermal and/or solvent vapor annealing as alternatives for enhancing self-organization. 24 The greater roughness and mainly the poor interactions between the polymer and upper bounding surface were determinants for the absence of spontaneous submicrometric patterned structures.…”