Effects of substrate-blocks interactions on the phase behaviors of cylinder-forming block copolymers

Abstract

Self-assembly of block copolymers greatly facilitates production of controlled periodic nanostructures for nanotechnological applications. Orientation control in such structures with defect-free ordering on larger length scales still remain a major research challenge in many cases. In addition to their pure block forms, blends of copolymers with other polymers offer productive research areas in relation to nanostructure self-assembly. We prepared well-aligned nanocylinders in block copolymers over an enhanced sample area and height scale without using any external field applications. Self-assembled 3-dimensional perpendicular cylinder orientation was achieved mainly by blending of minority homopolymer into the block copolymer. In this work, we illustrate that the mixed cylinder nanodomain orientation exits in block copolymer mixtures even with a relatively strong homologous polymer pair interaction and a decreased domain-domain excess free energy, when the interfacial interaction between the majority component and the substrate is high enough to restrict the perpendicular nanodomain orientation. In case of overall perpendicular cylinder-forming block copolymer mixtures, on the other hand, the strong homologous PS pair interaction overcomes the limitation from the relatively high domain-substrate interfacial interactions.

A General Method for Growing Large Area Mesoporous Silica Thin Films on Flat Substrates with Perpendicular Nanochannels

“…Recognizing this, Mou and co-workers were able to make free-standing platelets of SBA-15 with vertical channels by confining P123 and silica precursor between symmetric bilayers of a mixed cationic/anionic surfactant system of CTAB and SDS . For films on substrates, the problem of dissimilar interfaces has been found in thin films of cylinder-forming block copolymers . Recognizing this, Freer et al tuned the interfacial energy at both the air/film and film/substrate interfaces carefully to allow for control of cylindrical pore orientation normal to the supported film surfaces .…”

Structural Parameters for Nanocylinder Microdomains of Polystyrene-polybutadiene- Polystyrene Triblock Copolymer and its Blends with Polystyrene Homopolymer

“…To align block copolymer morphologies, perpendicular to the surface, the substrate can be coated with a thin layer of anchored random copolymers to provide a neutral surface [3,4], equally attractive for both blocks, or the application of high electric fields [5] allows one to overcome the surface effect. With our previous works [6][7][8][9][10] we illustrated a spontaneous and simple method to achieve a regularly ordered structure normal to the preferential substrates over a long range, without any external field application or modification of interfacial energy between the sample and the substrate. With our previous works [6][7][8][9][10] we illustrated a spontaneous and simple method to achieve a regularly ordered structure normal to the preferential substrates over a long range, without any external field application or modification of interfacial energy between the sample and the substrate.…”

“…Unfortunately, even though these methods are highly advanced, the technologies used to achieve perpendicular orientation are complicated and timeintensive. Thus, the exceptional strong segregation force between the homologous pairs was the most important factor to orient the nanocylinder structure normal to the preferential substrate [10]. The thermodynamic conditions of a triblock copolymer could be controlled by the interaction force between a homologous polymers pair with the addition of an appropriate homopolymer into the block copolymer.…”