Self-assembled patterns of block copolymer/homopolymer blends.

摘要

Many researchers have studied the orientation behavior of block copolymers (BCPs) with the most recent works directed towards nanotechnologies. Self-assembly of block copolymers is very relevant in controlling periodic nanostructures for nanotechnological applications. Nanotechnological applications of BCPs are possible due to their physical properties related to mass and energy transport, as well as mechanical, electrical, and optical properties. These properties provide substantial benefits in nanostructure membranes, nanotemplates, photonic crystals, and high-density information storage media. In many applications, such nanopatterns need to be achieved as ordered and tunable structures. Consequently, the control of orientation of such structures with defect-free ordering on larger length scales still remain as 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 nanostructural self-assembly.;We prepared well-aligned nanocylinders into block copolymer over the enhanced sample area and scale of height without any external field applications or modification of interaction between the sample and the substrate. Self-assembled 3-dimensional perpendicular cylinder orientation was achieved mainly by blending of minority homopolymer into the blockcopolymer. Thus, this study investigated a spontaneous and simple method for the orientation of perpendicular cylinders in BCP/homopolymer mixtures on a preferential substrate, by increasing the interaction force between the homologous polymer pair at a fixed composition of minority block component. Since the thermodynamical changes have been simply accomplished by the control of incompatibility between the block components, the intrinsic advantages of block copolymer nanopatterning, such as fast and spontaneous 3-dimensional nanopatterning with a high thermodynamic stability and reproducibility, have been completely preserved in this fabrication strategy. By exploiting thermodynamical changes using temperature variation and by blending a homopolymer with well controlled molecular weight, we illustrated that redistribution of homopolymer resulted in a shift of phase boundaries and in the stabilization of well-ordered structures to create new opportunities for nanotechnologies.