Directed Self‐Assembly of Star‐Block Copolymers by Topographic Nanopatterns through Nucleation and Growth Mechanism

Abstract

Exploring the ordering mechanism and dynamics of self-assembled block copolymer (BCP) thin films under confined conditions are highly essential in the application of BCP lithography. In this study, it is aimed to examine the self-assembling mechanism and kinetics of silicon-containing 3-arm star-block copolymer composed of polystyrene (PS) and poly(dimethylsiloxane) blocks as nanostructured thin films with perpendicular cylinders and controlled lateral ordering by directed self-assembly using topographically patterned substrates. The ordering process of the star-block copolymer within fabricated topographic patterns with PS-functionalized sidewall can be carried out through the type of secondary (i.e., heterogeneous) nucleation for microphase separation initiated from the edge and/or corner of the topographic patterns, and directed to grow as well-ordered hexagonally packed perpendicular cylinders. The growth rate for the confined microphase separation is highly dependent upon the dimension and also the geometric texture of the preformed pattern. Fast self-assembly for ordering of BCP thin film can be achieved by lowering the confinement dimension and also increasing the concern number of the preformed pattern, providing a new strategy for the design of BCP lithography from the integration of top-down and bottom-up approaches.

Insight into thermo-mechanical enhancement of polymer nanocomposites coated microsand proppants for hydraulic fracturing

“…FE-SEM (FEI Inspect S50) was used to monitor the morphologies of the proppant samples. The sample preparation for the SEM observations can be found elsewhere [ 45 , 46 , 47 , 48 , 49 , 50 ]. To record the images, an accelerating voltage of 2 kV was applied.…”

Rectangular Cylinders Formed by Compositionally Bidisperse ABC Triblock Terpolymer Blends: A Self-Consistent Field Theory Study

“…It should be noted that 2D simulations undoubtedly will miss some structures that can only be obtained in a 3D space, such as a spherical structure and bicontinuous gyroid structure. However, for some 3D structures that have translational invariance along a certain direction, such as lamella, and the cylindrical structures studied in this work, 2D simulation is appropriate and time efficient. − Moreover, a 2D system is generally in a close relationship to thin films; many potential applications, such as nanolithography and nanotemplate, highly depend on 2D ordered structures in thin films. − Therefore, 2D simulations are important for structure control in experiments.…”

“…Block copolymers (BCPs) have fascinating abilities to self-assemble into a rich variety of ordered nanoscale phases, − among which cylinder is the most common one. Cylinder-forming BCPs can form 2D long-range ordered cylindrical phases in thin films with controlled orientations, making the cylinder-forming BCPs ideal candidates for nanolithography and nanotemplate. − Various organic/inorganic nanostructures, including nanowire/-bar/-rod arrays − and nano-dot/-pore arrays, − have been successfully fabricated.…”

Directed Self-Assembly of Block Copolymers Based on the Heterogeneous Nucleation Process

“…Because the corner angle is 120°, which is commensurate in hexagonal pattern, this method is high-efficient. Because this method is ready to implement, Ho et al [41] realized a defect-free hexagonal pattern by self-assembly of star-block PS-PDMS based on heterogeneous nucleation. Although the hexagonal confinement is not difficult to produce technically, there is a better choice, such as rectangular confinement.…”