Perpendicular orientation of sub-10 nm channels in polystyrene-b-poly(4-hydroxyl styrene)/PEG oligomer blend thin films

Abstract

Vertically oriented cylinders via the directional coalescence of the spheres embedded in the blend thin films from polystyrene-b-poly(4-hydroxyl styrene) (PS-b-PHS) and PEG induced by solvent annealing were achieved. Removal of PEG water led to the formation of nanochannels throughout the films. The diameter of these channels could be as small as 9 nm which might enhance the applicability of the nano-porous films as size-selective membranes and controllable drug delivery systems for the objects less than 10 nm.

Block copolymer self-assembly for nanophotonics

“…34 The control over domain alignment in thin films has indeed been a subject of intense study. Meanwhile a number of effective and less complex methods have been developed, including the utilisation of solvent casting, 35 thermal and solvent annealing methods, 36,37 photo-induced alignment, 38 as well as chemical templating, [39][40][41][42] chemoepitaxy, 43,44 and graphoepitaxy. 45,46 With gyroid-forming block copolymers, surface reconstruction into the lamellar phase is common, and causes a significant barrier to electrochemical replication.…”

Analysis of Homopolymer Distribution in a Polymer Blend Thin Film by Anomalous Grazing Incidence Small-Angle X-ray Scattering at the Bromine K-Edge

“…The sphere-to-cylinder transition is key for the formation of perpendicularly oriented cylindrical domains in the thin film. , In this study, this process took place as follows: after spin-casting the PS–PHS/Br-PHS blend solution on a silicon wafer, the spherical micelles were trapped and embedded in the thin film in a disordered lattice due to the fast evaporation of solvents. These spheres did not spontaneously reach an equilibrium state because polymer chains were in the glassy state at room temperature (20–25 °C); thus, their micro-Brownian motion was restricted.…”

“…A BCP consists of two or more incompatible polymer chains that can form a variety of self-assembled patterns, and BCP thin films can produce well-ordered arrays of microdomains. The orientation of microphase-separated structures in BCP thin films has been examined using irradiation with linearly polarized light, , thermal annealing, solvent annealing, − and controlled interfacial interactions . In particular, using multicomponent thin films comprising polymer blends or nanocomposites − enabled gaining new insights into the structures and functions of BCP.…”

“…The orientation of microphase-separated structures in BCP thin films has been examined using irradiation with linearly polarized light, , thermal annealing, solvent annealing, − and controlled interfacial interactions . In particular, using multicomponent thin films comprising polymer blends or nanocomposites − enabled gaining new insights into the structures and functions of BCP. However, the complexity of these multicomponent structures renders extensive analysis using X-ray scattering difficult.…”

Recent developments in polymer applications of synchrotron small‐angle X‐ray scattering

“…GISAXS is a useful technique and it has been applied to many polymeric functional materials in the form of thin films . Especially for block copolymer thin films, it is a powerful method for analyzing nanostructure and its orientation . It should also be noted that time‐resolved GISAXS measurements have been conducted for analyzing nanostructure formation process during the spin‐cast process, during the slot‐die coating process and during the solvent vapor annealing process .…”