Thin Films with Perpendicular Tetragonally Packed Rectangular Rods Obtained from Blends of Linear ABC Block Terpolymers

Abstract

A binary blend of poly(isoprene-block-styrene-block-(2-vinylpyridine)) (ISP) triblock terpolymers, having the same chain length but different compositions, was used to achieve an ordered lattice with 4-fold symmetry of rectangular-shaped rods of poly(isoprene) (I) and poly(2-vinylpyiridine) (P). In given conditions, the I and P domains were oriented perpendicularly to the substrate, providing new appealing type of templates for nanopatterning. Thin films were prepared by spin coating, exposed to solvent vapor (providing morphological reorganization) and then characterized by Atomic Force Microscopy, Transmission Electron Microscopy and Grazing-Incidence Small-Angle X-Ray scattering. Selective I and P identifications were carried out by AFM and TEM on a model ISP, as well as development of a technique of electronic contrast enhancement to better assign the self-assembly structure in GISAXS

Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials

“…The disadvantage of BCP self-assembly stands in the formation of defects [ 210 ]. Instead, directed self-assembly [ 211 ] uses various external stimuli (e.g., thermal annealing [ 197 , 199 , 209 , 212 , 213 , 214 ], solvent annealing [ 199 , 200 , 209 , 215 ], thermal and solvent annealing [ 199 ], ultrasounds [ 216 ], microwaves [ 217 ], magnetic fields [ 218 ], photoirradiation [ 219 ], shearing [ 220 ], addition of an ionic liquid [ 221 ], controlled spreading area [ 222 ], or epitaxy [ 210 , 223 ]) in order to induce and favor the self-assembly process. This process is also favored when employing click chemistry [ 214 ], and it displays a series of advantages: high-quality hierarchical [ 195 , 224 ] nanostructures exhibiting a low number of defects can be rapidly generated [ 195 , 213 ] over a large area [ 222 ].…”

“…In the past years, BCPL was widely used in nanotechnological applications [ 200 , 208 , 211 , 217 ], including opto- [ 207 ] and microelectronics [ 228 ]. This method has proven itself to be a highly promising method, especially because it relies on a multitude of ordered structures obtained by directed and self-assembly such as parallel or perpendicularly oriented lamellar structures [ 26 , 219 , 221 , 225 , 226 , 228 , 229 ], (hexagonally packed) cylinders [ 26 , 199 , 217 ], semispherical [ 197 ] or body-centered cubic spherical structures [ 26 ], nanomesh structures [ 209 ], strand structures [ 222 ], double-gyroids [ 26 ], square, rectangular, and rhombic arrays of BCPs [ 220 ], quasi-hexagonal micellar structures [ 216 ], Archimedean tilings [ 200 ], and more [ 195 , 212 , 213 , 215 , 218 , 232 ]. Moreover, other more complex 2D [ 195 ] and hierarchical [ 195 ] or non-native [ 232 ] 3D BCP structures can be obtained via multiple self-assembly (because the fabrication of ordered structures requires an extremely precise control over ordering in BCP thin films [ 229 ], the latter can be further improved [ 216 , 218 ] inclusively through the use of chemical vapor deposition [ 201 ]).…”

Nonclassical Block Copolymer Self‐Assembly Resulting from a Constrained Location of Chains and Junctions

“…It is worth noting that this tetragonal arrangement of rectangular‐shaped rods was recently reproduced in thin films by Guliyeva et al in a 2018 paper. [ 16 ] Making such an unusual morphology in thin film offers an exciting potential for nanopatterning where the need for rectangular‐shaped features in a square symmetry is high, since it is more compatible with the device layout design rules of the microelectronics industry. [ 17–19 ] In two following papers, [ 20,21 ] the same group explored the behavior of blends of ISP having a larger window composition and/or different molar mass.…”

Self‐Assembly of Multiblock Copolymers

“…Blending of triblock terpolymer morphologies with homopolymers or hydrogen bonded triblock terpolymers of different composition generated unprecedented rectangular cylinders in a tetragonal unit lattice, [58] tetragonally-packed spheres, core/shell double gyroids [59] or rectangular-shaped rods. [60] These blending examples teach that there are likely to be more BCP morphologies hidden in unexplored areas of the ternary microphase diagram as well as hierarchical structures by loading of individual microdomains with small molecular weight additives.…”