Long-Range Ordered Thin Films of Block Copolymers Prepared by Zone-Casting and Their Thermal Conversion into Ordered Nanostructured Carbon

Tang, Chuanbing; Tracz, A.; Kruk, Michał; Zhang, Rui; Smilgies, Detlef‐M.; Matyjaszewski, Krzysztof; Kowalewski, Tomasz

doi:10.1021/ja0508929

Cited by 216 publications

(226 citation statements)

References 15 publications

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“…Techniques for aligning block copolymer include solvent evaporation fields [46], physical epitaxy/graphoepitaxy [90], chemical epitaxy [4], optical (holographic) radiation [91], droplet pinning [92], shear forces [93], nanoimprint lithography [94], e-beam lithography [95], zone annealing [96] and casting [97]. We concentrate in this section on graphoepitaxy (including nanoimprint lithography) and chemical pre-patterning as these techniques represent the most practical methods for device integration.…”

Section: Block Copolymer Thin Filmsmentioning

confidence: 99%

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Farrell

Petkov²,

Morris

et al. 2010

Journal of Colloid and Interface Science

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Self-assembled nanoscale porous architectures, such as mesoporous silica films (MPS), block copolymer films (BCP) and porous anodic aluminas (PAAs), are ideal hosts for templating one dimension (1 D) nano-entities for a wide range of electronic, photonic, magnetic and environmental applications. All three templates offer dimensional scalability and tunability over a wide range, with critical pore sizes for each system well below the 20 nm threshold [1][2][3]. Recently, research has progressed towards controlling the pore direction, orientation and long range order of these nanostructures through so called directed self-assembly (DSA). Significantly, the introduction of a wide range of top-down chemically and physically pre-patterning substrates has facilitated the DSA of nanostructures into functional device arrays. The following review begins with an overview of the fundamental aspects of self-assembly and ordering processes during the formation of PAAs, BCPs and MPS films. Special attention is given to the different ways of directing self-assembly, concentrating on properties such as uni-directional alignment, precision placement and registry of the self-assembled structures to hierarchal or top down architectures. Finally, to distinguish this review from other articles we focus on research where nanostructures have been utilised in part to fabricate arrays of functioning devices below the sub 50 nm threshold, by subtractive transfer and additive methods. Where possible, we attempt to compare and contrast the different templating approaches and highlight the strengths and/or limitations that will be important for their potential integration into downstream processes. ACCEPTED MANUSCRIPT 3 SECTION 1.0: SELF ASSEMBLY AND NANO-ARCHITETCURESThe diversity of self-assembled nanostructures and more importantly, their precise orientation within a thin film (fixed to a substrate) ultimately determines their function and overall application. A large population of research reports to date have focused on identifying these orientations and related periodicities, using x-ray and microscopy tools, as well the development of methods for readily manipulating nanostructures, such as pre-patterning of silicon substrates for the alignment of block copolymers (BCPs) [4] and mesoporous thin films (MTFs) [5] and altering the growth direction of porous anodic alumina (PAA) templates [6]. In this section, a brief synopsis of the mechanisms behind the self-assembly/organisation of each system and highlight nanoscale architectures (and orientations), which are important from a device perspective. Templated mesoporous thin filmsOrdered mesoporous powders were first discovered by researchers at the Mobil Petrochemical Corporation in 1992 and shortly after, sol-gel derived mesoporous silica films were fabricated [1,7].The first series of ordered mesoporous films were reported by Yang et al. in 1996 [8], prepared using initial surfactant concentrations above their critical micelle concentration (CMC). However the films prepared fil...

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Section: Block Copolymer Thin Filmsmentioning

confidence: 99%

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Farrell

Petkov²,

Morris

et al. 2010

Journal of Colloid and Interface Science

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“…In the second category, uniform solvent annealing [19] can increase BCP grain size to a few microns without imposing a preferential direction to the pattern; by creating a moving gradient in solvent concentration, "zone-casting" from solution can produce macroscopically-aligned specimens. [20] Similarly, uniform thermal annealing [21,22] increases the grain size without imposing a preferential direction, but the grain size grows only as the 1 ⁄4 power of annealing time; the effect of a moving temperature gradient on a block copolymer thin film has not been reported previously.Hashimoto et al [23] showed that sweeping a strong temperature gradient through a bulk specimen of a lamellar BCP, such that the material is heated above its order-disorder transition temperature, can produce strong alignment; as the material cools in the gradient, ordered lamellae grow from the disordered phase, with the lamellar planes aligned normal to the direction of the moving gradient. Though directional solidification has not been reported for neat BCP thin films, directional crystallization of a small-molecule solvent from a BCP solution has been reported by Thomas and co-workers; [24,25] crystallization of the solvent concentrates the BCP and drives it to order, similar to what zone-casting [20] achieves through solvent evaporation.…”

mentioning

confidence: 98%

“…[20] Similarly, uniform thermal annealing [21,22] increases the grain size without imposing a preferential direction, but the grain size grows only as the 1 ⁄4 power of annealing time; the effect of a moving temperature gradient on a block copolymer thin film has not been reported previously.…”

mentioning

confidence: 98%

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

et al. 2007

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The use of block copolymer (BCP) thin films as self-assembled templates has become increasingly popular as an economical nanofabrication technique, with new applications and techniques constantly being developed. This bottom-up approach to nanofabrication is extremely versatile; BCP films have been used as sacrificial contact masks for thin-film lithography to produce nanometer-scale periodic patterns in a wide variety of materials, [1][2][3] which have been investigated in the data storage sector for high-density magnetic [4,5] and nano-crystal FLASH memories. [6,7] While the nanoscale domains (spheres, cylinders, etc.) typically organize into grains of micron or smaller size, with no overall orientation, several methods have been developed to direct the domain orientation, or simply increase the grain size, in BCP films. In the first category, epitaxy [8,9] can direct the alignment over large areas, but requires substrates pre-patterned at the nanometer scale; graphoepitaxy [10][11][12] creates needle-like grains very long in one dimension, but at most a few microns wide; electric fields [13] generate alignment parallel to the field direction over squaremicron areas; polarized light can create arbitrary orientation patterns in liquid-crystalline block copolymers with photoalignable side groups; [14,15] and shear can align BCP cylinders [16] and spheres [17,18] over square-centimeter areas, with an orientation specified by the shear direction. In the second category, uniform solvent annealing [19] can increase BCP grain size to a few microns without imposing a preferential direction to the pattern; by creating a moving gradient in solvent concentration, "zone-casting" from solution can produce macroscopically-aligned specimens. [20] Similarly, uniform thermal annealing [21,22] increases the grain size without imposing a preferential direction, but the grain size grows only as the 1 ⁄4 power of annealing time; the effect of a moving temperature gradient on a block copolymer thin film has not been reported previously.Hashimoto et al. [23] showed that sweeping a strong temperature gradient through a bulk specimen of a lamellar BCP, such that the material is heated above its order-disorder transition temperature, can produce strong alignment; as the material cools in the gradient, ordered lamellae grow from the disordered phase, with the lamellar planes aligned normal to the direction of the moving gradient. Though directional solidification has not been reported for neat BCP thin films, directional crystallization of a small-molecule solvent from a BCP solution has been reported by Thomas and co-workers; [24,25] crystallization of the solvent concentrates the BCP and drives it to order, similar to what zone-casting [20] achieves through solvent evaporation. When the solvent is directionally crystallized on a cold substrate, an aligned BCP film is left on the surface of the frozen solvent, but with a defect density higher than obtained with the methods discussed in the preceding paragraph. Our present study demonstr...

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“…[9][10][11] Especially, the controlled structuring of large surface areas of many square millimeters remains challenging. Preparation routes based on diblock copolymers require the use of external fields and several special chemical steps to end up with highly aligned polymer nanochannels: [12][13][14][15] With the help of the external field, the local lamellar order is expanded in a stripe-like pattern and a secondary chemical treatment is necessary to remove one block, yielding the nanochannels. Preparation routes based on optical interference result in large scale and extremely perfect surface gratings, 16 but the special type of equipment required does not match the idea of a simple process.…”

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confidence: 99%

Route to create large-area ordered polymeric nanochannel arrays

Müller‐Buschbaum

Bauer

Maurer

et al. 2006

Applied Physics Letters

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Depositing polymdimethylsiloxane ͑PDMS͒ from an isopropanol solution onto a glass slide surface by wiping with a fuzz-free wipe results in highly ordered structures. Dewetting of the highly diluted PDMS solution and evaporation of the solvent yields nanostructures. The structure is well characterized as polymer nanochannels, separated by a mean distance of 166 nm. The mean height of the shallow channels is 3 nm only. The proof of having aligned structures on very large surface areas with a well defined orientation is performed with a very high resolution grazing incidence small angle x-ray scattering setup.

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Long-Range Ordered Thin Films of Block Copolymers Prepared by Zone-Casting and Their Thermal Conversion into Ordered Nanostructured Carbon

Cited by 216 publications

References 15 publications

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

Route to create large-area ordered polymeric nanochannel arrays

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