Electric Field Alignment of a Block Copolymer Nanopattern: Direct Observation of the Microscopic Mechanism

Olszowka, Violetta; Hund, Markus; Kuntermann, Volker; Scherdel, Sabine; Tsarkova, Larisa; Böker, Alexander

doi:10.1021/nn900081u

Cited by 115 publications

(112 citation statements)

References 46 publications

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“…21 Analysis of the phase behavior under controlled solvent vapor treatment allowed to gain important insights into the mechanisms of microphase separation of conjugated polymers, 5 and of microdomain reorientation and ordering under combined application of solvent annealing and of electric field. [55][56][57][58] Furthermore, confinement effects on the microphase separation and swelling of thin 24,59 and thick 55,37 block copolymer films have become evident in the thickness-dependent swelling as well as in heterogeneous swelling of block copolymer films. 24,60,61 In the last years similar climate-controlled solvent-vapor annealing devices have been adopted and successfully exploited by several research groups.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports

2014

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We studied solvent-driven ordering dynamics of block copolymer films supported by a densely cross-linked polymer network designed as organic hard mask (HM) for lithographic fabrications.The ordering of microphase separated domains at low degrees of swelling corresponding to intermediate/strong segregation regimes was found to proceed significantly faster in films on a HM layer as compared to similar block copolymer films on silicon wafers. The ten-fold enhancement of the chain mobility was evident in the dynamics of morphological phase transitions and of related process of terrace-formation on a macroscale, as well as in the degree of long-range lateral order of nanostructures. The effect is independent of the chemical structure and on the volume composition (cylinder-/ lamella-forming) of the block copolymers. In-situ ellipsometric measurements of the swelling behavior revealed a cumulative increase in 1-3 vol.2 % in solvent up-take by HM-block copolymer bilayer films, so that we suggest other than dilution effect reasons for the observed significant enhancement of the chain mobility in concentrated block copolymer solutions. Another beneficial effect of the HM-support is the suppression of the film dewetting which holds true even for low molecular weight homopolymer polystyrene films at high degrees of swelling. Apart from immediate technological impact in block copolymer-assisted nanolithography, our findings convey novel insight into effects of molecular architecture on polymer-solvent interactions.

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Section: Introductionmentioning

confidence: 99%

Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports

2014

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“…[ 96 ] , that employed an alignment index similar to the three-dimensional orientational order parameter for liquid crystals (see e.g. p. 260 in Ref.…”

Section: Application To Experimental Image Datamentioning

confidence: 99%

Minkowski Tensor Shape Analysis of Cellular, Granular and Porous Structures

et al. 2011

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Predicting physical properties of materials with spatially complex structures is one of the most challenging problems in material science. One key to a better understanding of such materials is the geometric characterization of their spatial structure. Minkowski tensors are tensorial shape indices that allow quantitative characterization of the anisotropy of complex materials and are particularly well suited for developing structure-property relationships for tensor-valued or orientation-dependent physical properties. They are fundamental shape indices, in some sense being the simplest generalization of the concepts of volume, surface and integral curvatures to tensor-valued quantities. Minkowski tensors are based on a solid mathematical foundation provided by integral and stochastic geometry, and are endowed with strong robustness and completeness theorems. The versatile definition of Minkowski tensors applies widely to different types of morphologies, including ordered and disordered structures. Fast linear-time algorithms are available for their computation. This article provides a practical overview of the different uses of Minkowski tensors to extract quantitative physically-relevant spatial structure information from experimental and simulated data, both in 2D and 3D. Applications are presented that quantify (a) alignment of co-polymer films by an electric field imaged by surface force microscopy; (b) local cell anisotropy of spherical bead pack models for granular matter and of closed-cell liquid foam models; (c) surface orientation in open-cell solid foams studied by X-ray tomography; and (d) defect densities and locations in molecular dynamics simulations of crystalline copper.

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“…Accordingly, different approaches for controlling the orientation of microphase-separated nanostructures from self-assembled BCP have been developed. These approaches include solvent evaporation, 7-10 solvent annealing, [11][12][13][14][15] the application of shear fields, [16][17][18][19][20] the application of electric fields, [21][22][23] the use of temperature gradients, 24,25 epitaxial crystallization, [26][27][28] chemical patterning of the surface [29][30][31][32][33] and graphoepitaxy. [34][35][36][37][38] Solvent field (that is, solvent evaporation or solvent annealing) has proven to be a very simple, yet highly effective, method to manipulate the orientation and lateral ordering of BCP microdomains.…”

Section: Orientation Of Bcp Thin Filmsmentioning

confidence: 99%

Nanostructured thin films of degradable block copolymers and their applications

She

Hsueh

et al. 2013

NPG Asia Mater

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Nanopatterning using self-assembled thin films of degradable block copolymers (BCPs) has attracted considerable attention and inspired a variety of appealing applications in different research areas. To create useful nanopatterns for practical uses, controlling the orientation of the BCP microdomains is essential. The generation of oriented microdomains in BCP thin films will be discussed in this article. This discussion is followed by a review of methods that use polylactide-containing BCP (that is, polystyrene-b-poly(L-lactide) (PS-PLLA)) thin films to generate nanoporous PS after hydrolysis, which can be used for templated synthesis to create functional nanohybrids. The nanoporous PS thin films with well-oriented cylinder nanochannels can be used for pore-filling various ingredients to create specific drug delivery systems and optoelectronic devices. Moreover, by utilizing templated synthesis, nanoporous ceramics with a high-specific surface area and high porosity can be fabricated for optical applications using hydrolyzed gyroid-forming PS-PLLA as a template for the sol-gel reaction. In addition, the nanolithography applications using silicon-containing BCP (that is, polystyrene-b-polydimethylsiloxane) thin films, which can form inorganic nanoporous templates after oxygen plasma treatment, will be discussed in this review. In recent decades, block copolymers (BCPs) have been extensively investigated because of their ability to self-assemble into various ordered nanostructures, such as spheres, cylinders, gyroids and lamellae, owing to the incompatibility of their constituent blocks and the corresponding chemical junction. 1,2 Well-defined nanostructured phases can be tailored by the molecular engineering of synthetic BCPs to obtain promising features for nanotechnological applications. For such nanostructured materials to prove useful in thin-film applications, thin-film samples with oriented periodic arrays over a large area must be formed to generate a uniform thickness and sufficiently thin films with well-ordered BCP microdomains. Nanoporous materials from BCP thin films have been attracted considerable attention owing to their appealing applications in different research areas. The etching techniques used to generate nanoporous materials can be classified as wet and dry processes depending on the etching methods. 3 The wet etching process is a common approach for fabricating nanoporous materials. By utilizing the degradable character of polymer chains, nanoporous polymers can be fabricated using self-assembled nanostructures through the selective degeneration of one of the constituent blocks. For instance, polylactide-containing BCPs can be used to fabricate nanoporous polymeric materials because of the unstable character of the ester group, which can be hydrolytically decomposed. 4 After hydrolysis of the polylactide segments, a nanoporous thin film with a uniform thickness and domain size can be successfully prepared on different substrates. Consequently, the nanoporous thin films can be used as nanor...

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Electric Field Alignment of a Block Copolymer Nanopattern: Direct Observation of the Microscopic Mechanism

Cited by 115 publications

References 46 publications

Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports

Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports

Minkowski Tensor Shape Analysis of Cellular, Granular and Porous Structures

Nanostructured thin films of degradable block copolymers and their applications

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