Alignment of Lamellar Block Copolymer Microstructure in an Electric Field. 2. Mechanisms of Alignment

Amundson, Karl; Helfand, Eugene; Quan, Xina; Hudson, Steven D.; Smith, Steven D.

doi:10.1021/ma00100a047

Cited by 251 publications

(334 citation statements)

References 5 publications

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“…As described in [4] and [5] for this calculation a mean statistical segment length b = 7.1Å was assumed, while the approximation b = ρ −1/3 m used here implies b ≈ 5.2Å [27]. This comparison reflects the limits of the above approximation.…”

Section: Resultsmentioning

confidence: 83%

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Fluctuation Effects in the Theory of Microphase Separation of Diblock Copolymers in the Presence of an Electric Field

et al. 2007

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We generalize the Fredrickson-Helfand theory of the microphase separation in symmetric diblock copolymer melts by taking into account the influence of a time-independent homogeneous electric field on the composition fluctuations within the self-consistent Hartree approximation. We predict that electric fields suppress composition fluctuations, and consequently weaken the first-order transition. In the presence of an electric field the critical temperature of the order-disorder transition is shifted towards its mean-field value. The collective structure factor in the disordered phase becomes anisotropic in the presence of the electric field. Fluctuational modulations of the order parameter along the field direction are strongest suppressed. The latter is in accordance with the parallel orientation of the lamellae in the ordered state.

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Section: Resultsmentioning

confidence: 83%

“…(34-35) are our main results. The terms in (34-35) depending on α describe the effects of the electric field on fluctuations, and were not considered in previous studies [3]- [4]. This influence of the electric field on fluctuations originates from the termγ el 2 (q) under the integral in Eq.…”

Section: Resultsmentioning

confidence: 99%

Fluctuation Effects in the Theory of Microphase Separation of Diblock Copolymers in the Presence of an Electric Field

et al. 2007

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“…Instead, electric field is sufficiently high to orient the composition fluctuations in the non-phase separated region, leading to the appearance of perpendicular lamellae at the middle of the film. Subsequently, the parallel layers near the walls also collapse and the rearrangement of perpendicular lamellae proceeds by defect annihilation mechanism [46]. The average density profile in Fig.…”

Section: Thicker Films With Ly >> Lomentioning

confidence: 97%

Influence of substrate interaction and confinement on electric-field-induced transition in symmetric block-copolymer thin films

Mukherjee

Ankit

et al. 2016

Phys. Rev. E

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In the present work, we study morphologies arising due to competing substrate interaction, electric field and confinement effects on a symmetric diblock copolymer. We employ a coarse grained non-local Cahn-Hilliard phenomenological model taking into account the appropriate contributions of substrate interaction and electrostatic field. The proposed model couples the Ohta-Kawasaki functional with Maxwell equation of electrostatics, thus alleviating the need for any approximate solution used in previous studies. We calculate the phase diagram in electric field-substrate strength space for different film thicknesses. In addition to identifying the presence of parallel, perpendicular and mixed lamellae phases similar to analytical calculations, we also find a region in the phase diagram where hybrid morphologies (combination of two phases) coexist. These hybrid morphologies arise either solely due to substrate affinity and confinement or are induced due to the applied electric field. The dependence of the critical fields for transition between the various phases on substrate strength, film thickness and dielectric contrast is discussed. Some preliminary 3D results are also presented to corroborate the presence of hybrid morphologies.

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“…It has also been reported that the orientation of a mesophase such a lamellar or cylinder structure of block copolymer melt can be controlled by applying electric field. [5][6][7][8][9][10][11] For instance, an orientation of cylinder structure can be aligned along the direction of applied electric field. As other applications, there are fabrications 12,13) of nano-scale fiber using electric field, what we call, electro-spinning of polymer solutions 14) and melts.…”

Section: Introductionmentioning

confidence: 99%

Electric Field Induced Surface Profile Change of Liquid Film on a Periodically Aligned Electrode Array

Mizuochi

Taniguchi

Sugimoto

et al. 2010

J. Soc. Rheol., Jpn

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We investigated changes in surface profile of a dielectric liquid film put on a periodically aligned electrode array by imposing a voltage between adjacent electrodes. It is found that the surface of liquid film can be undulated by the electric field according to the periodicity of electrode array, and it rises on between adjacent positive and negative electrodes, on the other hand, it goes down at the central region on each electrode. The averaged height difference of undulated surface is proportional to the square of the interface electric field. It is also found that the averaged height difference increases with the width L of electrode for L < 1600 mm, decreases with L for L > 1600 mm, if the distance between adjacent electrodes is maintained constant. The averaged height difference does not change if the strength of interface electric field is adjusted to be the same for various thicknesses of liquid films. The time evolution of the height difference is also investigated using samples with various kinetic viscosities. It is found that the needed time t 1/2 for the surface height difference to reach the half of the equilibrium one is proportional to the kinetic viscosity of the sample.

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Alignment of Lamellar Block Copolymer Microstructure in an Electric Field. 2. Mechanisms of Alignment

Cited by 251 publications

References 5 publications

Fluctuation Effects in the Theory of Microphase Separation of Diblock Copolymers in the Presence of an Electric Field

Fluctuation Effects in the Theory of Microphase Separation of Diblock Copolymers in the Presence of an Electric Field

Influence of substrate interaction and confinement on electric-field-induced transition in symmetric block-copolymer thin films

Electric Field Induced Surface Profile Change of Liquid Film on a Periodically Aligned Electrode Array

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