Electric‐Field‐Induced Pattern Morphologies in Thin Liquid Films

Voicu, Nicoleta E.; Harkema, Stephan; Steiner, Ullrich

doi:10.1002/adfm.200500470

Cited by 91 publications

(104 citation statements)

References 23 publications

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“…The formed gratings would merge at the influence of resultant force with a small value, see Fig. 7E and F [7,20,33]. The coalescence is not an expected phenomenon, destroying the regularity of formed structures.…”

Section: Patterned Template In Electrically Induced Patterning Processmentioning

confidence: 91%

“…5A-D. However, the phenomenon of producing periodic pillars is not the final result if the applied voltage is continued [5,7,17,32]. The polymer would continue to flow and some pillars would merge together, see Fig.…”

Section: Flat Template In Electrically Induced Patterning Processmentioning

confidence: 94%

“…The template can be either a flat one (i.e. non-patterned), generating an array of periodic pillars [1,4], or a periodically patterned one in an attempt to duplicate various microstructures on the polymer, such as gratings and grids [1,[5][6][7], which coincide with the template pattern, as desired.…”

Section: Introductionmentioning

confidence: 99%

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Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow

et al. 2011

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Electrically induced patterning process, as a novel micro- or nano-structuring approach for fabrication of various micro- or nano-systems, is usually implemented by applying a voltage to an electrode pair consisting of a patterned or non-patterned template and a polymer-coated substrate separated in parallel by an air gap, followed by photo- or thermo-curing of the fluidic and dielectric polymer. The analyses performed so far to characterize this patterning process have been based on linear thermodynamics for a thermally instable thin film perturbed by an electrostatically induced hydraulic pressure. For mathematical simplicity, these analyses were formulated only for a flat template and a flat film surface with infinite planar area, demonstrating the tendency of initial pattern growth on the polymer film, but being unable to visualize the dynamic evolution of micro- or nano-structure growth throughout the patterning process for a real-life template in practical applications. This paper attempts to provide another insight into this patterning process from a viewpoint of liquid dielectrophoresis (L-DEP), by presenting an approach for numerical simulation of the patterning process based on a coupling of L-DEP and two-phase flow theories. First, a numerical analysis has been made for the electrocoalescence of a water droplet with bottom water in silicone oil to benchmark effectiveness of the proposed numerical approach against published experimental observations. More numerical results have then been provided to show effects of some process variables on the evolution of the polymer micro- or nano-structures for this patterning process.

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Section: Patterned Template In Electrically Induced Patterning Processmentioning

confidence: 91%

Section: Flat Template In Electrically Induced Patterning Processmentioning

confidence: 94%

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Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow

et al. 2011

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“…Confinement of a soft liquid [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] or a soft solid surface by external fields and residual stresses [11,12,33,34] often engenders the surface instability and self-organized patterning of the film surface. Such instabilities can also be often controlled and guided, [3][4][5][6]9,10,[12][13][14][15][16][17]28,[36][37][38][39] which may allow their potential technological use in the applications involving meso-scale patterning of soft materials.…”

Section: Introductionmentioning

confidence: 99%

Contact Instability of Elastic Bilayers: Miniaturization of Instability Patterns

Mukherjee

Pangule

Sharma

et al. 2007

Adv Funct Materials

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We show, both experimentally and theoretically, that the free surface of an elastic bilayer becomes spontaneously rough when brought in contact with another rigid surface. The lateral length scales of these self‐organized structures were found to scale as: λ = RF h, where h is the total bilayer thickness. The scale factor, RF could be modulated by the ratios of the individual film thicknesses and shear moduli. This is unlike the case of a single elastic film where the scale factor is independent of all material properties, RF ∼ 3. A linear stability analysis shows that the instability patterns in the bilayer can be tuned from the short waves (∼ 0.5 h) to long waves (∼ 8 h). Experiments show good agreement with the theoretical predictions regarding the existence of short wave deformations. Further, a rather catastrophic change in the wavelength from its minimum value, ∼h/2, to a limiting value of ∼ 3 h occurs by very small changes in the film thicknesses. This effect is explained by a switching of states in the bilayer energy curve which displays two minima at different wave numbers. Thus, the contact instability of elastic bilayers suggests novel strategies for the control of adhesion and engineering of feature sizes in a wide range. In particular, these findings have implications for further pattern miniaturization in the elastic contact lithography using pre‐patterned stamps.

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“…[31,32] By using heterogeneous fields (generated, e.g., by micro-patterned electrodes) nearly any pattern can be replicated into a homopolymer film. [33] Russell and coworkers used electrostatic forces to pattern block copolymer films with a cylindrical microphase morphology to create well-ordered patterns of columns, tens of micrometers in size. [34] Here we discuss the interplay of EHD structure formation with the structural control over a block copolymer microphase morphology.…”

mentioning

confidence: 99%

Alignment of Lamellar Block Copolymers via Electrohydrodynamic‐Driven Micropatterning

2008

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The combination of top-down approaches with block copolymer bottom-up self-assembly in a single processing step [1][2][3] has received increasing attention because of its potential use for sub-100-nm lithography. The so far unachieved principle employs block copolymer self-assembly for the controlled formation of 10-nm-sized patterns, which are interfaced by larger structures providing the addressability of self-assembled nanodevices. The successful implementation of such a device requires a simultaneous control over the self-assembly process and the large-scale structures. Both have been demonstrated individually in a number of ways, but their combination remains elusive. Block copolymers are ideal building blocks for 10-nm-sized structures because of their special molecular architecture. These macromolecules typically consist of two or more chemically dissimilar polymers which are covalently joined. The competition between the inherent incompatibility of the constituent polymers and their chemical linkage leads to a self-assembling process with structure sizes in the range of 5 to 50 nm.[4] The alignment of microdomains perpendicular to the substrate is important because this is a typical requirement for nanotechnological applications [5] and can be achieved by the confinement of thin block copolymer films or the application of external fields, such as mechanical shear fields and electric fields. The resulting nanostructures which are accessible from the air surface can for example be partially degraded thereby serving as templates for metals [6] and semiconducting [7] nanowires.The long-range lateral control over the orientation of block copolymer domains in polymer melts and solutions has been demonstrated in a number of ways, such as the use of steady shear, [8][9][10] capillary extrusion, [11] and elongational flow. [12,13] The roll-casting of solutions [14][15][16][17] or shearing of block copolymer films with silicon rubber pads [18] also results in a long-range order of microphase-separated block copolymer morphologies. The alignment of block copolymer morphologies using electric fields [19,20] is particularly interesting because of the level of control that can be achieved by this method. Since the domains follow the electric field lines, [21][22][23] the local alignment of the microphase morphology both perpendicular [24,25] and parallel [26][27][28][29][30] to the film-normal is possible. The long-range nature of electric fields results in an equally long-range alignment of the microphase morphology. Additionally large-scale topographic structures can be generated in a controlled fashion by a electrohydrodynamic (EHD) film instability.

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Electric‐Field‐Induced Pattern Morphologies in Thin Liquid Films

Cited by 91 publications

References 23 publications

Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow

Numerical studies of electrically induced pattern formation by coupling liquid dielectrophoresis and two‐phase flow

Contact Instability of Elastic Bilayers: Miniaturization of Instability Patterns

Alignment of Lamellar Block Copolymers via Electrohydrodynamic‐Driven Micropatterning

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