Novel 3-D Structures in Polymer Films by Coupling External and Internal Fields

Dickey, Michael D.; Gupta, Suresh; Leach, K. Amanda; Collister, Elizabeth; Willson, C. Grant; Russell, Thomas P.

doi:10.1021/la052954e

Cited by 51 publications

(51 citation statements)

References 13 publications

(18 reference statements)

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“…The polymeric permanent structures are generated in our case by rapid crosslinking, which allows us to reduce the overall process duration from hours, required for the glass transition, down to seconds. The combination of high viscosity (12) and rapid cross-linking of PDMS allows us to fabricate structures with aspect ratios extraordinary higher, up to three orders of magnitude, compared to those reported in previous articles (8)(9)(10)19). In fact, the typical aspect-ratio values reported in previous works are in the range of 0.29-0.83, whereas up to 186 is reached here.…”

Section: Design and Working Principle Of The Techniquementioning

confidence: 50%

3D lithography by rapid curing of the liquid instabilities at nanoscale

Grilli

Coppola

Vespini

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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In liquids realm, surface tension and capillarity are the key forces driving the formation of the shapes pervading the nature. The steady dew drops appearing on plant leaves and spider webs result from the minimization of the overall surface energy [Zheng Y, et al. (2010) Nature 463:640-643]. Thanks to the surface tension, the interfaces of such spontaneous structures exhibit extremely good spherical shape and consequently worthy optical quality. Also nanofluidic instabilities generate a variety of fascinating liquid silhouettes, but they are however intrinsically short-lived. Here we show that such unsteady liquid structures, shaped in polymeric liquids by an electrohydrodynamic pressure, can be rapidly cured by appropriate thermal treatments. The fabrication of many solid microstructures exploitable in photonics is demonstrated, thus leading to a new concept in 3D lithography. The applicability of specific structures as optical tweezers and as novel remotely excitable quantum dots-embedded microresonators is presented.A wide variety of lithographic techniques have been developed for fabricating 3D structures (1-5), such as soft lithography (6) that allows one to develop lab-on-chip devices with applications ranging from organic light emitting diode to biology and biochemistry (7). Among others, "capillary-force lithography" is able to nicely pattern polymers at nano-/microscale, but with a very low aspect ratio, in a single step and avoiding the use of external forces (8). Other approaches generate self-patterned structures by using destabilizing forces produced by electric fields, namely electrohydrodynamic (EHD) lithography (9). In EHD lithography, amazing polymeric patterns have been reported, demonstrating the possibility of controlling the process with high accuracy. This method appears suitable only for a few types of periodic patterns having a relatively low aspect ratio (i.e., pillars, dots, and lines). In fact, the control of liquid film instabilities is a demanding task as very little perturbations could drag the nanofluidic system toward nonfully predictable configurations. Such occurrence, for high aspect-ratio features, would prevent the achievement of the expected final steady state. The EHD lithography is usually performed at temperatures above the glass transition of the polymer film [typically polystyrene or poly (methyl methacrylate)], obtaining permanent microstructures by slow annealing and successive cooling, taking hours (10-13).In general, the hydrodynamic techniques produce steadystate structures resulting from the equilibrium state of a specific fluidic effect. Conversely, the core of our approach consists in "rapid-curing" temporary structures, which evolve continuously under specific fluidic instabilities, by a fast heating procedure. The interesting aspect of this approach is that it gives access to very intriguing fluid shapes, occurring in unsteady fluid physics at nanoscale, which could be very useful in modern science. As investigated recently, breakup of viscoelastic filaments...

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Section: Design and Working Principle Of The Techniquementioning

confidence: 50%

3D lithography by rapid curing of the liquid instabilities at nanoscale

Grilli

Coppola

Vespini

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Dewetting 1-50 and electric field induced instabilities of thin liquid layers [89][90][91][92][93] and bilayers [48][49][50][81][82][83][84][85][86][87][94][95][96] have emerged as promising techniques for mesoscale pattern formation. Large-area ordered polymer patterns find diverse applications in the fabrication of micro-and optoelectronic devices, biosensors, microfluidic devices and fuel and solar cell technologies.…”

Section: Introductionmentioning

confidence: 99%

Electric field induced microstructures in thin films on physicochemically heterogeneous and patterned substrates

Srivastava

Reddy

Wang

et al. 2010

The Journal of Chemical Physics

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We study by nonlinear simulations the electric field induced pattern formation in a thin viscous film resting on a topographically or chemically patterned substrate. The thin film microstructures can be aligned to the substrate patterns within a window of parameters where the spinodal length scale of the field induced instability is close to the substrate periodicity. We investigate systematically the change in the film morphology and order when (i) the substrate pattern periodicity is varied at a constant film thickness and (ii) the film thickness is varied at a constant substrate periodicity. Simulations show two distinct pathway of evolution when the substrate-topography changes from protrusions to cavities. The isolated substrate defects generate locally ordered ripplelike structures distinct from the structures on a periodically patterned substrate. In the latter case, film morphology is governed by a competition between the pattern periodicity and the length scale of instability. Relating the thin film morphologies to the underlying substrate pattern has implications for field induced patterning and robustness of inter-interface pattern transfer, e.g., coding-decoding of information printed on a substrate.

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“…As dewetting occurs with both materials containing azobenzene chromophores and mexylaminotriazine units, this behavior is likely due to the presence of aromatic moieties, as is the case with most reported instances of polymers that can undergo electric fieldinduced dewetting, including polystyrene and polyaniline. [22][23][24][25][26][27] It is also likely that similar behavior is shared with other classes of polar glass-forming organic compounds, but similar experiments have not been previously reported with other small-molecule materials. As previous studies 35 on mexylaminotriazine glasses had shown that dewetting could occur upon thermal annealing of the films over Tg in certain cases depending on the respective polarities of the material and the substrate, it is crucial to determine if the observed behavior is caused by the electric field, or if it is only due to heating.…”

Section: Resultsmentioning

confidence: 77%

“…In particular, applying electric fields to cause surface patterning is appealing because the size of the surface features can be controlled by the strength of the electric field. This phenomenon has been previously studied through simulations 20,21 , and it has been experimentally accomplished on viscous and elastic thin film bilayers 22 , PMMA-Polystyrene bilayers [23][24][25] and trilayers 26 , as well as on thin films of polyaniline conducting polymers 27 . While this behavior has been reported for single polymers, the large majority of reports on electric field-induced surface deformation are on polymer materials in multilayer configurations.…”

Section: Introductionmentioning

confidence: 99%

Electric-Field-Induced Nanoscale Surface Patterning in Mexylaminotriazine-Functionalized Molecular Glass Derivatives

et al. 2016

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Nanoscale surface patterns were observed in thin films of mexylaminotriazine-functionalized glasses containing polar groups upon the application of an electric field at temperatures over their glass transition temperatures (Tg). This phenomenon occurred due to the surface deformation process initiated by external electric field instabilities on the films. The minimal surface deformation temperature (Tdewet) relative to Tg was found to increase as a function of the polarity of the substituents and the surface pattern roughness was observed to increase linearly with temperature for a fixed electric field and exposure time. Reversal of the electrical field polarity and the use of both hydrophilic and hydrophobic substrates did not significantly change the surface deformation behavior of the films, which is due to the deposition of charges at the free interface. The application of a mask between the electric field electrodes allowed to selectively pattern areas that are exposed. Furthermore, it was observed that this surface deformation behavior was reversible, since heating the films to a temperature above Tg in the absence of an electric field caused the erasure of all surface patterns.

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Novel 3-D Structures in Polymer Films by Coupling External and Internal Fields

Cited by 51 publications

References 13 publications

3D lithography by rapid curing of the liquid instabilities at nanoscale

3D lithography by rapid curing of the liquid instabilities at nanoscale

Electric field induced microstructures in thin films on physicochemically heterogeneous and patterned substrates

Electric-Field-Induced Nanoscale Surface Patterning in Mexylaminotriazine-Functionalized Molecular Glass Derivatives

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