1
|
Park H, Hwang J, Chae H, Kang DJ. Rapid In-Plane Pattern Growth for Large-Area Inverse Replication Through Electrohydrodynamic Instability of Polymer Films. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400155. [PMID: 38644332 DOI: 10.1002/smll.202400155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 03/25/2024] [Indexed: 04/23/2024]
Abstract
Nanopatterning driven by electrohydrodynamic (EHD) instability can aid in the resolution of the drawbacks inherent in conventional imprinting or other molding methods. This is because EHD force negates the requirement of physical contact and is easily tuned. However, its potential has not examined owing to the limited size of the pattern replica (several to tens of micrometers). Thus, this study proposes a new route for large-area patterning through high-speed evolution of EHD-driven pattern growth along the in-plane axis. Through the acceleration of the in-plane growth, while selectively controlling a specific edge growth, the pattern replica area can be extended from the micro- to centimeter scale with high fidelity. Moreover, even in the case of nonuniform contact mode, the proposed rapid in-plane growth mode facilitates uniform large-scale replication, which is not possible in conventional imprinting or other molding methods.
Collapse
Affiliation(s)
- Hyunje Park
- Research Institute of Basic Sciences, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Jaeseok Hwang
- Wonik IPS Semiconductor Research Center, 75, Jinwisandan-ro, Jinwi-myeon, Pyeongtaek-si, Gyeonggi-do, 17709, Republic of Korea
| | - Heejoon Chae
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Dae Joon Kang
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| |
Collapse
|
2
|
Park H, Hwang J, Lee J, Kang DJ. Rapid Electrohydrodynamic-Driven Pattern Replication over a Large Area via Ultrahigh Voltage Pulses. ACS NANO 2023; 17:22456-22466. [PMID: 37939012 DOI: 10.1021/acsnano.3c05413] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Despite the prospects of electrohydrodynamic instability patterning (EHIP), poor process parameter controllability is a significant challenge in uniform large-scale nanopatterning. Herein, we introduce a EHIP process using an ultrahigh electric field (>108 V/m) to effectively accelerate the pattern growth evolution. Owing to the strong dependence on a temporal parameter (1/τm) of the field strength, our method not only reduces the completion time of pattern growth but also overcomes critical parametric restrictions on the pattern replication, thereby enhancing the replicated pattern quality in three dimensions. The pattern can be uniformly replicated over the entire film surface even without a perfectly uniform air gap, which has been severely difficult in the conventional method. To further demonstrate how straightforward yet versatile our approach is, we applied our EHIP approach to successfully replicate the densely packed nanostructures of cicada wings.
Collapse
Affiliation(s)
- Hyunje Park
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jaeseok Hwang
- Wonik IPS Semiconductor Research Center, 75, Jinwisandan-ro, Jinwi-myeon, Pyeongtaek-si, Gyeonggi-do 17709, Republic of Korea
| | - Jaejong Lee
- Korea Institute of Machinery and Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, Republic of Korea
| | - Dae Joon Kang
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| |
Collapse
|
3
|
Bhatt B, Mukhopadhyay S, Khare K. Frequency-Dependent Dewetting of Thin Liquid Films Using External ac Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13512-13520. [PMID: 37707358 DOI: 10.1021/acs.langmuir.3c01537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The stability of thin liquid films on a surface can be controlled by using external stimuli, such as an electric field, temperature, or light, by manipulating the total excess free energy of the system. It has been previously shown that thin lubricating films on slippery surfaces can be destabilized via the spinodal mechanism using an external electric field, which returns to the original stable configuration upon the electric field. However, the role of the frequency of the applied ac electric field is not clear, which is the main topic of study in this report. When an ac electric field of fixed voltage and varying frequency is applied across thin lubricating films of slippery surfaces, a different dewetting behavior is observed. Characteristic length and time scales of dewetting depend strongly on the frequency of the applied voltage, which is primarily due to the change in the dielectric behavior of the lubricating fluid. In addition, the interplay of various time scales involved in the dewetting process also depends on the frequency.
Collapse
Affiliation(s)
- Bidisha Bhatt
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Soumik Mukhopadhyay
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Krishnacharya Khare
- Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India
| |
Collapse
|
4
|
Samanta A. Modal and nonmodal stability analysis for an electrified falling film. Phys Rev E 2023; 107:045105. [PMID: 37198827 DOI: 10.1103/physreve.107.045105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
We have performed the modal and nonmodal stability analyses of a gravity-driven three-dimensional viscous incompressible fluid flowing over an inclined plane in the presence of a uniform electric field acting normal to the plane at infinity. The time evolution equations are derived for normal velocity, normal vorticity, and fluid surface deformation, respectively, and solved numerically by using the Chebyshev spectral collocation method. The modal stability analysis demonstrates the existence of three unstable regions for the surface mode in the wave number plane at the lower value of the electric Weber number. However, these unstable regions coalesce and magnify as the electric Weber number rises. By contrast, there exists only one unstable region for the shear mode in the wave number plane, which attenuates slightly with an increase in the value of the electric Weber number. But both the surface and shear modes are stabilized in the presence of the spanwise wave number, where the long-wave instability shifts towards the finite wavelength instability as the spanwise wave number rises. On the other hand, the nonmodal stability analysis reveals the existence of transient disturbance energy growth, the maximum value of which intensifies slightly with an increase in the value of the electric Weber number.
Collapse
Affiliation(s)
- Arghya Samanta
- Department of Applied Mechanics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| |
Collapse
|
5
|
Zhang X, Zhai W, Fan L, Kim F, Yu Y. In Situ Electron Microscopy Study of the Dynamics of Liquid Flow in Confined Cells. ACS APPLIED MATERIALS & INTERFACES 2022; 14:28882-28889. [PMID: 35708236 DOI: 10.1021/acsami.2c05494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Confined liquid has attracted great attention due to its potential applications in nanofluidic devices. With the development of liquid-cell transmission electron microscopy (LC-TEM), investigating the behaviors of confined liquid can be realized in real time. However, the dynamics of the liquid layer in liquid cells have not been fully understood. Here, nanoparticles (NPs) adhered to the cell window membranes are used as reference objects to study the flow regime of the liquid layer, which causes cooperative motion of the membranes and the NPs. Two categories of motion behaviors are investigated. One is the contraction of NPs toward the interior viewing area which results from the spreading out of the liquid to the surrounding region, with the bending of the membranes increasing with the loss of liquid in the viewing area. The other motion behavior is the occasional movement of all the NPs in the same direction with the directional movement of the liquid layer. This work offers a new method to study the dynamics of liquids by LC-TEM, the discoveries of which are valuable for understanding the confined liquid dynamics.
Collapse
Affiliation(s)
- Xiuli Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| | - Wenbo Zhai
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| | - Li Fan
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Franklin Kim
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yi Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| |
Collapse
|
6
|
Park H, Hwang J, Lee TH, Lee J, Kang DJ. Fog Collection Based on Secondary Electrohydrodynamic-Induced Hybrid Structures with Anisotropic Hydrophilicity. ACS APPLIED MATERIALS & INTERFACES 2021; 13:27575-27585. [PMID: 34085809 DOI: 10.1021/acsami.1c04761] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The outcomes of the study of plant surfaces, such as rice leaves or bamboo leaves, have led to extensive efforts being devoted to fabricating anisotropic arrays of micro/nanoscale features for exploring anisotropic droplet spreading. Nonetheless, precise engineering of the density and continuity of three-phase contact lines for anisotropic wetting remains a significant challenge without resorting to chemical modifications and costly procedures. In this work, we investigated secondary electrohydrodynamic instability in polymer films for producing secondary nanosized patterns between the micrometer-sized grooves by controlling the timescale parameter, 1/τm (>10-4 s-1). We experimentally demonstrated facile morphological control of anisotropic wettability without the use of any chemical modifications. Thus, anisotropic hydrophilic surfaces fabricated by the secondary phase instability of polymer films are advantageous for both droplet condensation and removal, thereby outperforming the water collection efficiency of conventional (isotropic) hydrophilic surfaces in water harvesting applications (∼200 mg·cm-2·h-1) with excellent durability.
Collapse
Affiliation(s)
- Hyunje Park
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jaeseok Hwang
- Department of Energy Science, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Tae Hyeong Lee
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Jaejong Lee
- Korea Institute of Machinery and Materials (KIMM), 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 34103, Republic of Korea
| | - Dae Joon Kang
- Department of Physics, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| |
Collapse
|
7
|
Hwang J, Park H, Lee J, Kang DJ. Parametric scheme for rapid nanopattern replication via electrohydrodynamic instability. RSC Adv 2021; 11:18152-18161. [PMID: 35480914 PMCID: PMC9033445 DOI: 10.1039/d1ra01728d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/10/2021] [Indexed: 11/21/2022] Open
Abstract
Electrohydrodynamic (EHD) instability patterning exhibits substantial potential for application as a next-generation lithographic technique; nevertheless, its development continues to be hindered by the lack of process parameter controllability, especially when replicating sub-microscale pattern features. In this paper, a new parametric guide is introduced. It features an expanded range of valid parameters by increasing the pattern growth velocity, thereby facilitating reproducible EHD-driven patterning for perfect nanopattern replication. Compared with conventional EHD-driven patterning, the rapid patterning approach not only shortens the patterning time but also exhibits enhanced scalability for replicating small and geometrically diverse features. Numerical analyses and simulations are performed to elucidate the interplay between the pattern growth velocity, fidelity of the replicated features, and boundary between the domains of suitable and unsuitable parametric conditions in EHD-driven patterning. The developed rapid route facilitates nanopattern replication using EHD instability with a wide range of suitable parameters and further opens up many opportunities for device applications using tailor-made nanostructures in an effective and straightforward manner. 1/τm-dependent electrohydrodynamic replication of a hexagonally ordered hole array nanopattern by adjusting the filling ratio. As the 1/τm increases, the morphology evolves into the perfectly replicated hole features with increasing filling ratio.![]()
Collapse
Affiliation(s)
- Jaeseok Hwang
- Department of Energy Science
- Sungkyunkwan University
- Suwon
- Republic of Korea
| | - Hyunje Park
- Department of Physics
- Sungkyunkwan University
- Suwon
- Republic of Korea
| | - Jaejong Lee
- Korea Institute of Machinery and Materials (KIMM)
- Daejeon 34103
- Republic of Korea
| | - Dae Joon Kang
- Department of Physics
- Sungkyunkwan University
- Suwon
- Republic of Korea
| |
Collapse
|
8
|
Roy P, Mukherjee R, Bandyopadhyay D, Gooh Pattader PS. Electrodynamic-contact-line-lithography with nematic liquid crystals for template-less E-writing of mesopatterns on soft surfaces. NANOSCALE 2019; 11:16523-16533. [PMID: 31454013 DOI: 10.1039/c9nr05729c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the development of a single-step, template-less and fast pathway, namely, Electrodynamic-Contact-Line-Lithography (ECLL), to write micro to nanopatterns on the surface of a soft polymer film. As a model system, a layer of nematic liquid crystals (NLC), resting on a polymer thin film, was sandwiched between a pair of electrodes emulating the electrowetting on a dielectric (EWOD) setup. Upon the application of electric field, the Maxwell stresses thus generated at the NLC-polymer interface due to the high dielectric contrast stimulated an unprecedented fingering instability at the advancing NLC-polymer-air contact line. In the process, the advancing electrospreading front of NLC left the footprint of an array of micro to nanoscale wells on the polymer surface with a long-range ordering thus unveiling a pathway for maskless patterning of a soft elastic film. Unlike the conventional electric field induced lithography (EFL), the meso-scale morphology was found to follow the short wavelength-scales as the periodicity of the patterns (λc) varied linearly with the thickness of the film (h), (λc∝h). The high dielectric contrast at the NLC-polymer interface and the local fluctuation of the NLC directors ensured a time scale much faster than the same observed for the polymer-air systems.
Collapse
Affiliation(s)
- Pritam Roy
- Centre for Nanotechnology, Indian Institute of Technology, Guwahati, Assam 781039, India.
| | - Rabibrata Mukherjee
- Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India
| | - Dipankar Bandyopadhyay
- Centre for Nanotechnology, Indian Institute of Technology, Guwahati, Assam 781039, India. and Department of Chemical Engineering, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Partho Sarathi Gooh Pattader
- Centre for Nanotechnology, Indian Institute of Technology, Guwahati, Assam 781039, India. and Department of Chemical Engineering, Indian Institute of Technology, Guwahati, Assam 781039, India
| |
Collapse
|
9
|
Koupaei AM, Nazaripoor H, Sadrzadeh M. Electrohydrodynamic Patterning of Polyethersulfone Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12139-12149. [PMID: 31419149 DOI: 10.1021/acs.langmuir.9b01948] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Microstructuring the surface of membranes is recognized as one of the effective strategies to mitigate the fouling phenomenon. Over the years, significant efforts have been undertaken to develop new techniques for altering the membrane surface topography at the micro- and nanoscale. However, all the previously suggested approaches suffer from some serious drawbacks that impede their widespread implementations, including cost, time, and cumbersomeness. In this study, we show that the electrohydrodynamic (EHD) patterning process can be successfully adopted to form surface patterns on polyethersulfone (PES) microfiltration membranes. The linear stability analysis and nonlinear numerical simulation are performed to theoretically predict the size of the created raised columnar structure (often called pillars). In contrast to the conventional EHD patterning process, the developed method works at room temperature and nonsolvent-induced phase separation is used to solidify the formed structures. An array of pillars was formed on the membrane surface, whose height and width were found to be as low as 31 ± 5 and 98 ± 12 μm, respectively. It is demonstrated that fabricating surface-patterned PES membranes does not require sophisticated facilities and precise control of process condition using this simple moldless method.
Collapse
Affiliation(s)
- Ali Malekpour Koupaei
- Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, Advanced Water Research Lab (AWRL) , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Hadi Nazaripoor
- Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, Advanced Water Research Lab (AWRL) , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Mohtada Sadrzadeh
- Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, Advanced Water Research Lab (AWRL) , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| |
Collapse
|
10
|
Formation of Polymer Walls through the Phase Separation of a Liquid Crystal Mixture Induced by a Spatial Elastic Energy Difference. Sci Rep 2019; 9:10288. [PMID: 31312001 PMCID: PMC6635405 DOI: 10.1038/s41598-019-46810-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 07/05/2019] [Indexed: 12/03/2022] Open
Abstract
We propose a method to form polymer walls without the use of a photomask in a liquid crystal (LC) cell by phase separation of an LC mixture induced by a spatial elastic energy difference. When an in-plane electric field is applied to a vertically aligned cell filled with a mixture of LC and a reactive monomer (RM), a high spatial elastic energy is induced along the direction perpendicular to the interdigitated electrodes. RMs move to the boundaries where the elastic energy is very high and an in-plane component of the applied electric field exists, which results in the phase separation of the LC/RM mixture. We have shown that we can form polymer walls by applying ultraviolet light irradiation to the LC cell. These polymer walls can function as alignment layers. We observed morphological patterns of the polymer structure through polarized optical microscopy, scanning electron microscopy, and atomic force microscopy. The polymer walls formed in an LC cell can affect the orientation of LCs in the lateral direction. Bistable switching of a polymer-walled cell could be achieved by using three-terminal electrodes where both vertical and in-plane electric fields can be applied. Vertical anchoring with the alignment layer on each substrate allows LC molecules to remain vertically aligned after removal of the applied vertical electric field. Furthermore, in-plane anchoring with the formed polymer walls allows the LC molecules to remain homogeneously aligned after removal of the applied in-plane electric field. The proposed method for the formation of polymer structures could be a useful tool to fabricate LC cells for various applications. As a bistable phase-grating device, the diffraction efficiency of a polymer-walled cell was comparable to that of a pure-LC cell. Its operating voltage was 44% lower than that of a pure-LC cell owing to in-plane anchoring provided by the polymer walls. Moreover, it can be operated with very low power because it does not require power to maintain the state. In addition, the total response time of a polymer-walled cell was approximately 68% shorter than that of a pure-LC cell because all switching was forcibly controlled by applying an electric field.
Collapse
|
11
|
Sahoo S, Bhandaru N, Mukherjee R. Reversible morphological switching and deformation hysteresis in electric field mediated instability of thin elastic films. SOFT MATTER 2019; 15:3828-3834. [PMID: 30993267 DOI: 10.1039/c8sm02622j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Reversible morphology switching in a soft elastic film sandwiched between two parallel electrodes when subject to an externally applied electric field is reported herein. In contrast to electric field mediated instability of a thin liquid film, where the instability patterns remain permanent, in the present case the patterns debond completely or partially when the electric field is switched off, depending on whether the gap spacing (dG) between the film and the top electrode is >100 nm or not. The onset of instability is marked with the appearance of isotropic columns when the applied field strength (U) exceeds a critical value (Uc). The subsequent increase in U leads to the gradual transition of the instability patterns from pillars to bi-continuous labyrinths to an array of holes. Complete conformal contact is established between the film and the top electrode at U = UF. When U is reduced, the morphology changes in a reverse sequence. There is a significant level of hysteresis between the bonding and debonding stages, including persistence of the features at much lower voltages due to pinning of the patterns to the top electrode. Complete detachment occurs at a lower voltage UD when dG > 100 nm. The holes fluctuate before complete contact between the film and the top electrode due to competition between the destabilizing electric field and restoring forces due to stretching of the crosslinked polymer matrix.
Collapse
Affiliation(s)
- Sumita Sahoo
- Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, West Bengal 721302, India.
| | | | | |
Collapse
|
12
|
Cheng PT, Zhou W, Yang F, Lee S. Growth of Polystyrene Pillars in Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4966-4975. [PMID: 30875470 DOI: 10.1021/acs.langmuir.9b00207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surface patterning on polymer films, which is a self-assembly process under the action of external and/or internal impetus, has a variety of applications, including drug delivery and flexible electronics. In this work, we study the growth of polystyrene pillars in the electric field for different combinations of annealing temperature, film thickness, and electrode separation (electric field intensity). There are five stages for the growth of the polystyrene pillars for all the configurations used in this work, including a nucleation stage, a linear growth stage, an acceleration stage in the pillar length prior to the contact between the top surface of a pillar and the upper electrode, a radial growth stage after the contact, and a stationary stage without further growth of the pillar. In the linear growth stage, there exist linear relationships between the pillar length and the annealing time and between the square of the pillar diameter and the annealing time. The activation energies for the rate processes controlling the radial growth and the length growth in the linear growth stage are 30.2 and 25.3 kJ/mol, respectively. There are two rate processes controlling the radial growth of the pillars: one is the field-induced flow of polymer through the polymer film to the roots of pillars and the other is the coalescence of pillars. The activation energy for the coalescence is 16.5 kJ/mol. The results obtained in this work offer a practical route to control the geometrical dimensions of polymer pillars through the processing parameters.
Collapse
Affiliation(s)
- Pai-Ting Cheng
- Department of Materials Science and Engineering , National Tsing Hua University , 101, Kuang Fu Road, 2nd Section , Hsinchu 300 , Taiwan
| | - Wenxiao Zhou
- Department of Mechanical Engineering , University of Rochester , 235 Hopeman Building , Rochester , New York 14604 , United States
| | - Fuqian Yang
- Materials Program, Department of Chemical and Materials Engineering , University of Kentucky , 177 FPAT , Lexington , Kentucky 40506 , United States
| | - Sanboh Lee
- Department of Materials Science and Engineering , National Tsing Hua University , 101, Kuang Fu Road, 2nd Section , Hsinchu 300 , Taiwan
| |
Collapse
|
13
|
Giri A, Kar S. Unraveling the diverse nature of electric field induced spatial pattern formation in Gray-Scott model. J Chem Phys 2019; 150:094904. [PMID: 30849881 DOI: 10.1063/1.5080553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We have considered a Gray-Scott kind of model chemical reaction-diffusion system that comprises ionic reactants and auto-catalysts to investigate the possibilities of mobility induced spatial pattern formation under the influence of an external electric field. Our study reveals that applying a uni-directional electric field can deform the already existing Turing patterns obtained due to diffusion driven instability, but cannot produce mobility driven instability and consequent spatial patterns in the absence of diffusion driven instability for a Gray-Scott like system. However, application of the electric field along two mutually perpendicular directions produces a mobility induced pattern in the absence of any differences in the diffusivities of the corresponding chemical reactants. Additionally, we have shown a systematic way to predict the range of absolute values of the pair of electric field intensities along two directions that will lead to spatially heterogeneous patterns in the absence of diffusion driven instability. Our study further demonstrates that the stability of the patterns formed and the nature of the patterns evolved varies with the increasing level of electric field intensities. The insights gained from this study will allow us to develop future experimental strategies to produce diverse range of stable and unique spatial patterns.
Collapse
Affiliation(s)
- Amitava Giri
- Department of Chemistry, IIT Bombay, Powai, Mumbai 400076, India
| | - Sandip Kar
- Department of Chemistry, IIT Bombay, Powai, Mumbai 400076, India
| |
Collapse
|
14
|
Choi TH, Do SM, Jeon BG, Yoon TH. Low-power control of haze using a liquid-crystal phase-grating device with two-dimensional polymer walls. OPTICS EXPRESS 2019; 27:3014-3029. [PMID: 30732329 DOI: 10.1364/oe.27.003014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/29/2018] [Indexed: 06/09/2023]
Abstract
We propose a two-dimensional (2D) polymer-walled liquid-crystal (LC) phase-grating device, which can be used to control the haze with a very low power. 2D polymer walls can be formed in an LC cell through ultraviolet light irradiation while applying an in-plane electric field through phase separation induced by the spatial elastic energy difference. The transparent and translucent states can be realized by applying vertical and in-plane electric fields to the 2D polymer-walled LC cell, respectively. The cell can be operated with a very low power as the transparent [translucent] state is maintained even after the applied vertical [in-plane] electric field is removed. It consumes power only during state switching. The fabricated device exhibits outstanding performances, such as a very low operating voltage (< 10 V), low haze (< 2%) in the transparent state, high haze (> 90%) in the translucent state, and short switching time (< 2 ms), compared to those of other bistable LC devices, which can be used to control the haze.
Collapse
|
15
|
Nazaripoor H, Koch CR, Sadrzadeh M. Ordered high aspect ratio nanopillar formation based on electrical and thermal reflowing of prepatterned thin films. J Colloid Interface Sci 2018; 530:312-320. [PMID: 29982023 DOI: 10.1016/j.jcis.2018.06.080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 11/18/2022]
Abstract
Creating well-ordered, submicron-sized pillars have been stated as main limitation for electrically induced patterning of nanofilms (thickness <100 nm) [1]. In our previous works, it was shown that the aspect ratio of formed nanopillars was increased to about 0.35 when thermocapillary induced instabilities (Thermally Induced Patterning, TIP) is combined with electrodynamics instabilities (Electrically Induced Patterning, EIP). However, further reduction of pillar size resulted in a coarse and randomly distributed pillars [2,3]. Here, the reflowing of initially prepatterned nanofilms are examined in the EIP and combined EIP-TIP process to create a well-ordered and high aspect ratio nanopillar arrays without sacrificing the fidelity of the final structure. The long-wave approximation is used to simplify the governing equations and boundary conditions leading to a fourth order nonlinear partial differential equation called thin film equation that describes the spatio-temporal evolution of the interface. The mechanism of pattern reflowing is discussed for both linear (initial) and nonlinear (long-term) deformations in EIP and EIP-TIP process. The optimum initial pattern width, height and the center-to-center distance is found based on the characteristic wavelength for growth of instabilities predicted by linear stability analysis and nonlinear simulation results.
Collapse
Affiliation(s)
- Hadi Nazaripoor
- Advanced Water Research Lab (AWRL), Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada
| | - Charles R Koch
- Advanced Water Research Lab (AWRL), Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada
| | - Mohtada Sadrzadeh
- Advanced Water Research Lab (AWRL), Department of Mechanical Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.
| |
Collapse
|
16
|
Lahiri A, Behrens N, Pulletikurthi G, Yochelis A, Kroke E, Cui T, Endres F. Electrochemically induced phase separation and in situ formation of mesoporous structures in ionic liquid mixtures. SCIENCE ADVANCES 2018; 4:eaau9663. [PMID: 30397654 PMCID: PMC6203224 DOI: 10.1126/sciadv.aau9663] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/19/2018] [Indexed: 06/08/2023]
Abstract
Liquid-liquid phase separation is mainly dependent on temperature and composition. Electric fields have also been shown to influence demixing of binary liquid mixtures. However, a puzzling behavior that remains elusive is the electric field-induced phase separation in ion-containing solvents at low voltages, as predicted by Tsori and Leibler. Here, we report the first experimental study of such a phenomenon in ionic liquid-silane mixtures, which not only results in phase separation at the electrode-electrolyte interface (EEI) but also is accompanied by deposition of porous structures of micrometer size on the electrode. This multiscale phenomenon at the EEI was found to be triggered by an electrochemically induced process. Using several analytical methods, we reveal the involved mechanism in which the formation of new Si-N bonds becomes unstable and eventually decomposes into the formation of silane-rich and silane-poor phases. The deposition of porous structures on the electrode surface is therefore a realization of the silane-rich phase. The finding of an electrochemically induced phase separation not only brings a paradigm shift in understanding the EEI in ionic liquids but also provides alternative strategies toward designing porous surfaces.
Collapse
Affiliation(s)
- Abhishek Lahiri
- Institute of Electrochemistry, Clausthal University of Technology, Arnold Sommerfeld Str. 6, D-38678, Clausthal-Zellerfeld, Germany
| | - Niklas Behrens
- Institute of Electrochemistry, Clausthal University of Technology, Arnold Sommerfeld Str. 6, D-38678, Clausthal-Zellerfeld, Germany
| | - Giridhar Pulletikurthi
- Institute of Electrochemistry, Clausthal University of Technology, Arnold Sommerfeld Str. 6, D-38678, Clausthal-Zellerfeld, Germany
| | - Arik Yochelis
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel
- Department of Physics, Ben-Gurion University of the Negev, Be’er Sheva 8410501, Israel
| | - Edwin Kroke
- Institute of Inorganic Chemistry, Technische Universität Bergakademie Freiberg, D-09599 Freiberg, Germany
| | - Tong Cui
- Institute of Electrochemistry, Clausthal University of Technology, Arnold Sommerfeld Str. 6, D-38678, Clausthal-Zellerfeld, Germany
| | - Frank Endres
- Institute of Electrochemistry, Clausthal University of Technology, Arnold Sommerfeld Str. 6, D-38678, Clausthal-Zellerfeld, Germany
| |
Collapse
|
17
|
Dwivedi S, Narayanan R, Chaudhary R, Mukherjee R, Atta A. Controlled Nanoscale Electrohydrodynamic Patterning Using Mesopatterned Template. ACS OMEGA 2018; 3:9781-9789. [PMID: 31459107 PMCID: PMC6644543 DOI: 10.1021/acsomega.8b01319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/09/2018] [Indexed: 06/09/2023]
Abstract
We report the path for a possible fabrication of an array of nanogrooves, by electro-hydrodynamic instability-mediated patterning of a thin polymer film using a patterned stamp with much larger features. Using a predictive computational model based on finite element method, we find the route to control the coalescence of initial instabilities that arise with the onset of spatially varying DC electric field generated through topographical patterns in the top electrode. These quasi-steady structures are shown to evolve with the electrostatic and geometric nature of the two-electrode system and are of a stable intermediate during the process of feature replication, under each electrode feature. We identify conditions to obtain nanogrooves for a range of operating conditions. Such simulations are likely to guide experiments, where simultaneous optimization of multiple parameters to fabricate features with lateral dimension smaller than that of the electrode patterns is challenging.
Collapse
Affiliation(s)
- Swarit Dwivedi
- Multiscale
Computational Fluid Dynamics Laboratory, Department of Chemical Engineering, and Instability
and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Raj Narayanan
- Multiscale
Computational Fluid Dynamics Laboratory, Department of Chemical Engineering, and Instability
and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Rahul Chaudhary
- Multiscale
Computational Fluid Dynamics Laboratory, Department of Chemical Engineering, and Instability
and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Rabibrata Mukherjee
- Multiscale
Computational Fluid Dynamics Laboratory, Department of Chemical Engineering, and Instability
and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| | - Arnab Atta
- Multiscale
Computational Fluid Dynamics Laboratory, Department of Chemical Engineering, and Instability
and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302, India
| |
Collapse
|
18
|
Ghosh A, Bandyopadhyay D, Sharma A. Electric field mediated elastic contact lithography of thin viscoelastic films for miniaturized and multiscale patterns. SOFT MATTER 2018; 14:3963-3977. [PMID: 29736548 DOI: 10.1039/c8sm00428e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Elastic contact lithography (ECL) and electric field lithography (EFL) have both shown significant potential to develop large-area micropatterns on polymeric surfaces. Recently, the major challenges associated with these processes have been the improvement of the aspect ratio and reduction in the size and periodicity of the patterns fabricated. Herein, with the help of non-linear simulations, we show that combining these methods can be one recipe to overcome these limitations. We consider a linear viscoelastic film for the linear and non-linear analyses. In this regard, we explore the role of the moving contactor to improve the aspect ratio of the patterns. The study uncovers that (i) combined destabilizing influences originating from van der Waals and electric field forces ensure smaller timescales and length scales for the instabilities, (ii) the aid from the electric field helps to improve the minimum separation distance so that the contact instability initiates at a larger separation distance, (iii) a long-range ordering can be inflicted on the patterns on the polymer surfaces when electrodes with periodic physicochemical patterns are used and (iv) the strength of the externally applied electric field and the ratio of elastic to viscous compliance of the film play crucial roles in deciding the different modes of debonding of the film - peeling, catastrophic or coalescence. The proposed method can improve the aspect ratio of patterns by ∼9-fold during the peeling mode of debonding. Furthermore, pathways to develop technologically important biomimetic surfaces with multiscale and hierarchical structures have been shown.
Collapse
Affiliation(s)
- Abir Ghosh
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India.
| | | | | |
Collapse
|
19
|
Boudoire F, Partel S, Toth R, Heier J. Combining parallel pattern generation of electrohydrodynamic lithography with serial addressing. RSC Adv 2018; 8:30932-30936. [PMID: 35548741 PMCID: PMC9085484 DOI: 10.1039/c8ra06160b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/27/2018] [Indexed: 11/28/2022] Open
Abstract
Electrohydrodynamic lithography (EHDL) is a parallel patterning process which typically makes use of topographically structured electrodes to guide pattern formation along areas of higher electrical field strength. The main driving force for pattern formation is an electrostatic pressure acting on a thin film polymer surface caused by a voltage applied between a top and bottom electrode. We here demonstrate that the principle can be applied using an addressable electrode composed of interdigitated fingers. Depending on the applied voltages, line patterns with different periodicities were fabricated. Our proof-of-concept experiments pave the way for a parallel pattern replication process where a serially addressed master is used. We complement the experiments by modelling the potentials across the electrodes and electrostatic forces acting on the polymer surface using different addressing schemes. Numerical simulations of the experimental setup pointed to some critical issues we experienced during the design of the experiments. Via different electrode addressing schemes in electrohydrodynamic lithography, different patterns were generated.![]()
Collapse
Affiliation(s)
- F. Boudoire
- Empa
- Swiss Federal Laboratories for Materials Science and Technology
- Laboratory for Functional Polymers
- Switzerland
- Empa
| | - S. Partel
- Vorarlberg University of Applied Sciences
- 6850 Dornbirn
- Austria
| | - R. Toth
- Empa
- Swiss Federal Laboratories for Materials Science and Technology
- Laboratory for High Performance Ceramics
- Switzerland
| | - J. Heier
- Empa
- Swiss Federal Laboratories for Materials Science and Technology
- Laboratory for Functional Polymers
- Switzerland
| |
Collapse
|
20
|
Nazaripoor H, Koch CR, Sadrzadeh M. Enhanced Electrically Induced Micropatterning of Confined Thin Liquid Films: Thermocapillary Role and Its Limitations. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b02814] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hadi Nazaripoor
- Department of Mechanical
Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Charles R. Koch
- Department of Mechanical
Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Mohtada Sadrzadeh
- Department of Mechanical
Engineering, 10-367 Donadeo Innovation Center for Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| |
Collapse
|
21
|
Trease CH, Foot PJ, Augousti AT. Electrohydrodynamic patterning in a curable resin over a wide range of fabrication parameters. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
22
|
Jones AR, Kim CB, Zhou SX, Ha H, Katsumata R, Blachut G, Bonnecaze RT, Ellison CJ. Generating Large Thermally Stable Marangoni-Driven Topography in Polymer Films by Stabilizing the Surface Energy Gradient. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Amanda R. Jones
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Chae Bin Kim
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Sunshine X. Zhou
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Heonjoo Ha
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Reika Katsumata
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Gregory Blachut
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Roger T. Bonnecaze
- McKetta
Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Stop C0400, Austin, Texas 78712, United States
| | - Christopher J. Ellison
- Department
of Chemical Engineering and Materials Science, The University of Minnesota—Twin Cities, 421 Washington Ave SE Rm 151, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
23
|
Tian H, Shao J, Chen X, Jiang W, Wang L, Ding Y. Investigation of the role of template features on the electrically induced structure formation (EISF) for a faithful duplication. Electrophoresis 2017; 38:1105-1112. [PMID: 28306173 DOI: 10.1002/elps.201700032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/10/2017] [Accepted: 03/10/2017] [Indexed: 12/12/2022]
Abstract
Electrically induced structure formation, as a physical approach to fabricate micro/nanostructures, has attracted much attention because of the simple process, low-cost, high-efficiency, and wide applications on electronics, microfluidics, and so forth. Hitherto, the influence of some process parameters, such as voltage, air gap, film thickness, polymer properties, on the polymeric behavior, and the structure formation has been explored, neglecting the effects of the template features, which affect the polymer deformation. Especially for the conductive protrusions directly contacting the polymer, the phenomenon of electric breakdown may occur, leading to a failure of structure formation. The limitation of the research on the template features triggers the necessity to study its influence for a faithful deformation. In this paper, three types of patterned template are studied based on the electric field at the air-polymer interface, consisting of completely conductive template, partially conductive template, and dielectric template. Comprehensive consideration of the electric intensity for a sufficient driving pressure and the leaky current for preventing damaging the polymer, some guiding opinions on the template material and geometry can be provided to design the patterned template for the electrically induced structure formation process with a purpose for a faithful structure.
Collapse
Affiliation(s)
- Hongmiao Tian
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China.,Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha, P. R. China
| | - Jinyou Shao
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Xiaoliang Chen
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Wei Jiang
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Li Wang
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China
| | - Yucheng Ding
- Micro- and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China
| |
Collapse
|
24
|
Guo Y, Chen Y, Wang E, Cakmak M. Roll-to-Roll Continuous Manufacturing Multifunctional Nanocomposites by Electric-Field-Assisted "Z" Direction Alignment of Graphite Flakes in Poly(dimethylsiloxane). ACS APPLIED MATERIALS & INTERFACES 2017; 9:919-929. [PMID: 27982568 DOI: 10.1021/acsami.6b13207] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A roll-to-roll continuous process was developed to manufacture large-scale multifunctional poly(dimethylsiloxane) (PDMS) films embedded with thickness direction ("Z" direction) aligned graphite nanoparticles by application of electric field. The kinetics of particle "Z" alignment and chain formation was studied by tracking the real-time change of optical light transmission through film thickness direction. Benefiting from the anisotropic structure of aligned particle chains, the electrical and thermal properties of the nanocomposites were dramatically enhanced through the thickness direction as compared to those of the nanocomposites containing the same particle loading without electrical field alignment. With 5 vol % graphite loading, 250 times higher electrical conductivity, 43 times higher dielectric permittivity, and 1.5 times higher thermal conductivity was achieved in the film thickness direction after the particles were aligned under electrical field. Moreover, the aligned nanocomposites with merely 2 vol % graphite particles exhibit even higher electric conductivity and dielectric permittivity than those of the nonaligned nanocomposites at random percolation threshold (10 vol % particles), as the "electric-field-directed" percolation threshold concentration is substantially decreased using this process. As the graphite loading increases to 20 vol %, the aligned nanocomposites exhibit thermal conductivity as high as 6.05 W/m·K, which is 35 times the thermal conductivity of pure matrix. This roll-to-roll electric field continuous process provides a simple, low-cost, and commercially viable method to manufacture multifunctional nanocomposites for applications as embedded capacitor, electromagnetic (EM) shielding, and thermal interface materials.
Collapse
Affiliation(s)
- Yuanhao Guo
- Department of Polymer Engineering, University of Akron , Akron, Ohio 44325, United States
| | - Yuwei Chen
- Department of Polymer Engineering, University of Akron , Akron, Ohio 44325, United States
- Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science & Technology , Qingdao 266042, China
| | - Enmin Wang
- Department of Polymer Engineering, University of Akron , Akron, Ohio 44325, United States
| | - Miko Cakmak
- Department of Polymer Engineering, University of Akron , Akron, Ohio 44325, United States
- School of Materials Engineering, School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States
| |
Collapse
|
25
|
Li H, Yu W, Wang T, Liu Z, Desmulliez MPY. Numerical study of the faithful replication of micro/nanostructures on curved surfaces by the electrohydrodynamic instability process. Electrophoresis 2016; 38:525-532. [PMID: 27862080 DOI: 10.1002/elps.201600192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 10/09/2016] [Accepted: 11/02/2016] [Indexed: 11/06/2022]
Abstract
This paper reports the numerical study of the one-step faithful replication of micro/nano-scale structures on a fiber surface by using the electrohydrodynamic instability patterning (EHDIP) process. By employing a rigorous numerical analysis method, conditions are revealed under which the faithful replication of a pattern can be achieved from a curved master electrode. It is found that the radius of curvature of the fiber plays an important role in determining the final morphology of the pattern when the destabilizing electric field is dominant in both the flat and patterned template cases. In general, stronger electric fields and larger radii of curvature of the substrate are favorable for the faithful replication of the pattern. In addition, theoretical analysis shows that higher aspect ratio of micro/nanostructures can be obtained on curved surfaces by using a master with a much lower aspect ratio. The results demonstrated in this study aims to provide guidelines for the faithful fabrication of micro/nanostructures on curved surfaces by the EHDIP process.
Collapse
Affiliation(s)
- Hefu Li
- School of Physical Science and Information Technology, Liaocheng University, Liaocheng, P. R. China
| | - Weixing Yu
- Key Laboratory of Spectral Imaging Technology, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xian, P. R. China
| | - Taisheng Wang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics & Physics, Chinese Academy of Sciences, Changchun, P. R. China
| | - Zhenyu Liu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics & Physics, Chinese Academy of Sciences, Changchun, P. R. China
| | - M P Y Desmulliez
- MIcroSystems Engineering Centre (MISEC), Institute of Signals, Sensors and Systems, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, UK
| |
Collapse
|
26
|
Corson LT, Mottram NJ, Duffy BR, Wilson SK, Tsakonas C, Brown CV. Dynamic response of a thin sessile drop of conductive liquid to an abruptly applied or removed electric field. Phys Rev E 2016; 94:043112. [PMID: 27841646 DOI: 10.1103/physreve.94.043112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 06/06/2023]
Abstract
We consider, both theoretically and experimentally, a thin sessile drop of conductive liquid that rests on the lower plate of a parallel-plate capacitor. We derive analytical expressions for both the initial deformation and the relaxation dynamics of the drop as the electric field is either abruptly applied or abruptly removed, as functions of the geometrical, electrical, and material parameters, and investigate the ranges of validity of these expressions by comparison with full numerical simulations. These expressions provide a reasonable description of the experimentally measured dynamic response of a drop of conductive ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate.
Collapse
Affiliation(s)
- L T Corson
- Department of Mathematics & Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, United Kingdom
| | - N J Mottram
- Department of Mathematics & Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, United Kingdom
| | - B R Duffy
- Department of Mathematics & Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, United Kingdom
| | - S K Wilson
- Department of Mathematics & Statistics, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, United Kingdom
| | - C Tsakonas
- School of Science & Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | - C V Brown
- School of Science & Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
| |
Collapse
|
27
|
Yang Q, Li BQ, Tian H, Li X, Shao J, Chen X, Xu F. Deformation Hysteresis of Electrohydrodynamic Patterning on a Thin Polymer Film. ACS APPLIED MATERIALS & INTERFACES 2016; 8:17668-17675. [PMID: 27326791 DOI: 10.1021/acsami.6b04192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electrohydrodynamic patterning is a technique that enables micro/nanostructures via imposing an external voltage on thin polymer films. In this investigation, we studied the electrohydrodynamic patterning theoretically and experimentally, with special interest focused on the equilibrium state. It is found that the equilibrium structure height increases with the voltage. In addition, we have observed, and believe it to be the first time, a hysteresis phenomenon exists in the relationship between the voltage and structure height. With an increase in the voltage, a critical value (the first critical voltage) is noticed, above which the polymer film would increase dramatically until it comes into contact with the template. However, with a decrease in the voltage, a smaller voltage (the second critical voltage) is needed to detach the polymer from the template. The mismatch of the first and second critical voltages distorts the voltage-structure height curve into an "S" shape. Such a phenomenon is verified for three representative templates and also by experiments. Furthermore, the effects of some parameters (e.g., polymer film thickness and dielectric constant) on this hysteresis phenomenon are also discussed.
Collapse
Affiliation(s)
| | - Ben Q Li
- Department of Mechanical Engineering, University of Michigan-Dearborn , Dearborn, Michigan 48128, United States
| | | | | | | | | | | |
Collapse
|
28
|
Tian H, Shao J, Hu H, Wang L, Ding Y. Generation of Hierarchically Ordered Structures on a Polymer Film by Electrohydrodynamic Structure Formation. ACS APPLIED MATERIALS & INTERFACES 2016; 8:16419-16427. [PMID: 27268135 DOI: 10.1021/acsami.6b03406] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The extensive applications of hierarchical structures in optoelectronics, micro/nanofluidics, energy conservation, etc., have led to the development of a variety of approaches for their fabrication, which can be categorized as bottom-up or top-down strategies. Current bottom-up and top-down strategies bear a complementary relationship to each other due to their processing characteristics, i.e., the advantages of one method correspond to the disadvantages of the other, and vice versa. Here we propose a novel method based on electrohydrodynamic structure formation, aimed at combining the main advantages of the two strategies. The method allows the fabrication of a hierarchically ordered structure with well-defined geometry and high mechanical durability on a polymer film, through a simple and low-cost process also suitable for mass-production. In this approach, upon application of an electric field between a template and a substrate sandwiching an air gap and a polymer film, the polymer is pulled toward the template and further flows into the template cavities, resulting in a hierarchical structure with primary and secondary patterns determined by electrohydrodynamic instability and by the template features, respectively. In this work, the fabrication of a hierarchical structure by electrohydrodynamic structure formation is studied using numerical simulations and experimental tests. The proposed method is then employed for the one-step fabrication of a hierarchical structure exhibiting a gradual transition in the periodicity of the primary structure using a slant template and a flat polymer film, which presents an excellent performance on controllable wettability.
Collapse
Affiliation(s)
- Hongmiao Tian
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an, 710049, P. R. China
| | - Jinyou Shao
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an, 710049, P. R. China
| | - Hong Hu
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an, 710049, P. R. China
| | - Li Wang
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an, 710049, P. R. China
| | - Yucheng Ding
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an, 710049, P. R. China
| |
Collapse
|
29
|
Nazaripoor H, Koch CR, Sadrzadeh M, Bhattacharjee S. Thermo-Electrohydrodynamic Patterning in Nanofilms. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5776-5786. [PMID: 27224738 DOI: 10.1021/acs.langmuir.6b01810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
To improve the electrically assisted patterning process and create smaller sized features with the higher active surface area, the combined thermocapillary-electrohydrodynamic (TC-EHD) instability of liquid nanofilms is considered. First, the 3-D thin film equation is rederived for nonisothermal films and then the influential factors on the dynamics and stability of thin liquid film are found using linear stability (LS) analysis. Nonlinear studies are also conducted to investigate the long-time evolution of the interface using an in-house developed Fortran code employing high order finite difference and adaptive time step solver for the spatial and time derivatives. The number density of pillars (columnar raised structure) formed in 1 μm(2) area is significantly increased compared to the EHD base-case and nanosized pillars are created due to the thermocapillary effects. Relative interface area increases of up to 18% due to this pattern miniaturization are realized. It is also found that increase in the thermal conductivity ratio of layers changes the mechanism of pattern formation resulting in nonuniform and randomly distributed micro pillars being generated.
Collapse
Affiliation(s)
- Hadi Nazaripoor
- Department of Mechanical Engineering, 10-232 Donadeo Innovation Center for Engineering, University of Alberta , Edmonton, Alberta Canada . T6G 1H9
| | - Charles R Koch
- Department of Mechanical Engineering, 10-232 Donadeo Innovation Center for Engineering, University of Alberta , Edmonton, Alberta Canada . T6G 1H9
| | - Mohtada Sadrzadeh
- Department of Mechanical Engineering, 10-232 Donadeo Innovation Center for Engineering, University of Alberta , Edmonton, Alberta Canada . T6G 1H9
| | - Subir Bhattacharjee
- Water Planet Engineering, 721 Glasgow Ave, Unit D, Inglewood, California 90301, United States
| |
Collapse
|
30
|
Peng JS, Yang F, Chiang D, Lee S. Kinetics of Field-Induced Surface Patterns on PMMA. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:4602-4609. [PMID: 27094160 DOI: 10.1021/acs.langmuir.6b01304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A simple model was developed to analyze the growth of a liquid pillar under the action of an electric field between two parallel electrodes. A quadratic relationship between time and the diameter of the pillar was obtained. The diameter of the pillar increases with time. Large electric field assists the growth of the liquid pillar, while a liquid with a large viscosity hinders the growth of the liquid pillar. The field-induced formation and growth of PMMA pillars on PMMA films were observed using the configuration of a parallel capacitor. Pillars of larger sizes and smaller densities were formed on thicker PMMA films than on thinner PMMA films. The root-mean-square ( https://en.wikipedia.org/wiki/Root_mean_square ) diameter of the pillars increases with the increase of the annealing time and annealing temperature. The growth behavior of the pillars can be described by an Arrhenius relation with an activation energy of 24.4 kJ/mol, suggesting that the growth of the pillars is controlled by a thermal activation process.
Collapse
Affiliation(s)
- Jyun-Siang Peng
- Department of Materials Science and Engineering National Tsing Hua University , Hsinchu 300, Taiwan
| | - Fuqian Yang
- Department of Chemical and Materials Engineering University of Kentucky , Lexington, Kentucky 40506, United States
| | - Donyau Chiang
- Instrument Technology Research Center, National Applied Research Laboratories , Hsinchu 30076, Taiwan
| | - Sanboh Lee
- Department of Materials Science and Engineering National Tsing Hua University , Hsinchu 300, Taiwan
| |
Collapse
|
31
|
Nazaripoor H, Koch CR, Sadrzadeh M, Bhattacharjee S. Compact micro/nano electrohydrodynamic patterning: using a thin conductive film and a patterned template. SOFT MATTER 2016; 12:1074-1084. [PMID: 26574883 DOI: 10.1039/c5sm02258d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The influence of electrostatic heterogeneity on the electric-field-induced destabilization of thin ionic liquid (IL) films is investigated to control spatial ordering and to reduce the lateral dimension of structures forming on the films. Commonly used perfect dielectric (PD) films are replaced with ionic conductive films to reduce the lateral length scales to a sub-micron level in the EHD pattering process. The 3-D spatiotemporal evolution of a thin IL film interface under homogenous and heterogeneous electric fields is numerically simulated. Finite differences in the spatial directions using an adaptive time step ODE solver are used to solve the 2-D nonlinear thin film equation. The validity of our simulation technique is determined from close agreement between the simulation results of a PD film and the experimental results in the literature. Replacing the flat electrode with the patterned one is found to result in more compact and well-ordered structures particularly when an electrode with square block protrusions is used. This is attributed to better control of the characteristic spatial lengths by applying a heterogeneous electric field by patterned electrodes. The structure size in PD films is reduced by a factor of 4 when they are replaced with IL films, which results in nano-sized features with well-ordered patterns over the domain.
Collapse
Affiliation(s)
- Hadi Nazaripoor
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, CanadaT6G2G8.
| | - Charles R Koch
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, CanadaT6G2G8.
| | - Mohtada Sadrzadeh
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, CanadaT6G2G8.
| | - Subir Bhattacharjee
- Water Planet Engineering, 721 Glasgow Ave, Unit D, Inglewood, California 90301, USA
| |
Collapse
|
32
|
Liu M, Li H, Yu W, Wang T, Liu Z, Desmulliez MPY. Influence of electrode types on the electrohydrodynamic instability patterning process: a comparative study. RSC Adv 2016. [DOI: 10.1039/c6ra05596f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A polymer film resting on a planar substrate under the influence of a electric field. (A) A conductive patterned electrode. (B) A conductive pattern on a dielectric substrate.
Collapse
Affiliation(s)
- Minzhe Liu
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun
| | - Hefu Li
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun
| | - Weixing Yu
- Key Laboratory of Spectral Imaging Technology
- Xi'an Institute of Optics and Precision Mechanics
- Chinese Academy of Sciences
- Xian 710119
- P. R. China
| | - Taisheng Wang
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun
| | - Zhenyu Liu
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun
| | - Marc. P. Y. Desmulliez
- MIcroSystems Engineering Centre (MISEC)
- School of Engineering & Physical Sciences
- Heriot-Watt University
- Edinburgh EH14 4AS
- UK
| |
Collapse
|
33
|
Mukherjee R, Sharma A. Instability, self-organization and pattern formation in thin soft films. SOFT MATTER 2015; 11:8717-8740. [PMID: 26412507 DOI: 10.1039/c5sm01724f] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The free surface of a thin soft polymer film is often found to become unstable and self-organizes into various meso-scale structures. In this article we classify the instability of a thin polymer film into three broad categories, which are: category 1: instability of an ultra-thin (<100 nm) viscous film engendered by amplification of thermally excited surface capillary waves due to interfacial dispersive van der Waals forces; category 2: instability arising from the attractive inter-surface interactions between the free surface of a soft film exhibiting room temperature elasticity and another rigid surface in its contact proximity; and category 3: instability caused by an externally applied field such as an electric field or a thermal gradient, observed in both viscous and elastic films. We review the salient features of each instability class and highlight how characteristic length scales, feature morphologies, evolution pathways, etc. depend on initial properties such as film thickness, visco-elasticity (rheology), residual stress, and film preparation conditions. We emphasize various possible strategies for aligning and ordering of the otherwise isotropic structures by combining the essential concepts of bottom-up and top-down approaches. A perspective, including a possible future direction of research, novelty and limitations of the methods, particularly in comparison to the existing patterning techniques, is also presented for each setting.
Collapse
Affiliation(s)
- Rabibrata Mukherjee
- Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, 721 302, India.
| | - Ashutosh Sharma
- Department of Chemical Engineering and Nano-science Center, Indian Institute of Technology, Kanpur, 208016, India.
| |
Collapse
|
34
|
McEnnis K, Dinsmore AD, Russell TP. Solid particles adsorbed on capillary-bridge-shaped fluid polystyrene surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5299-5305. [PMID: 25938879 DOI: 10.1021/acs.langmuir.5b00372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Particles adsorbed on microscopic polystyrene (PS) capillary bridge surfaces were observed to investigate their motion under capillary forces arising from a nonuniform shape. Capillary bridges were created by placing thin PS films, heated above the glass transition temperature (Tg), between two electrodes with an air gap between the surface of the PS and the upper electrode. Silica particles, 100 nm in diameter, were placed on the surface of the PS capillary bridges, and the sample was heated above the Tg of PS to enable particle motion. Samples were cooled to below Tg, and the locations of the particles were observed using scanning electron microscopy. The particles did not preferentially locate around the center of the capillary bridge, as predicted by others, but instead segregated to the edges. These results indicate that the forces driving particles to the three-phase contact line (air/PS/electrode surface) are greater than those locating particles around the center.
Collapse
Affiliation(s)
- Kathleen McEnnis
- †Polymer Science and Engineering Department, and ‡Physics Department, University of Massachusetts Amherst, Massachusetts 01003, United States
| | - Anthony D Dinsmore
- †Polymer Science and Engineering Department, and ‡Physics Department, University of Massachusetts Amherst, Massachusetts 01003, United States
| | - Thomas P Russell
- †Polymer Science and Engineering Department, and ‡Physics Department, University of Massachusetts Amherst, Massachusetts 01003, United States
| |
Collapse
|
35
|
Lee S, Kang HS, Ambrosio A, Park JK, Marrucci L. Directional Superficial Photofluidization for Deterministic Shaping of Complex 3D Architectures. ACS APPLIED MATERIALS & INTERFACES 2015; 7:8209-8217. [PMID: 25816857 DOI: 10.1021/acsami.5b01108] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The fabrication of micro- and nanostructures is one of the cornerstones of current materials science and technology. There is a strong interest in processing methods capable of manufacturing engineered complex structures on a large area. A method that is gaining a growing attention in this context is based on surface reshaping of photosensitive materials, such as certain azobenzene derivatives by way of a process of light-induced mass migration, also described as "athermal photofluidization". Here, we apply this method to prestructured substrate, converting simple periodic structures initially patterned only in two dimensions into complex-shaped three-dimensional (3D) structures by a single processing step over a large area. The optical variables of the irradiating beam are used to gain unprecedented deterministic control on the resulting 3D architectures. We also provide some initial demonstrations of the potential application of this novel shaping method, including unidirectional wetting surfaces and micro- and nanoscaled fluidic channel manufactured with it.
Collapse
Affiliation(s)
| | - Hong Suk Kang
- ‡Department of Chemical and Biomolecular Engineering and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Antonio Ambrosio
- §School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02115, United States
- ∥CNR-SPIN and Dipartimento di Scienze Fisiche, Universitàdegli Studi di Napoli Federico II, Via Cintia, Napoli 80126, Italy
| | - Jung-Ki Park
- ‡Department of Chemical and Biomolecular Engineering and Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | - Lorenzo Marrucci
- ∥CNR-SPIN and Dipartimento di Scienze Fisiche, Universitàdegli Studi di Napoli Federico II, Via Cintia, Napoli 80126, Italy
| |
Collapse
|
36
|
Nazaripoor H, Koch CR, Sadrzadeh M, Bhattacharjee S. Electrohydrodynamic patterning of ultra-thin ionic liquid films. SOFT MATTER 2015; 11:2193-2202. [PMID: 25639493 DOI: 10.1039/c4sm02477j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the electrohydrodynamic (EHD) patterning process, electrostatic destabilization of the air-polymer interface results in micro- and nano-size patterns in the form of raised formations called pillars. The polymer film in this process is typically assumed to behave like a perfect dielectric (PD) or leaky dielectric (LD). In this study, an electrostatic model is developed for the patterning of an ionic liquid (IL) polymer film. The IL model has a finite diffuse electric layer which overcomes the shortcoming of assuming infinitesimally large and small electric diffuse layers inherent in the PD and LD models respectively. The process of pattern formation is then numerically simulated by solving the weakly nonlinear thin film equation using finite difference with pseudo-staggered discretization and an adaptive time step. Initially, the pillar formation process in IL films is observed to be the same as that in PD films. Pillars initially form at random locations and their cross-section increases with time as the contact line expands on the top electrode. After the initial growth, for the same applied voltage and initial film thickness, the number of pillars on IL films is found to be significantly higher than that in PD films. The total number of pillars formed in 1 μm(2) area of the domain in an IL film is almost 5 times more than that in a similar PD film for the conditions simulated. In addition, the pillar structure size in IL films is observed to be more sensitive to initial film thickness compared to PD films.
Collapse
Affiliation(s)
- Hadi Nazaripoor
- Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G2G8.
| | | | | | | |
Collapse
|
37
|
Nazaripoor H, Koch CR, Bhattacharjee S. Electrical perturbations of ultrathin bilayers: role of ionic conductive layer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14734-14744. [PMID: 25419880 DOI: 10.1021/la503839x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The effect of electrostatic force on the dynamics, morphological evolution, and drainage time of ultrathin liquid bilayers (<100 nm) are investigated for perfect dielectric-perfect dielectric (PD-PD) and ionic liquid-perfect dielectric (IL-PD) bilayers. The weakly nonlinear "thin film" equation is solved numerically to obtain spatiotemporal evolution of the liquid-liquid interface responses to transverse electric field. In order to predict the electrostatic component of conjoining/disjoining pressure acting on the interface for IL-PD bilayers, an analytical model is developed using the nonlinear Poisson-Boltzmann equation. It is found that IL-PD bilayers with electric permittivity ratio of layers (lower to top), εr, greater than one remain stable under an applied electric field. An extensive numerical study is carried out to generate a map based on εr and the initial mean thickness of the lower layer. This map is used to predict the formation of various structures on PD-PD bilayer interface and provides a baseline for unstable IL-PD bilayers. The use of an ionic liquid (IL) layer is found to reduce the size of the structures, but results in polydispersed and disordered pillars spread over the domain. The numerical predictions follow similar trend of experimental observation of Lau and Russel. (Lau, C. Y.; Russel, W. B. Fundamental Limitations on Ordered Electrohydrodynamic Patterning; Macromolecules 2011, 44, 7746-7751).
Collapse
Affiliation(s)
- Hadi Nazaripoor
- Department of Mechanical Engineering, University of Alberta , Edmonton, Alberta T6G 2R3, Canada
| | | | | |
Collapse
|
38
|
Tian H, Wang C, Shao J, Ding Y, Li X. Electrohydrodynamic pressure enhanced by free space charge for electrically induced structure formation with high aspect ratio. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12654-12663. [PMID: 25268463 DOI: 10.1021/la5027043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Electrically induced structure formation (EISF) is an interesting and unique approach for generating a microstructured duplicate from a rheological polymer by a spatially modulated electric field induced by a patterned template. Most of the research on EISF have so far used various dielectric polymers (with an electrical conductivity smaller than 10(-10) S/m that can be considered a perfect dielectric), on which the electric field induces a Maxwell stress only due to the dipoles (or bounded charges) in the polymer molecules, leading to a structure with a small aspect ratio. This paper presents a different approach for improving the aspect ratio allowed in EISF by doping organic salt into the perfect dielectric polymer, i.e., turning the perfect dielectric into a leaky dielectric, considering the fact that the free space charges enriched in the leaky dielectric polymer can make an additional contribution to the Maxwell stress, i.e., electrohydrodynamic pressure, which is desirable for high aspect ratio structuring. Our numerical simulations and experimental tests have shown that a leaky dielectric polymer, with a small conductivity comparable to that of deionized water, can be much more effective at being electrohydrodynamically deformed into a high aspect ratio in comparison with a perfect dielectric polymer when both of them have roughly the same dielectric constant.
Collapse
Affiliation(s)
- Hongmiao Tian
- Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , Xi'an, Shaanxi 710049, China
| | | | | | | | | |
Collapse
|
39
|
Arshad TA, Kim CB, Prisco NA, Katzenstein JM, Janes DW, Bonnecaze RT, Ellison CJ. Precision Marangoni-driven patterning. SOFT MATTER 2014; 10:8043-50. [PMID: 25160514 DOI: 10.1039/c4sm01284d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A Marangoni flow is shown to occur when a polymer film possessing a spatially-defined surface energy pattern is heated above its glass transition to the liquid state. This can be harnessed to rapidly manufacture polymer films possessing prescribed height profiles. To quantify and verify this phenomenon, a model is described here which accurately predicts the formation, growth, and eventual dissipation of topographical features. The model predictions, based on numerical solutions of equations governing thin film dynamics with a Marangoni stress, are quantitatively compared to experimental measurements of thin polystyrene films containing photochemically patterned surface energy gradients. Good agreement between the model and the data is achieved at temperatures between 120 and 140 °C for a comprehensive range of heating times using reasonable physical properties as parameter inputs. For example, thickness variations that measure 102% of the starting film thickness are achieved in only 12 minutes of heating at 140 °C, values that are predicted by the model are within 6% and 3 min, respectively. The photochemical pattern that directed this flow possessed only a 0.2 dyne cm(-1) variation in surface tension between exposed and unexposed regions. The physical insights from the validated model suggest promising strategies to maximize the aspect ratio of the topographical features and minimize the processing time necessary to develop them.
Collapse
Affiliation(s)
- Talha A Arshad
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 East Dean Keeton Street, Austin, Texas 78712, USA.
| | | | | | | | | | | | | |
Collapse
|
40
|
Annepu H, Sarkar J. Miniaturized pattern formation in elastic films cast on sinusoidally patterned substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12278-12286. [PMID: 25238212 DOI: 10.1021/la502933c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The various morphologies that are formed when van der Waals forces or electric field is induced between film cast on a sinusoidal substrate and in contact proximity with a contactor or electrode are studied. Remarkably smaller length scales are achieved (λc < 2.96h) than those obtained with films cast on flat substrates. With van der Waals interactions, the patterns are uniformly formed throughout the film but are not regularly ordered. When electric field is used at critical voltage, more ordered, localized patterns are formed at the zones of large local interaction strengths. When these patterns are evolved by increasing the applied voltage, coexistence of all three phases-cavities, stripes, and columns-is observed throughout the film. The localized patterns that are initially formed vary with the voltage applied and strongly dictate the phases of evolution. A patterned substrate/patterned contactor assembly can be made to operate like its unpatterned counterpart by making the interaction strength same everywhere and yet yield uniform, regularly ordered, highly miniaturized patterns. Such patterns are very useful in various applications like microfluidics; they are formed with great ease and can be morphologically tuned by tuning the externally applied electric field.
Collapse
Affiliation(s)
- Hemalatha Annepu
- Chemical Engineering Department, Indian Institute of Technology Delhi , New Delhi 110 016, India
| | | |
Collapse
|
41
|
Yang Q, Li BQ, Ding Y, Shao J. Steady State of Electrohydrodynamic Patterning of Micro/Nanostructures on Thin Polymer Films. Ind Eng Chem Res 2014. [DOI: 10.1021/ie502288a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Qingzhen Yang
- State
Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, People’s Republic of China
| | - Ben Q. Li
- Department
of Mechanical Engineering, University of Michigan, Dearborn, Michigan 48128, United States
| | - Yucheng Ding
- State
Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, People’s Republic of China
| | - Jinyou Shao
- State
Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, People’s Republic of China
| |
Collapse
|
42
|
Karthik C, Manjuladevi V, Gupta R, Kumar S. Pattern formation in Langmuir–Blodgett films of tricycloquinazoline based discotic liquid crystal molecules. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
43
|
Formation of arbitrary patterns in ultraviolet cured polymer film via electrohydrodynamic patterning. ScientificWorldJournal 2014; 2014:840497. [PMID: 24723831 PMCID: PMC3956517 DOI: 10.1155/2014/840497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 01/09/2014] [Indexed: 11/17/2022] Open
Abstract
Electrohydrodynamic patterning of arbitrary patterns is achieved by optimizing the critical parameters (applied voltage and spacer height). The applied voltage has a great influence on the fidelity of L-shaped line structures with different sizes. The L-shaped line structures with high fidelity are obtained by using the moderate applied voltage. The spacer height has a great influence on the fidelity of square structures with different sizes. The square structures with high fidelity are obtained by using the low height spacer. The multi-field coupling transient finite element simulation demonstrates that the lack of polymer owing to the high height spacer leads to the formation of defects.
Collapse
|
44
|
Dey M, Bandyopadhyay D, Sharma A, Qian S, Joo SW. Charge Leakage Mediated Pattern Miniaturization in the Electric Field Induced Instabilities of an Elastic Membrane. Ind Eng Chem Res 2014. [DOI: 10.1021/ie500378k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohar Dey
- School
of Mechanical Engineering, Yeungnam University, Gyeongsan 712749, South Korea
| | - Dipankar Bandyopadhyay
- Department
of Chemical Engineering, Indian Institute of Technology Guwahati, 781039, Assam, India
- Centre
for Nanotechnology, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Ashutosh Sharma
- Department
of Chemical Engineering, Indian Institute of Technology Kanpur, UP 208016, India
| | - Shizhi Qian
- Department
of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, Virginia 23529, United States
| | - Sang Woo Joo
- School
of Mechanical Engineering, Yeungnam University, Gyeongsan 712749, South Korea
| |
Collapse
|
45
|
Tian H, Shao J, Ding Y, Li X, Hu H. Electrohydrodynamic Micro-/Nanostructuring Processes Based on Prepatterned Polymer and Prepatterned Template. Macromolecules 2014. [DOI: 10.1021/ma402456u] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hongmiao Tian
- Micro- and Nano-manufacturing Research
Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Jinyou Shao
- Micro- and Nano-manufacturing Research
Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Yucheng Ding
- Micro- and Nano-manufacturing Research
Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Xiangming Li
- Micro- and Nano-manufacturing Research
Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Hong Hu
- Micro- and Nano-manufacturing Research
Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| |
Collapse
|
46
|
Li H, Yu W, Wang Y, Bu H, Liu Z, Abraham E, Desmulliez MPY. Simulation of the electrohydrodynamic instability process used in the fabrication of hierarchic and hollow micro/nanostructures. RSC Adv 2014. [DOI: 10.1039/c3ra48046a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
47
|
Li H, Yu W, Wang T, Zhang H, Niu W, Abraham E, Desmulliez MPY. Fabrication of micro-optical elements on curved substrates by electrostatic induced lithography. RSC Adv 2014. [DOI: 10.1039/c4ra05823b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This article reports the fabrication and characterization of polymeric micro-optical elements on curved substrates using electrostatic induced lithography.
Collapse
Affiliation(s)
- H. Li
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun, P.R.China
| | - W. Yu
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun, P.R.China
| | - T. Wang
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun, P.R.China
| | - H. Zhang
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun, P.R.China
| | - W. Niu
- State Key Laboratory of Applied Optics
- Changchun Institute of Optics
- Fine Mechanics & Physics
- Chinese Academy of Sciences
- Changchun, P.R.China
| | - E. Abraham
- MIcroSystems Engineering Centre (MISEC)
- School of Engineering & Physical Sciences
- Heriot-Watt University
- Edinburgh EH14 4AS, UK
| | - M. P. Y. Desmulliez
- MIcroSystems Engineering Centre (MISEC)
- School of Engineering & Physical Sciences
- Heriot-Watt University
- Edinburgh EH14 4AS, UK
| |
Collapse
|
48
|
|
49
|
Tian H, Shao J, Ding Y, Li X, Liu H. Numerical characterization of electrohydrodynamic micro- or nanopatterning processes based on a phase-field formulation of liquid dielectrophoresis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4703-4714. [PMID: 23506225 DOI: 10.1021/la400535p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The electrohydrodynamic patterning of polymer is a unique technique for micro- and nanostructuring where an electric voltage is applied to an electrode pair consisting of a patterned template and a polymer-coated substrate either in contact or separated by an air gap to actuate the deformation of the rheological polymer. Depending on the template composition, three processes were proposed for implementing the EHDP technique and have received a great amount of attention (i.e., electrostatic force-assisted nanoimprint, dielectrophoresis-electrocapillary force-driven imprint, and electrically induced structure formation). A numerical approach, which is versatile for visualizing the full evolution of micro- or nanostructures in these patterning processes or their variants, is a desirable critical tool for optimizing the process variables in industrial applications of this structuring technique. Considering the fact that all of these processes use a dielectric and viscous polymer (behaving mechanically as a liquid) and are carried out in ambient air, this Article presents a generalized formulation for the numerical characterization of the EHDP processes by coupling liquid dielectrophoresis (L-DEP) and the phase field of the air-liquid dual phase. More importantly, some major scale effects, such as the surface tension, contact angle, liquid-solid interface slip, and non-Newtonian viscosity law are introduced, which can impact the accuracy of the numerical results, as shown experimentally by our electrical actuation of a dielectric microdroplet as a test problem. The numerical results are in good agreement with or are well explained by experimental observations published for the three EHDP processes.
Collapse
Affiliation(s)
- Hongmiao Tian
- Micro- and Nano-manufacturing Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
| | | | | | | | | |
Collapse
|
50
|
Janes DW, Katzenstein JM, Shanmuganathan K, Ellison CJ. Directing convection to pattern thin polymer films. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/polb.23262] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|