23 results on '"Arun K Kota"'
Search Results
2. On-demand, remote and lossless manipulation of biofluid droplets
- Author
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Wei Wang, Jiefeng Sun, Sravanthi Vallabhuneni, Benjamin Pawlowski, Hamed Vahabi, Kimberly Nellenbach, Ashley C. Brown, Frank Scholle, Jianguo Zhao, and Arun K. Kota
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Mechanics of Materials ,Process Chemistry and Technology ,Point-of-Care Systems ,Health Personnel ,Humans ,General Materials Science ,Electrical and Electronic Engineering ,Saliva ,Pandemics ,Disease Outbreaks - Abstract
To minimize exposure of healthcare workers and clinical laboratory personnel to infectious liquids, we designed biofluid manipulators for on-demand handling of liquid droplets, in-plane or out-of-plane, in a remote and lossless manner.
- Published
- 2023
3. Designing non-textured, all-solid, slippery hydrophilic surfaces
- Author
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Hamed, Vahabi, Sravanthi, Vallabhuneni, Mohammadhasan, Hedayati, Wei, Wang, Diego, Krapf, Matt J, Kipper, Nenad, Miljkovic, and Arun K, Kota
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General Materials Science - Abstract
Slippery surfaces are sought after due to their wide range of applications in self-cleaning, drag reduction, fouling-resistance, enhanced condensation, biomedical implants etc. Recently, non-textured, all-solid, slippery surfaces have gained significant attention because of their advantages over super-repellent surfaces and lubricant-infused surfaces. Currently, almost all non-textured, all-solid, slippery surfaces are hydrophobic. In this work, we elucidate the systematic design of non-textured, all-solid, slippery hydrophilic (SLIC) surfaces by covalently grafting polyethylene glycol (PEG) brushes to smooth substrates. Furthermore, we postulate a plateau in slipperiness above a critical grafting density, which occurs when the tethered brush size is equal to the inter-tether distance. Our SLIC surfaces demonstrate exceptional performance in condensation and fouling-resistance compared to non-slippery hydrophilic surfaces and slippery hydrophobic surfaces. Based on these results, SLIC surfaces constitute an emerging class of surfaces with the potential to benefit multiple technological landscapes ranging from thermofluidics to biofluidics.
- Published
- 2022
4. Continuous Liquid–Liquid Extraction and in-Situ Membrane Separation of Miscible Liquid Mixtures
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Joseph M. Mabry, Anish Tuteja, Gibum Kwon, Andrew J. Guenthner, Arun K. Kota, Josiah T. Reams, Ethan Post, Kevin R Lamison, Chao Li, and David L. Speer
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Materials science ,Extraction (chemistry) ,Surfaces and Interfaces ,Condensed Matter Physics ,Unit operation ,Supercritical fluid ,law.invention ,Membrane technology ,Membrane ,Chemical engineering ,law ,Liquid–liquid extraction ,Mass transfer ,Electrochemistry ,General Materials Science ,Distillation ,Spectroscopy - Abstract
Separation operations are critical across a wide variety of manufacturing industries and account for about one-quarter of all in-plant energy consumption in the United States. Conventional liquid-liquid separation operations require either thermal or chemical treatment, both of which have a large environmental impact and carbon footprint. Consequently, there is a great need to develop sustainable, clean methodologies for separation of miscible liquid mixtures. The greatest opportunities to achieve this lie in replacing high-energy separation operations (e.g., distillation) with low-energy alternatives such as liquid-liquid extraction. One of the primary design challenges in liquid-liquid extraction is to maximize the interfacial area between two immiscible (e.g., polar and nonpolar) liquids for efficient mass transfer. However, this often involves energy-intensive methods including ultrasonication, pumping the feed and the extractant through packed columns with high tortuosity, or using a supercritical fluid as an extractant. Emulsifying the feed and the extractant, especially with a surfactant, offers a large interfacial area, but subsequent separation of emulsions can be energy-intensive and expensive. Thus, emulsions are typically avoided in conventional extraction operations. Herein, we discuss a novel, easily scalable, platform separation methodology termed CLEANS (continuous liquid-liquid extraction and in-situ membrane separation). CLEANS integrates emulsion-enhanced extraction with continuous, gravity-driven, membrane-based separation of emulsions into a single unit operation. Our results demonstrate that the addition of a surfactant and emulsification significantly enhance extraction (by >250% in certain cases), even for systems where the best extractants for miscible liquid mixtures are known. Utilizing the CLEANS methodology, we demonstrate continuous separation of a wide range of miscible liquid mixtures, including soluble organic molecules from oils, alcohols from esters, and even azeotropes.
- Published
- 2021
5. Droplet Evaporation Dynamics of Low Surface Tension Fluids Using the Steady Method
- Author
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Arun K. Kota, Marisa Gnadt, Hamed Vahabi, Ahmet Alperen Gunay, Soumyadip Sett, and Nenad Miljkovic
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Work (thermodynamics) ,Materials science ,Marangoni effect ,Dodecane ,Evaporation ,Analytical chemistry ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Contact angle ,Surface tension ,chemistry.chemical_compound ,chemistry ,Electrochemistry ,General Materials Science ,Relative humidity ,Wetting ,0210 nano-technology ,Spectroscopy - Abstract
Droplet evaporation governs many heat- and mass-transfer processes germane in nature and industry. In the past 3 centuries, transient techniques have been developed to characterize the evaporation of sessile droplets. These methods have difficulty in reconciling transient effects induced by the droplet shape and size changes during evaporation. Furthermore, investigation of evaporation of microdroplets residing on wetting substrates, or fluids having low surface tensions (
- Published
- 2020
6. Hemocompatibility of Super-Repellent surfaces: Current and Future
- Author
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Ketul C. Popat, Sanli Movafaghi, Wei Wang, Lakshmi Prasad Dasi, David Bark, and Arun K. Kota
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animal structures ,business.industry ,Process Chemistry and Technology ,Platelet adhesion ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,0104 chemical sciences ,3. Good health ,Mechanics of Materials ,Medicine ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Biomedical engineering - Abstract
Virtually all blood-contacting medical implants and devices initiate immunological events in the form of thrombosis and inflammation. Typically, patients receiving such implants are also given large doses of anticoagulants, which pose a high risk and a high cost to the patient. Thus, the design and development of surfaces with improved hemocompatibility and reduced dependence on anticoagulation treatments is paramount for the success of blood-contacting medical implants and devices. In the past decade, the hemocompatibility of super-repellent surfaces (i.e., surfaces that are extremely repellent to liquids) has been extensively investigated because such surfaces greatly reduce the blood-material contact area, which in turn reduces the area available for protein adsorption and blood cell or platelet adhesion, thereby offering the potential for improved hemocompatibility. In this review, we critically examine the progress made in characterizing the hemocompatibility of super-repellent surfaces, identify the unresolved challenges and highlight the opportunities for future research on developing medical implants and devices with super-repellent surfaces.
- Published
- 2020
7. Fabrication of Nanostructured Omniphobic and Superomniphobic Surfaces with Inexpensive CO2 Laser Engraver
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Soran Shadman, Azer P. Yalin, Arun K. Kota, Wei Wang, Sanli Movafaghi, and Anudeep Pendurthi
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Fabrication ,Materials science ,Laser ablation ,Nanostructure ,Microfluidics ,Nanotechnology ,02 engineering and technology ,Surface finish ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,0104 chemical sciences ,law.invention ,Surface tension ,law ,General Materials Science ,Wetting ,0210 nano-technology - Abstract
Superomniphobic surfaces (i.e., surfaces that are extremely repellent to both high surface tension liquids like water and low surface tension liquid like oils) can be fabricated through a combination of surface chemistry that imparts low solid surface energy with a re-entrant surface texture. Recently, surface texturing with lasers has received significant attention because laser texturing is scalable, solvent-free, and can produce a monolithic texture on virtually any material. In this work, we fabricated nanostructured omniphobic and superomniphobic surfaces with a variety of materials using a simple, inexpensive and commercially available CO2 laser engraver. Further, we demonstrated that the nanostructured omniphobic and superomniphobic surfaces fabricated using our laser texturing technique can be used to design patterned surfaces, surfaces with discrete domains of the desired wettability, and on-surface microfluidic devices.
- Published
- 2017
8. Interaction of blood plasma proteins with superhemophobic titania nanotube surfaces
- Author
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Kirsten Kauk, Arun K. Kota, Sanli Movafaghi, Ketul C. Popat, and Roberta M. Sabino
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Biocompatibility ,Surface Properties ,Biomedical Engineering ,Pharmaceutical Science ,Medicine (miscellaneous) ,Bioengineering ,Biocompatible Materials ,Enzyme-Linked Immunosorbent Assay ,02 engineering and technology ,Fibrinogen ,Article ,03 medical and health sciences ,Thrombin ,Platelet Adhesiveness ,medicine ,Humans ,General Materials Science ,Blood Coagulation ,030304 developmental biology ,Whole blood ,Titanium ,0303 health sciences ,Factor XII ,Nanotubes ,Chemistry ,Factor XII activation ,Blood Proteins ,021001 nanoscience & nanotechnology ,Blood proteins ,Kinetics ,Biophysics ,Molecular Medicine ,Adsorption ,0210 nano-technology ,medicine.drug ,Protein adsorption - Abstract
The need to improve blood biocompatibility of medical devices is urgent. As soon as blood encounters a biomaterial implant, proteins adsorb on its surfaces, often leading to several complications such as thrombosis and failure of the device. Therefore, controlling protein adsorption plays a major role in developing hemocompatible materials. In this study, the interaction of key blood plasma proteins with superhemophobic titania nanotube substrates and the blood clotting responses was investigated. The substrate stability was evaluated and fibrinogen adsorption and thrombin formation from plasma were assessed using ELISA. Whole blood clotting kinetics was also investigated, and Factor XII activation on the substrates was characterized by an in vitro plasma coagulation time assay. The results show that superhemophobic titania nanotubes are stable and considerably decrease surface protein adsorption/Factor XII activation as well as delay the whole blood clotting, and thus can be a promising approach for designing blood contacting medical devices.
- Published
- 2019
9. Droplet Jumping: Effects of Droplet Size, Surface Structure, Pinning, and Liquid Properties
- Author
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Arun K. Kota, Xiao Yan, Soumyadip Sett, Lezhou Feng, Feng Chen, Chongyan Zhao, Nenad Miljkovic, Hamed Vahabi, Zhiyong Huang, and Leicheng Zhang
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Length scale ,Work (thermodynamics) ,Materials science ,Scattering ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,Radius ,Mechanics ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Rotation ,medicine.disease_cause ,01 natural sciences ,0104 chemical sciences ,Physics::Fluid Dynamics ,Jumping ,Physics::Atomic and Molecular Clusters ,medicine ,General Materials Science ,0210 nano-technology ,Scaling ,Phase diagram - Abstract
Coalescence-induced droplet jumping has the potential to enhance the efficiency of a plethora of applications. Although binary droplet jumping is quantitatively understood from energy and hydrodynamic perspectives, multiple aspects that affect jumping behavior, including droplet size mismatch, droplet-surface interaction, and condensate thermophysical properties, remain poorly understood. Here, we develop a visualization technique utilizing microdroplet dispensing to study droplet jumping dynamics on nanostructured superhydrophobic, hierarchical superhydrophobic, and hierarchical biphilic surfaces. We show that on the nanostructured superhydrophobic surface the jumping velocity follows inertial-capillary scaling with a dimensionless velocity of 0.26 and a jumping direction perpendicular to the substrate. A droplet mismatch phase diagram was developed showing that jumping is possible for droplet size mismatch up to 70%. On the hierarchical superhydrophobic surface, jumping behavior was dependent on the ratio between the droplet radius Ri and surface structure length scale L. For small droplets ( Ri ≤ 5 L), the jumping velocity was highly scattered, with a deviation of the jumping direction from the substrate normal as high as 80°. Surface structure length scale effects were shown to vanish for large droplets ( Ri > 5 L). On the hierarchical biphilic surface, similar but more significant scattering of the jumping velocity and direction was observed. Droplet-size-dependent surface adhesion and pinning-mediated droplet rotation were responsible for the reduced jumping velocity and scattered jumping direction. Furthermore, droplet jumping studies of liquids with surface tensions as low as 38 mN/m were performed, further confirming the validity of inertial-capillary scaling for varying condensate fluids. Our work not only demonstrates a powerful platform to study droplet-droplet and droplet-surface interactions but provides insights into the role of fluid-substrate coupling as well as condensate properties during droplet jumping.
- Published
- 2019
10. Free-Standing, Flexible, Superomniphobic Films
- Author
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Sanli Movafaghi, Arun K. Kota, Wei Wang, and Hamed Vahabi
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Materials science ,Fabrication ,Solid surface ,General Materials Science ,Nanotechnology ,02 engineering and technology ,Texture (crystalline) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,0104 chemical sciences ,Process conditions - Abstract
Fabrication of most superomniphobic surfaces requires complex process conditions or specialized and expensive equipment or skilled personnel. In order to circumvent these issues and make them end-user-friendly, we developed the free-standing, flexible, superomniphobic films. These films can be stored and delivered to the end-users, who can readily attach them to virtually any surface (even irregular shapes) and impart superomniphobicity. The hierarchical structure, the re-entrant texture, and the low solid surface energy render our films superomniphobic for a wide variety of liquids. We demonstrate that our free-standing, flexible, superomniphobic films have applications in enhanced chemical resistance and enhanced weight bearing.
- Published
- 2016
11. Durable gels with ultra-low adhesion to ice
- Author
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Arun K. Kota, Darryl L. Beemer, and Wei Wang
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Materials science ,Renewable Energy, Sustainability and the Environment ,technology, industry, and agriculture ,Nanotechnology ,macromolecular substances ,02 engineering and technology ,General Chemistry ,Adhesion ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Durability ,0104 chemical sciences ,Ice adhesion ,General Materials Science ,Composite material ,0210 nano-technology - Abstract
In this work, building on the principles of adhesion mechanics, we developed novel inexpensive, environmentally benign, non-corrosive PDMS gels that offer ultra-low adhesion to ice as well as outstanding mechanical durability. We elucidated the mechanism of separation of ice from our PDMS gels via separation pulses. We envision that our durable PDMS gels with ultra-low ice adhesion strength as well as the improved understanding of the separation mechanism will enable universal deicing design strategies in aviation, maritime, power, automotive, and energy sectors.
- Published
- 2016
12. Wettability Engendered Templated Self-assembly (WETS) for Fabricating Multiphasic Particles
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Philip Wong, Arun K. Kota, Sai P. R. Kobaku, Duck Hyun Lee, Raghuraman G. Karunakaran, Gibum Kwon, and Anish Tuteja
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chemistry.chemical_classification ,Fabrication ,Template ,Materials science ,chemistry ,Dispersity ,Particle ,Nanoparticle ,General Materials Science ,Nanotechnology ,Polymer ,Self-assembly ,Layer (electronics) - Abstract
Precise control over the geometry and chemistry of multiphasic particles is of significant importance for a wide range of applications. In this work, we have developed one of the simplest methodologies for fabricating monodisperse, multiphasic micro- and nanoparticles possessing almost any composition, projected shape, modulus, and dimensions as small as 25 nm. The synthesis methodology involves the fabrication of a nonwettable surface patterned with monodisperse, wettable domains of different sizes and shapes. When such patterned templates are dip-coated with polymer solutions or particle dispersions, the liquids, and consequently the polymer or the particles, preferentially self-assemble within the wettable domains. Utilizing this phenomenon, we fabricate multiphasic assemblies with precisely controlled geometry and composition through multiple, layered depositions of polymers and/or particles within the patterned domains. Upon releasing these multiphasic assemblies from the template using a sacrificial layer, we obtain multiphasic particles. The templates can then be readily reused (over 20 times in our experiments) for fabricating a new batch of particles, enabling a rapid, inexpensive, and easily reproducible method for large-scale manufacturing of multiphasic particles.
- Published
- 2015
13. Coalescence-Induced Self-Propulsion of Droplets on Superomniphobic Surfaces
- Author
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Arun K. Kota, Wei Wang, Hamed Vahabi, Seth Davies, and Joseph M. Mabry
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Coalescence (physics) ,Work (thermodynamics) ,Range (particle radiation) ,Materials science ,Thermodynamics ,02 engineering and technology ,Radius ,010402 general chemistry ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,01 natural sciences ,Ohnesorge number ,0104 chemical sciences ,Condensed Matter::Soft Condensed Matter ,Physics::Fluid Dynamics ,Viscosity ,Jumping ,Self propulsion ,medicine ,General Materials Science ,0210 nano-technology - Abstract
We utilized superomniphobic surfaces to systematically investigate the different regimes of coalescence-induced self-propulsion of liquid droplets with a wide range of droplet radii, viscosities, and surface tensions. Our results indicate that the nondimensional jumping velocity Vj* is nearly constant (Vj* ≈ 0.2) in the inertial-capillary regime and decreases in the visco-capillary regime as the Ohnesorge number Oh increases, in agreement with prior work. Within the visco-capillary regime, decreasing the droplet radius R0 results in a more rapid decrease in the nondimensional jumping velocity Vj* compared to increasing the viscosity μ. This is because decreasing the droplet radius R0 increases the inertial-capillary velocity Vic in addition to increasing the Ohnesorge number Oh.
- Published
- 2017
14. Amphiphilic Colloidal Surfactants Based on Electrohydrodynamic Co-jetting
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Jaewon Yoon, Joerg Lahann, Srijanani Bhaskar, Anish Tuteja, and Arun K. Kota
- Subjects
chemistry.chemical_classification ,Vinyl alcohol ,Materials science ,Infrared spectroscopy ,Janus particles ,Nanotechnology ,Polymer ,Silsesquioxane ,chemistry.chemical_compound ,Colloid ,chemistry ,Amphiphile ,General Materials Science ,Electrohydrodynamics - Abstract
A novel synthetic route for the preparation of amphiphilic Janus particles based on electrohydrodynamic cojetting has been developed. In this approach, selective encapsulation of hydrophobic fluorodecyl-polyhedral oligomeric silsesquioxane (F-POSS) in one compartment and a poly(vinyl alcohol) in the second compartment results in colloidal particles with surfactant-like properties including the self-organization at oil-water and air-water interfaces. Successful localization of the respective polymers in different compartments of the same particle is confirmed by a combination of fluorescence microscopy, vibrational spectroscopy, and ζ-potential measurements. We believe that this straightforward synthetic approach may lead to a diverse class of surface-active colloids that will have significant relevance ranging from basic scientific studies to immediate applications in areas, such as pharmaceutical sciences or cosmetics.
- Published
- 2013
15. Superomniphobic surfaces: Design and durability
- Author
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Anish Tuteja, Arun K. Kota, and Wonjae Choi
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Nanostructure ,Materials science ,Nanotechnology ,Surface finish ,engineering.material ,Condensed Matter Physics ,Durability ,Surface energy ,Contact angle ,Surface tension ,Coating ,Energy materials ,engineering ,General Materials Science ,Physical and Theoretical Chemistry ,Composite material - Abstract
Surfaces that display liquid contact angles greater than 150° along with low contact angle hysteresis for liquids with both high and low surface tension values are known as superomniphobic surfaces. Such surfaces are of interest for a diverse array of applications, including self-cleaning surfaces, nonfouling surfaces, stain-free clothing, spill-resistant protective wear, drag reduction, and fingerprint-resistant surfaces. Recently, significant advances have been made in understanding the criteria required to design superomniphobic surfaces. In this article, we discuss the roles of surface energy, roughness, re-entrant texture, and hierarchical structure in fabricating superomniphobic surfaces. We also provide a review of different superomniphobic surfaces reported recently in the literature and emphasize the need for mechanical, chemical, and radiation durability of superomniphobic surfaces for practical applications. Finally, we conclude with a discussion of the unresolved challenges in developing durable superomniphobic surfaces that define the scope for further improvements in the field.
- Published
- 2013
16. Superhydrophobic Coatings with Edible Materials
- Author
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Sanli Movafaghi, Salman R. Khetani, Matthew D. Davidson, Karsten Lockwood, Lewis M. Boyd, Hamed Vahabi, Wei Wang, and Arun K. Kota
- Subjects
Wax ,Materials science ,Surface Properties ,Food Packaging ,Nanotechnology ,Single step ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Contact angle ,Coating ,Food ,visual_art ,visual_art.visual_art_medium ,engineering ,General Materials Science ,0210 nano-technology - Abstract
We used FDA-approved, edible materials to fabricate superhydrophobic coatings in a simple, low cost, scalable, single step process. Our coatings display high contact angles and low roll off angles for a variety of liquid products consumed daily and facilitate easy removal of liquids from food containers with virtually no residue. Even at high concentrations, our coatings are nontoxic, as shown using toxicity tests.
- Published
- 2016
17. Hierarchically Structured Superoleophobic Surfaces with Ultralow Contact Angle Hysteresis
- Author
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Arun K. Kota, Anish Tuteja, Yongxin Li, and Joseph M. Mabry
- Subjects
Materials science ,Surface Properties ,Mechanical Engineering ,Nanotechnology ,Models, Theoretical ,Microspheres ,Heptanes ,Microsphere ,Physics::Fluid Dynamics ,Contact angle ,Hysteresis ,Tilt (optics) ,Mechanics of Materials ,Microscopy ,Microscopy, Electron, Scanning ,General Materials Science ,Physics::Chemical Physics ,Composite material ,Oils - Abstract
Hierarchically structured, superoleophobic surfaces are demonstrated that display one of the lowest contact angle hysteresis values ever reported - even with extremely low-surface-tension liquids such as n-heptane. Consequently, these surfaces allow, for the first time, even ≈2 μL n-heptane droplets to bounce and roll-off at tilt angles. ≤ 2°.
- Published
- 2012
18. Nanomechanical characterization of dispersion and its effects in nano-enhanced polymers and polymer composites
- Author
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Hugh A. Bruck, Alan L. Gershon, Arun K. Kota, and Daniel P. Cole
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chemistry.chemical_classification ,Materials science ,Carbon nanofiber ,Mechanical Engineering ,Sonication ,Thermosetting polymer ,Epoxy ,Polymer ,Avrami equation ,chemistry ,Mechanics of Materials ,visual_art ,Nanofiber ,visual_art.visual_art_medium ,General Materials Science ,Composite material ,Dispersion (chemistry) - Abstract
In this paper, a new approach for characterizing dispersion in nano-enhanced polymers and polymer composites using nanomechanical characterization is developed. Dispersion of Carbon nanofibers (CNFs) as a model nanoscale ingredient is characterized in two model polymer systems: (a) a thermoplastic polymer processed using a Twin Screw Extruder, and (b) a thermoset epoxy processed using sonication during solvent processing. For the first time, the modulus of agglomerated nanofibers was isolated from the polymer matrix enhanced with dispersed nanofibers by using nanomechanical characterization. Thus, it was possible to use these nanomechanical properties in a microstructural model using a Rule-of-Mixtures (ROM) formulation to determine the fraction of dispersed nanofibers, which yielded a dispersion limit of 3 vol% CNFs in the nano-enhanced thermoplastic polymer and 3.5 vol% CNFs in the nano-enhanced thermoset epoxy. It was also possible to predict the modulus measured using microtensile testing, and to determine an effective modulus of 30 GPa for the CNFs, which was attributed to a spring-like effect from kinking along the nanofibers. Applying this characterization to control of dispersion through sonication in the nano-enhanced thermoset epoxy, it was possible to determine the degree of dispersion with sonication time which was described using an Avrami equation. Finally, a carbon-fiber mat was used to create a model nano-enhanced polymer composite whose properties were found to be insensitive to sonication time due to filtering effects from the carbon-fiber mat and varied with CNF concentration in a manner where the CNF modulus could be extrapolated to 30 GPa, consistent with the nano-enhanced polymers.
- Published
- 2010
19. Metamorphic Superomniphobic Surfaces
- Author
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Walter Voit, Arun K. Kota, Alexandra Joshi-Imre, Wei Wang, Joshua Salazar, and Hamed Vahabi
- Subjects
Materials science ,Morphology (linguistics) ,Mechanical Engineering ,Metamorphic rock ,Nanotechnology ,02 engineering and technology ,Shape-memory alloy ,Surface finish ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Shape-memory polymer ,Wetting transition ,Mechanics of Materials ,Drug release ,General Materials Science ,Wetting ,0210 nano-technology - Abstract
Superomniphobic surfaces are extremely repellent to virtually all liquids. By combining superomniphobicity and shape memory effect, metamorphic superomniphobic (MorphS) surfaces that transform their morphology in response to heat are developed. Utilizing the MorphS surfaces, the distinctly different wetting transitions of liquids with different surface tensions are demonstrated and the underlying physics is elucidated. Both ex situ and in situ wetting transitions on the MorphS surfaces are solely due to transformations in morphology of the surface texture. It is envisioned that the robust MorphS surfaces with reversible wetting transition will have a wide range of applications including rewritable liquid patterns, controlled drug release systems, lab-on-a-chip devices, and biosensors.
- Published
- 2017
20. On-demand separation of oil-water mixtures
- Author
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Arun K. Kota, Anish Tuteja, Joseph M. Mabry, Ameya Sohani, Yongxin Li, and Gibum Kwon
- Subjects
Work (thermodynamics) ,Gravity (chemistry) ,Chromatography ,Materials science ,Mechanical Engineering ,Separation (aeronautics) ,Water ,Unit operation ,Membrane ,Chemical engineering ,Mechanics of Materials ,On demand ,Alkanes ,Electrowetting ,General Materials Science ,Oil water ,Emulsions ,Dimethylpolysiloxanes ,Oils - Abstract
In this work, the first-ever membrane-based single unit operation that enables gravity driven, on-demand separation of various oil-water mixtures is developed. Using this methodology, the on-demand separation of free oil and water, oil-in-water emulsions, and water-in-oil emulsions is demonstrated, with ≥99.9% separation efficiency. A scaled-up apparatus to separate larger quantities (several liters) of oil-water emulsions is also developed.
- Published
- 2012
21. High-efficiency, ultrafast separation of emulsified oil–water mixtures
- Author
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Anish Tuteja and Arun K. Kota
- Subjects
Chromatography ,Materials science ,Emulsified oil ,Separation (aeronautics) ,Carbon nanotube ,Orders of magnitude (numbers) ,Condensed Matter Physics ,Chinese academy of sciences ,law.invention ,Membrane ,Chemical engineering ,law ,Modeling and Simulation ,Oil spill ,General Materials Science ,Ultrashort pulse - Abstract
Multiple oil spill disasters over the last few years have highlighted the challenges of effective oil–water separation. The separation of oil–water micro- and nano-emulsions (emulsions with dispersed droplet sizes in the micro- or nano-meter range) can be particularly difficult.1, 2 Shi et al.3 from the Chinese Academy of Sciences in Suzhou and Beijing have now developed ultrathin carbon nanotube membranes that can separate a wide range of oil–water micro- and nano-emulsions with separation efficiency >99.9%. Perhaps more significantly, the separation fluxes are 2–3 orders of magnitude higher than those obtained with current commercially available separation membranes.
- Published
- 2013
22. Superoleophobic Surfaces: Hierarchically Structured Superoleophobic Surfaces with Ultralow Contact Angle Hysteresis (Adv. Mater. 43/2012)
- Author
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Yongxin Li, Arun K. Kota, Anish Tuteja, and Joseph M. Mabry
- Subjects
Contact angle ,Hysteresis ,Materials science ,Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,Nanotechnology - Published
- 2012
23. Quantitative characterization of the formation of an interpenetrating phase composite in polystyrene from the percolation of multiwalled carbon nanotubes
- Author
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Hugh A. Bruck, Dan Powell, Bani H. Cipriano, Arun K. Kota, and Srinivasa R. Raghavan
- Subjects
chemistry.chemical_classification ,Materials science ,Polymer nanocomposite ,Mechanical Engineering ,Composite number ,Bioengineering ,Percolation threshold ,General Chemistry ,Polymer ,Dynamic mechanical analysis ,Condensed Matter::Soft Condensed Matter ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Percolation ,Phase (matter) ,General Materials Science ,Polystyrene ,Electrical and Electronic Engineering ,Composite material - Abstract
For the first time, an interpenetrating phase polymer nanocomposite formed by the percolation of multiwalled carbon nanotubes (MWCNTs) in polystyrene (PS) has been quantitatively characterized through electrical conductivity measurements and melt rheology. Both sets of measurements, in conjunction with scanning electron microscopy (SEM) images, indicate the presence of a continuous phase of percolated MWCNTs appearing at particle concentrations exceeding 2 vol% MWCNTs in PS. To quantify the amount of this continuous phase present in the PS/MWCNT composite, electrical conductivity data at various MWCNT concentrations, β, are correlated with a proposed degree of percolation, , developed using a conventional power-law formula with and without a percolation threshold. To quantify the properties of the interpenetrating phase polymer nanocomposite, the PS/MWCNT composite is treated as a combination of two phases: a continuous phase consisting of a pseudo-solid-like network of percolated MWCNTs, and a continuous PS phase reinforced by non-interacting MWCNTs. The proposed degree of percolation is used to quantify the distribution of MWCNTs among the phases, and is then used in a rule-of-mixtures formulation for the storage modulus, , and the loss modulus, , to quantify the properties of the continuous phase consisting of percolated MWCNTs and the continuous PS phase reinforced by non-interacting MWCNTs from the experimental melt rheology data. The properties of the continuous phase of percolated MWCNTs are indicative of a scaffold-like microstructure exhibiting an elastic behavior with a complex modulus of 360 kPa at lower frequencies and viscoplastic behavior with a complex viscosity of 6 kPa s rad−1 at higher frequencies, most likely due to a stick–slip friction mechanism at the interface of the percolated MWCNTs. Additional evidence of this microstructure was obtained via scanning electron microscopy. This research has important implications in providing a new methodology based on the electrical and rheological properties of the polymer nanocomposite for quantifying the continuous phase formed by the percolation of new functionalized nanostructures being developed for: (a) controlling the percolation of the nanostructures through self-assembly, (b) enhancing their interaction with the continuous reinforced polymer phase, (c) enhancing the cohesion between nanostructures.
- Published
- 2007
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