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Lohani D, Sarkar S. Interconnected drying phenomena in nanoparticle laden water-ethanol binary droplets. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:35. [PMID: 33742250 DOI: 10.1140/epje/s10189-021-00045-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Understanding the evaporation of a multi-component droplet has found immense importance in various technological applications. This study investigates the evaporation behaviour of a colloidal binary droplet system comprising of the ethanol-water mixture and polystyrene nanoparticles. The wetting and evaporation dynamics were studied with an emphasis on the collective influence of ethanol and nanoparticle concentrations. The temporal behaviour of the contact angles, shapes and volumes of the droplets was monitored in order to analyse the evaporative behaviour. With increase of ethanol concentrations, the binary droplet volumes were found to decrease nonlinearly with time. Ethanol being more volatile evaporated in the initial stage. Towards the end of the evaporation process, the evaporation characteristics mimics the behaviour of pure water. Our study shows that the initial contact angle decreases monotonically with increased concentration of ethanol in the mixture. The contact angle is maximum for a particular nanoparticle concentration. Droplets with higher ethanol concentration show higher wettability which in its turn is maximum for low nanoparticle concentrations. This trend shows the interconnected effect of ethanol and nanoparticle concentrations on evaporation. Rim width of the final deposition pattern increases with nanoparticle concentration although it is almost independent of ethanol concentration. Finally, it is noticed that fast evaporation of a relatively more volatile component in a binary mixture droplet leads to nanoparticle segregation for low nanoparticle concentrations. Thus for binary mixtures, the evaporation of the more volatile component, ethanol for our case, offers characteristic differences in the resulting evaporation dynamics from that of pure water which finds applicability for multi-component evaporation processes.
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Affiliation(s)
- Deepa Lohani
- Department of Physics, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India
| | - Subhendu Sarkar
- Department of Physics, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, Punjab, 140001, India.
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Zarubin VA, Li TD, Humagain S, Ji H, Yager KG, Greenbaum SG, Vuong LT. Improved Anisotropic Thermoelectric Behavior of Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) via Magnetophoresis. ACS OMEGA 2018; 3:12554-12561. [PMID: 31457990 PMCID: PMC6644634 DOI: 10.1021/acsomega.8b00999] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 09/20/2018] [Indexed: 06/10/2023]
Abstract
There is strong demand for achieving morphological control of conducting polymers in its many potential applications, from energy harvesting to spintronics. Here, the static magnetic-field-induced alignment of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) particles is demonstrated. PEDOT:PSS thin films cast under modest mT-level magnetic fields exhibit a fourfold increase in the Seebeck coefficient and doubled electrical conductivity. Atomic force microscopy measurements confirm the presence of conducting islands that exhibit a 10-fold increase in the local charge carrier mobility and threshold behavior that is associated with phase separation. High-resolution scanning electron microscopy identifies a consistent structural coil-to-rod transition, and three-dimensional time-of-flight secondary-ion mass spectrometry imaging shows that the rodlike structures coincide with PEDOT domains that generally align with the magnetic field and cluster on the outer surface. Grazing-incidence small-angle X-ray scattering, Raman spectra, electron paramagnetic resonance, and circular dichroism spectroscopy point to the physical nature of the magnetophoretic alignment, which is expected to occur via magnetic coupling of PEDOT domains with polaron modes. Because casting under mT-level magnetic fields increases the electrical conductivity and Seebeck coefficient of PEDOT:PSS thin films without additional dopants that commonly limit the thermoelectric performance, our research reveals that low-field magnetophoresis significantly influences the structure and corresponding physical properties of PEDOT:PSS. Our results also point to concerns that the presence of small external magnetic fields in laboratory settings may appreciably and inadvertently influence the PEDOT:PSS morphology during settling, drying, or annealing processes.
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Affiliation(s)
- Vera A. Zarubin
- Bronx
High School of Science, 75 W 205th Street, Bronx, New York 10468, United
States
| | - Tai-De Li
- Department
of Physics, City College of New York and Advanced Science Research
Center, Graduate Center of the City University
of New York, 85 St Nicholas
Terrace, New York 10031, United States
| | - Sunita Humagain
- Department
of Physics, Hunter College of the
City University of New York, 695 Park Avenue, New York, New York 10065, United
States
- Department
of Physics, Graduate Center of the City
University of New York, 365 5th Avenue, New York, New York 10016, United
States
| | - Haojie Ji
- Department
of Physics, Queens College of the
City University of New York, 65-30 Kissena Blvd, Flushing, New York 11367, United
States
| | - Kevin G. Yager
- Center
for Functional Nanomaterials, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Steven G. Greenbaum
- Department
of Physics, Hunter College of the
City University of New York, 695 Park Avenue, New York, New York 10065, United
States
- Department
of Physics, Graduate Center of the City
University of New York, 365 5th Avenue, New York, New York 10016, United
States
| | - Luat T. Vuong
- Department
of Physics, Queens College of the
City University of New York, 65-30 Kissena Blvd, Flushing, New York 11367, United
States
- Department
of Physics, Graduate Center of the City
University of New York, 365 5th Avenue, New York, New York 10016, United
States
- Department
of Mechanical Engineering, University of
California at Riverside, Bourns Hall, Riverside, California 92521, United States
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