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Philip J. Magnetic nanofluids (Ferrofluids): Recent advances, applications, challenges, and future directions. Adv Colloid Interface Sci 2023; 311:102810. [PMID: 36417827 DOI: 10.1016/j.cis.2022.102810] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/28/2022] [Accepted: 11/05/2022] [Indexed: 11/16/2022]
Abstract
Impelled by the need to find solutions to new challenges of modern technologies new materials with unique properties are being explored. Among various new materials that emerged over the decades, magnetic fluids exhibiting interesting physiochemical properties (optical, thermal, magnetic, rheological, apparent density, etc.) under a magnetic stimulus have been at the forefront of research. In the initial phase, there has been a fervent scientific curiosity to understand the field-induced intriguing properties of such fluids but later a plethora of technological applications emerged. Magnetic nanofluid, popularly known as ferrofluid, is a colloidal suspension of fine magnetic nanoparticles, has been at the forefront of research because of its magnetically tunable physicochemical properties and applications. Due to their stimuli-responsive behaviour, they have been finding more applications in biology and other engineering disciplines in recent years. Therefore, a critical review of this topic highlighting the necessary background, the potential of this material for emerging technologies, and the latest developments is warranted. This review also provides a summary of various applications, along with the key challenges and future research directions. The first part of the review addresses the different types of magnetic fluids, the genesis of magnetic fluids, their synthesis methodologies, properties, and stabilization techniques are discussed in detail. The second part of the review highlights the applications of magnetic nanofluids and nanoemulsions (as model systems) in probing order-disorder transitions, scattering, diffraction, magnetically reconfigurable internal structures, molecular interaction, and weak forces between colloidal particles, conformational changes of macromolecules at interfaces and polymer-surfactant complexation at the oil-water interface. The last part of the review summarizes the interesting applications of magnetic fluids such as heat transfer, sensors (temperature, pH, urea detection, cations, defect detection sensors), tunable optical filters, removal of dyes, dynamic seals, magnetic hyperthermia-based cancer therapy and other biomedical applications. The applications of magnetic nanofluids in diverse disciplines are growing day by day, yet there are challenges in their practical adaptation as field-worthy or packaged products. This review provides a pedagogical description of magnetic fluids, with the necessary background, key concepts, physics, experimental protocols, design of experiments, challenges and future directions.
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Affiliation(s)
- John Philip
- Smart Materials Section, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, India.
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Pathak S, Verma R, Kumar P, Singh A, Singhal S, Sharma P, Jain K, Pant RP, Wang X. Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:3009. [PMID: 34835770 PMCID: PMC8620981 DOI: 10.3390/nano11113009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 01/03/2023]
Abstract
The present work reports the synthesis of a stable aqueous magnetic fluid (AMF) by dispersing double-surfactant-coated Fe3O4 magnetic nanoparticles (MNPs) in water using a facile ambient scalable wet chemical route. MNPs do not disperse well in water, resulting in low stability. This was improved by dispersing double-surfactant (oleic acid and sodium oleate)-coated MNPs in water, where cross-linking between the surfactants improves the stability of the AMFs. The stability was probed by rheological measurements and all the AMF samples showed a good long-term stability and stability against a gradient magnetic field. Further, the microwave spin resonance behavior of AMFs was studied in detail by corroborating the experimental results obtained from the ferromagnetic resonance (FMR) technique to theoretical predictions by appropriate fittings. A broad spectrum was perceived for AMFs which indicates strong ferromagnetic characteristics. The resonance field shifted to higher magnetic field values with the decrease in particle size as larger-size MNPs magnetize and demagnetize more easily since their magnetic spins can align in the field direction more definitely. The FMR spectra was fitted to obtain various spin resonance parameters. The asymmetric shapes of the FMR spectra were observed with a decrease in particle sizes, which indicates an increase in relaxation time. The relaxation time increased with a decrease in particle sizes (sample A to D) from 37.2779 ps to 42.8301 ps. Further, a detailed investigation of the structural, morphological, and dc magnetic properties of the AMF samples was performed. Room temperature dc magnetic measurements confirmed the superparamagnetic (SPM) characteristics of the AMF and the M-H plot for each sample was fitted with a Langevin function to obtain the domain magnetization, permeability, and hydrodynamic diameter of the MNPs. The saturation magnetization and coercivity of the AMF samples increased with the increase in dispersed MNPs' size of the samples. The improvement in the stability and magnetic characteristics makes AMFs suitable candidates for various biomedical applications such as drug delivery, magnetic fluid hyperthermia, and biomedicines.
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Affiliation(s)
- Saurabh Pathak
- Department of Mechanical Engineering, University of Melbourne, Parkville, VIC 3052, Australia
- School of Engineering, RMIT University, Melbourne, VIC 3001, Australia; (P.S.); (X.W.)
| | - Rajni Verma
- School of Physics, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Prashant Kumar
- School of Sciences, RMIT University, Melbourne, VIC 3001, Australia;
- Academy of Scientific and Innovative Research, CSIR-NPL Campus, New Delhi 110012, India; (A.S.); (K.J.); (R.P.P.)
| | - Arjun Singh
- Academy of Scientific and Innovative Research, CSIR-NPL Campus, New Delhi 110012, India; (A.S.); (K.J.); (R.P.P.)
| | - Sakshi Singhal
- Institute of Nuclear Medicine & Allied Sciences, DRDO, Brig SK Mazumdar Road, Delhi 110054, India;
| | - Pragati Sharma
- School of Engineering, RMIT University, Melbourne, VIC 3001, Australia; (P.S.); (X.W.)
- Academy of Scientific and Innovative Research, CSIR-NPL Campus, New Delhi 110012, India; (A.S.); (K.J.); (R.P.P.)
| | - Komal Jain
- Academy of Scientific and Innovative Research, CSIR-NPL Campus, New Delhi 110012, India; (A.S.); (K.J.); (R.P.P.)
| | - Rajendra Prasad Pant
- Academy of Scientific and Innovative Research, CSIR-NPL Campus, New Delhi 110012, India; (A.S.); (K.J.); (R.P.P.)
| | - Xu Wang
- School of Engineering, RMIT University, Melbourne, VIC 3001, Australia; (P.S.); (X.W.)
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Katsikis G, Breant A, Rinberg A, Prakash M. Synchronous magnetic control of water droplets in bulk ferrofluid. SOFT MATTER 2018; 14:681-692. [PMID: 29205244 DOI: 10.1039/c7sm01973d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We present a microfluidic platform for magnetic manipulation of water droplets immersed in bulk oil-based ferrofluid. Although non-magnetic, the droplets are exclusively controlled by magnetic fields without any pressure-driven flow. The fluids are dispensed in a sub-millimeter Hele-Shaw chamber that includes permalloy tracks on its substrate. An in-plane rotating magnetic field magnetizes the permalloy tracks, producing local magnetic gradients, while an orthogonal magnetic field magnetizes the bulk ferrofluid. To minimize the magnetostatic energy of the system, the water droplets are attracted towards the locations on the tracks where the bulk ferrofluid is repelled. Using this technique, we demonstrate synchronous generation and propagation of water droplets, study the kinematics of propagation, and analyze the flow of the bulk ferrofluid. In addition, we show controlled break-up of droplets and droplet-to-droplet interactions. Finally, we discuss future applications owing to the potential biocompatibility of the droplets.
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Affiliation(s)
- Georgios Katsikis
- Department of Mechanical Engineering, Stanford University, 450 Serra Mall, California 94305, USA
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Wang ZM, Wu RG, Wang ZP, Ramanujan RV. Magnetic Trapping of Bacteria at Low Magnetic Fields. Sci Rep 2016; 6:26945. [PMID: 27254771 PMCID: PMC4890591 DOI: 10.1038/srep26945] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 05/03/2016] [Indexed: 02/04/2023] Open
Abstract
A suspension of non-magnetic entities in a ferrofluid is referred to as an inverse ferrofluid. Current research to trap non-magnetic entities in an inverse ferrofluid focuses on using large permanent magnets to generate high magnetic field gradients, which seriously limits Lab-on-a-Chip applications. On the other hand, in this work, trapping of non-magnetic entities, e.g., bacteria in a uniform external magnetic field was studied with a novel chip design. An inverse ferrofluid flows in a channel and a non-magnetic island is placed in the middle of this channel. The magnetic field was distorted by this island due to the magnetic susceptibility difference between this island and the surrounding ferrofluid, resulting in magnetic forces applied on the non-magnetic entities. Both the ferromagnetic particles and the non-magnetic entities, e.g., bacteria were attracted towards the island, and subsequently accumulate in different regions. The alignment of the ferrimagnetic particles and optical transparency of the ferrofluid was greatly enhanced by the bacteria at low applied magnetic fields. This work is applicable to lab-on-a-chip based detection and trapping of non-magnetic entities bacteria and cells.
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Affiliation(s)
- Z M Wang
- School of Materials Science and Engineering, Nanyang Technological University 50 Nanyang Avenue, Singapore 639798, Singapore
| | - R G Wu
- Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075, Singapore
| | - Z P Wang
- Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075, Singapore
| | - R V Ramanujan
- School of Materials Science and Engineering, Nanyang Technological University 50 Nanyang Avenue, Singapore 639798, Singapore
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Felicia LJ, Philip J. Effect of hydrophilic silica nanoparticles on the magnetorheological properties of ferrofluids: a study using opto-magnetorheometer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3343-3353. [PMID: 25734232 DOI: 10.1021/acs.langmuir.5b00103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
For many technological applications of ferrofluids, the magnetorheological properties require being precisely controlled. We study the effect of hydrophilic silica on the magnetorheology of an oil-based ferrofluid containing Fe3O4 nanoparticles of size ∼10 nm. We observe that the presence of silica nanoparticles lowers the yield stresses, viscoelastic moduli, and shear thinning behavior of the ferrofluid because of the weakening of dipolar interactions, which was evident from the observed lower yield stresses exponent (<2). The ferrofluid containing silica exhibits a dominant elastic behavior, a reduced hysteresis during the forward and reverse magnetic field sweeps, and a longer linear viscoelastic regime under nonlinear deformation. The Mason number plots at low shear rates and magnetic fields show deviations from the master curve in the presence of silica. The magnetic field induced microstructures, visualized using opto-magnetorheometer, showed columnar aggregate structures along the field directions, which are reoriented along the shear flow direction at high shear rates. The image analysis shows that the average thickness of the columnar aggregates in pure ferrofluid is much larger than that of the mixed system, which suggests that the intervening silica matrix hampers the zippering transition of columns at higher magnetic field and shear rates. Our results suggest that optimization of rheological properties of ferrofluids is possible by carefully adding suitable silica nanoparticles, which may find practical applications such as dynamic seals, heat transfer, sensors, and opto-fluidic devices, etc.
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Affiliation(s)
- Leona J Felicia
- SMARTS, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
| | - John Philip
- SMARTS, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
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Passow C, Fischer B, Sprung M, Köckerling M, Wagner J. Direction-dependent freezing of diamagnetic colloidal tracers suspended in paramagnetic ionic liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7283-7288. [PMID: 24940991 DOI: 10.1021/la500658x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The dynamic behavior of an inverse ferrofluid consisting of diamagnetic, spherical silica particles suspended in the paramagnetic ionic liquid (EMIm)2[Co(NCS)4] is investigated by means of x-ray photon correlation spectroscopy in the presence of an external magnetic field. Dipole-dipole interactions between the diamagnetic holes in the paramagnetic continuum of the suspending medium induce a direction-dependence of the diffusive motion of the colloidal particles: due to a magnetic repulsion perpendicular to the direction of an external field the diffusive motion of the colloidal particles is selectively frozen in this direction.
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Affiliation(s)
- Christopher Passow
- Institut für Chemie, Universität Rostock , Albert-Einstein-Straße 3a, 18059 Rostock, Germany
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Felicia LJ, Philip J. Probing of field-induced structures and tunable rheological properties of surfactant capped magnetically polarizable nanofluids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:110-120. [PMID: 23210900 DOI: 10.1021/la304118b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Oil-based nanofluid containing surfactant-capped magnetite nanoparticles are synthesized by a simple coprecipitation approach, and their magnetorheological properties are studied for different magnetic field strengths and volume fractions. We observe a distinct "plateau-like region" in the shear thinning viscosity curve, under an external magnetic field, possibly due to a peculiar alignment of the chains with respect to the field direction where the structure is stable against fragmentation. The observed plateau regime is reminiscent to that of kinetically arrested gel networks. Interestingly, such a plateau regime has been observed only above certain critical magnetic field when the dipolar interaction strength is much greater than the thermal energy where the aggregation becomes a nonequilibrium transport-limited process. The good collapse of specific viscosity data against Mason number for different magnetic field strengths onto a single curve suggests the dominance of hydrodynamic and magnetic forces on thermal force above a certain magnetic field strength. The observed increase in both static and dynamic yield stresses under the magnetic field confirms the formation of columnar structures that hinder the flow behavior. The hysteresis observed in the magnetic sweep experiments shows the inability of the chains to relax within the measurement time. The dynamic measurements confirm that the field-induced structures impart elastic behavior to the dispersion, which is found to increase with magnetic field and saturates at higher field strengths.
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Affiliation(s)
- Leona J Felicia
- SMARTS, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India
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Soto-Aquino D, Rosso D, Rinaldi C. Oscillatory shear response of dilute ferrofluids: predictions from rotational Brownian dynamics simulations and ferrohydrodynamics modeling. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:056306. [PMID: 22181497 DOI: 10.1103/physreve.84.056306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Indexed: 05/31/2023]
Abstract
Ferrofluids are colloidal suspensions of magnetic nanoparticles that exhibit normal liquid behavior in the absence of magnetic fields but respond to imposed magnetic fields by changing their viscosity without loss of fluidity. The response of ferrofluids to constant shear and magnetic fields has received a lot of attention, but the response of ferrofluids to oscillatory shear remains largely unexplored. In the present work we used rotational Brownian dynamics to study the dynamic properties of ferrofluids with thermally blocked nanoparticles under oscillatory shear and constant magnetic fields. Comparisons between simulations and modeling using the ferrohydrodynamics equations were also made. Simulation results show that, for small rotational Péclet number, the in-phase and out-of-phase components of the complex viscosity depend on the magnitude of the magnetic field and frequency of the shear, following a Maxwell-like model with field-dependent viscosity and characteristic time equal to the field-dependent transverse magnetic relaxation time of the nanoparticles. Comparison between simulations and the numerical solution of the ferrohydrodynamic equations shows that the oscillatory rotational magnetoviscosity for an oscillating shear field obtained using the kinetic magnetization relaxation equation quantitatively agrees with simulations for a wide range of Péclet number and Langevin parameter but has quantitative deviations from the simulations at high values of the Langevin parameter. These predictions indicate an apparent elastic character to the rheology of these suspensions, even though we are considering the infinitely dilute limit in which there are negligible particle-particle interactions and, as such, chains do not form. Additionally, an asymptotic analytical solution of the ferrohydrodynamics equations, valid for Pe<<2, was used to demonstrate that the Cox-Merz rule applies for dilute ferrofluids under conditions of small shear rates. At higher shear rates the Cox-Merz rule ceases to apply.
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Affiliation(s)
- D Soto-Aquino
- Department of Chemical Engineering, University of Puerto Rico, Mayagüez, Mayagüez Puerto Rico
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Ramos J, de Vicente J, Hidalgo-Alvarez R. Small-amplitude oscillatory shear magnetorheology of inverse ferrofluids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9334-9341. [PMID: 20345105 DOI: 10.1021/la100252g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A comprehensive investigation is performed on highly monodisperse silica-based inverse ferrofluids under small-amplitude oscillatory shear in the presence of external magnetic fields up to 1 T. The effect of particle volume fraction and continuous medium Newtonian viscosity is thoroughly investigated. Experimental results for storage modulus are used to validate existing micromechanical magnetorheological models assuming different particle-level field-induced structures.
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Affiliation(s)
- Jose Ramos
- Biocolloid and Fluid Physics Group, Department of Applied Physics, Faculty of Sciences, University of Granada, C/ Fuentenueva s/n, 18071-Granada, Spain
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Saldivar-Guerrero R, Richter R, Rehberg I, Aksel N, Heymann L, Rodriguez-Fernández OS. Viscoelasticity of mono- and polydisperse inverse ferrofluids. J Chem Phys 2006; 125:084907. [PMID: 16965057 DOI: 10.1063/1.2337576] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on measurements of a magnetorheological model fluid created by dispersing nonmagnetic microparticles of polystyrene in a commercial ferrofluid. The linear viscoelastic properties as a function of magnetic field strength, particle size, and particle size distribution are studied by oscillatory measurements. We compare the results with a magnetostatic theory proposed by De Gans et al. [Phys. Rev. E 60, 4518 (1999)] for the case of gap spanning chains of particles. We observe these chain structures via a long distance microscope. For monodisperse particles we find good agreement of the measured storage modulus with theory, even for an extended range, where the linear magnetization law is no longer strictly valid. Moreover we compare for the first time results for mono- and polydisperse particles. For the latter, we observe an enhanced storage modulus in the linear regime of the magnetization.
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de Vicente J, López-López MT, Durán JDG, Bossis G. A slender-body micromechanical model for viscoelasticity of magnetic colloids: Comparison with preliminary experimental data. J Colloid Interface Sci 2005; 282:193-201. [PMID: 15576099 DOI: 10.1016/j.jcis.2004.08.128] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Accepted: 08/14/2004] [Indexed: 10/26/2022]
Abstract
The storage modulus, G', together with the yield stress, is an essential quantity characterizing the rheological properties of magnetic field-responsive suspensions (magnetorheological fluids or MRF). In this work, we present both experimental and theoretical results on the viscoelastic properties of MRFs. Two MRFs are used: In one the solid phase consists of cobalt ferrite particles + silica gel, with silicone oil as liquid phase. The second system is formed by carbonyl iron + silica gel also dispersed in silicone oil. The cobalt ferrite particles are synthesized as monodisperse colloidal spheres with an average diameter of 850 nm. We describe a new model based on the slender-body approach for hydrodynamic interactions. The predictions of the model are compared to preliminary experimental G' data obtained in a controlled stress plate-plate rheometer. It is found that the model gives the correct order of magnitude for the highest fields in iron suspensions, but underestimates the experimental results obtained in ferrite ones. In the case of high permeability materials such as carbonyl iron, by the inclusion of high-order multipolar interactions and saturation effects we also predict the order of magnitude of the experimental results. When dealing with low permeability cobalt ferrite based MRFs, other effects, such as remanence (at low fields) and saturation (at high fields), must be considered.
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Affiliation(s)
- J de Vicente
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, C/Fuentenueva s/n, 18071 Granada, Spain.
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Raşa M, Philipse AP, Jamon D. Initial susceptibility, flow curves, and magneto-optics of inverse magnetic fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:031402. [PMID: 14524764 DOI: 10.1103/physreve.68.031402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2002] [Revised: 04/15/2003] [Indexed: 05/22/2023]
Abstract
We introduce inverse magnetic fluids, consisting of gibbsite [Al(OH)(3)] platelets and alumina (Al2O3) spheres dispersed in a magnetic fluid, studied together with silica (SiO2) dispersions based on the same magnetic fluid matrix. Atomic force microscopy, optical microscopy, and alternate gradient magnetometry confirm the remarkable stability of the samples. Optical microscopy shows aggregation of nonmagnetic spheres, which, surprisingly, strongly depends on the concentration of the magnetic fluid rather than the concentration of nonmagnetic particles. Our model for the initial susceptibility of inverse magnetic fluids agrees very well with experimental data for systems containing spherical particles. The flow curves in an external magnetic field are strongly influenced by the aggregation of nonmagnetic particles or preformed nonmagnetic particle clusters, and by their disruption due to the shear flow. Static linear magnetobirefringence and magnetodichroism of all samples are investigated both experimentally and theoretically. These effects, which occur in all magnetic fluids, can be enhanced by the additional anisotropy due to the magnetic holes. The experiments we performed showed that, at a wavelength of 820 nm, the magnetodichroism is increased while the magneto-birefringence decreases when nonmagnetic particles were dispersed in the magnetic fluid. Magneto-birefringence is expected to be increased at large enough wavelengths only.
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Affiliation(s)
- M Raşa
- Van 't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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Islam MF, Lin KH, Lacoste D, Lubensky TC, Yodh AG. Field-induced structures in miscible ferrofluid suspensions with and without latex spheres. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:021402. [PMID: 12636674 DOI: 10.1103/physreve.67.021402] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2002] [Indexed: 05/24/2023]
Abstract
We explore magnetic-field-induced ordering and microphase separation of aqueous ferrofluid and of aqueous mixtures of ferrofluid with nonmagnetic latex spheres. The ferrofluid is a surfactant stabilized aqueous suspension of magnetite (Fe3O4) particles with average diameter 20 nm (including the approximately 2.5-nm thick surfactant layer); the nonmagnetic latex spheres are charge stabilized polymethylmethacrylate (PMMA) particles with diameters of 42 nm, 108 nm, and 220 nm. In the presence of a uniform magnetic field, needlelike ferrofluid droplets formed that eventually grew to sample-traversing columns at fields of approximately 600 G; the two-dimensional structure of these columns was, however, glassy rather than hexagonal. In higher fields, approximately 1000 G, the columns stretched and coalesced into sheetlike striped liquids, but a true lamellar phase was not observed. The addition of nonmagnetic latex spheres to the ferrofluid suspension lowered substantially the critical field for the formation of columns, and induced lamellar (stripe) phases at relatively low applied fields. Image analysis was used to determine the spatial correlation functions, the average needle or column spacing, and the average lamellae spacing of these samples as a function of latex sphere size and concentration.
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Affiliation(s)
- M F Islam
- Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, USA
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Bossis G, Volkova O, Lacis S, Meunier A. Magnetorheology: Fluids, Structures and Rheology. FERROFLUIDS 2002. [DOI: 10.1007/3-540-45646-5_11] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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de Gans BJ, Duin NJ, van den Ende D, Mellema J. The influence of particle size on the magnetorheological properties of an inverse ferrofluid. J Chem Phys 2000. [DOI: 10.1063/1.482011] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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