Different approaches to analyze the dipolar interaction effects on diluted and concentrated granular superparamagnetic systems

Londoño, Oscar Moscoso; Tancredi, Pablo; Muraca, Diego; Zélis, P. Mendoza; Coral, Diego Fernando; Raap, M. B. Fernández van; Wolff, Ulrike; Neu, V.; Damm, Christine; Oliveira, C. L. P.; Pirota, K. R.; Knobel, M.; Socolovsky, L.M.

doi:10.1016/j.jmmm.2016.12.019

Cited by 45 publications

(33 citation statements)

References 89 publications

(138 reference statements)

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“…listes the coercive field values (Hc) extracted from the M vs. H curves obtained at 2K. For both systems (S and SG) it can be noticed that H C tends to higher values as the temperature decrease, which is an experimental evidence that the NPs are in the blocked regime at 2 K consistent with ZFC and FC results[59,73]. Furthermore, for each nanoparticle concentration, lower values of H C can be observed for plasticized samples (SG) in comparison to the other ones.…”

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confidence: 80%

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Structural analysis of magnetic nanocomposites based on chitosan

et al. 2018

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This work investigates the structure and magnetic properties of chitosan based films with different contents of magnetic nanoparticles (MNPs) of around 10 nm as well as the effects of the addition of glycerol as plasticizer. Synthesized MNPs were dispersed in the chitosan film forming solution by ultrasonication and then composite films were obtained by casting. From the morphological analysis, a bimodal distribution of clusters was detected; the larger ones seem to be present mostly in the plasticized samples. Regarding the mechanical behavior of the samples, for the non-plasticized samples the outstanding increase in modulus and strength with the increasing content of MNP was explained by a strong interfacial adhesion and very good particles dispersion into the chitosan matrix. This fact was also supported by the model applyed to the strength as a function of the volume fraction of MNP. Regarding magnetic properties, all nanocomposite films evidenced systems with particles of strong dipolar interactions that lead to blocking and irreversibility temperatures close to room temperature (RT). Even though the isothermal magnetization results showed that the particles in the nanocomposite films behave as super-paramagnetic at the highest analyzed temperature (RT), Langevin model as well as FESEM and SAXS analysis supported the hypothesis that the formation of aggregates with different features dominates the magnetic response through collective behavior, mainly in the plasticized films.

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supporting

confidence: 80%

“…ultra-dispersed systems). This deviation can be attributed to the scattering interference between the neighboring iron oxide NPs, denoting their aggregation into the films [58,59].…”

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confidence: 99%

Structural analysis of magnetic nanocomposites based on chitosan

et al. 2018

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“…The scattering intensity profiles for every investigated sample, presented in a log–log plot, are displayed in Figure S4, Supporting Information. All of the scattering patterns seem to follow similar trends, which are characteristic of systems composed by polydisperse nanoparticles and their aggregates . That is, at the low‐ q region, the scattering intensity follows a particular power law, instead of the Guinier behavior for individual and non‐interacting nanoparticles, indicating the formation of aggregates of MNPs within the matrices.…”

Section: Resultssupporting

confidence: 73%

“…As it can be noted (Figure S4, Supporting Information), a power law of I ( q < 0.1 nm −1 ) ∼ q −2.7 was found for the matrix loaded with 10 wt.% of magnetic nanoparticles, with the exponent progressively decreasing until reaching a scattering intensity dependence of ≈ q −1.8 in the samples with lower amount of magnetic nanoparticles. This behavior can be explained as the result of the formation of more compact and possibly larger aggregates as the nanoparticle concentration increases, as it was observed in previous works …”

Section: Resultsmentioning

confidence: 99%

Magnetic Remote Activation of Shape Recovery in Nanocomposites Based on Tung Oil and Styrene

Meiorin

Actis

Montoro

et al. 2018

Physica Status Solidi (a)

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The activation of unconstrained shape recovery in bio‐based polymeric nanocomposites is successfully achieved using magnetic nanoparticle heating. The materials investigated in this work present several distinct physical and chemical characteristics worth pointing out: they can be deformed and the original shape can be recovered by remotely heating the samples above their switching temperature, which is determined by their glass transition temperatures. Also, their chemical composition is largely based on biomass (the polymeric matrix contains more than 50 wt.% of raw tung oil). Magnetic heating performance is strongly affected by both the physical properties and the concentration of the nanoparticles loaded into the matrix. The concentration of nanoparticles is associated with the formation of agglomerates or clusters, which determines the dipolar interactions among the nanoparticles. The particles used in this work are able to absorb enough energy from an alternating magnetic field to heat the matrix and initiate the shape recovery. Although the sample with the highest content of magnetic solute (10 wt.%) presents the highest degree of agglomeration, it is also the sample with the best remote activation of shape recovery, according to the temperature reached under magnetothermal measurements and the time of actuation.

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“…70 Entretanto 70 Este comportamento magnético ocorre principalmente pelo modo de análise das curvas de magnetização, amostra em pó seco contendo apenas surfactantes na superfície, ou seja, há uma maior proximidade entre as partículas. 73 De fato, ao analisar a equação da energia de interação dipolar ( , ) entre duas partículas e , cada qual com seu momento magnético e , respectivamente, e separadas por uma distância ⃗ , pode-se observar que o aumento da distancia ⃗ leva exponencialmente a uma menor intensidade dessa interação, Equação [19]. 74,75 Contudo, esta equação também evidencia que a interação dipolar é maior quanto maior for o momento magnético das partículas.…”

Section: Dhkl (å)unclassified

Síntese de nanoestruturas core/shell de Co/Au magnetoplasmônica e pontos quânticos de CdSe/ZnS

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Different approaches to analyze the dipolar interaction effects on diluted and concentrated granular superparamagnetic systems

Cited by 45 publications

References 89 publications

Structural analysis of magnetic nanocomposites based on chitosan

Structural analysis of magnetic nanocomposites based on chitosan

Magnetic Remote Activation of Shape Recovery in Nanocomposites Based on Tung Oil and Styrene

Síntese de nanoestruturas core/shell de Co/Au magnetoplasmônica e pontos quânticos de CdSe/ZnS

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