The anisotropic properties of magnetically ordered gel

Yamamoto, Ichiro; Saito, Syuji; Makino, T.; Yamaguchi, M.; Takamasu, T.

doi:10.1016/j.stam.2006.02.003

Cited by 15 publications

(8 citation statements)

References 7 publications

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“…Chemically cross-linked poly(Nisopropylacrylamid) forms aligned network structure perpendicular to magnetic field [10]. Physically cross-linked agarose gels also show the perpendicular alignment [11]. In case side-chain group prefers the parallel alignment, polymer chain align perpendicularly to the magnetic field because the side-chain group is basically normal to the main chain.…”

Section: Introductionmentioning

confidence: 99%

Structural anisotropy of silica hydrogels prepared under magnetic field

2008

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Birefringence measurements have been carried out on the Pb-doped silica hydrogels prepared under various magnetic fields up to 5T. The silica gels prepared at 5T were used as a medium of crystal growth of PbBr2, whose result implied the structural anisotropy; an aligned array of crystallites was obtained by transmission electron microscopy. While the samples prepared at 0, 1, and 3T have no birefringence, we found that the samples have negative birefringence on the order of magnitude 10 −6 as if the direction of the magnetic field is the optic axis of a uniaxal crystal. To the authors' knowledge, the birefringent silica hydrogels were obtained by gelation under magnetic field for the first time. Also, scanning microscopic light scattering experiments have been performed. The results indicate that the characteristic length distribution for birefringent samples is narrower than that for non-birefringent ones.

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Section: Introductionmentioning

confidence: 99%

Structural anisotropy of silica hydrogels prepared under magnetic field

2008

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“…Chemically cross-linked poly(N-isopropylacrylamid) forms aligned network structure perpendicular to the magnetic field [14]. Physically cross-linked agarose gels also exhibit the perpendicular alignment [15]. If side-chain groups prefer the parallel alignment, main chains align perpendicularly.…”

Section: Introductionmentioning

confidence: 99%

Reconsideration on structural anisotropy of silica hydrogels prepared in magnetic field

Mori

Kaito

Furukawa

2015

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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In a previous paper [A. Mori, T. Kaito, H. Furukawa, Mater. Lett. 62 (2008) 3459-3461], we carried out birefringence measurements of Pb(II)-doped silica hydrogels prepared in a magnetic field (B). For a 5T sample, we observed a negative birefringence with the optic axis along B. At that time, providing a positive intrinsic birefringence of silica, we speculated that in the birefringent gels the gel network extended perpendicular to B. The purpose of this paper is to reconsider this speculation on the basis of previous and recent results [T. Kaito, S.-i. Yanagiya, A. Mori, M. Kurumada, C. Kaito, T. Inoue, J. Cryst. Growth 289 (2006) 275-277; T. Kaito, A. Mori, C. Kaito, J. Chem.Chem. Eng., 9 (2015) 61-66]. In the former, the silica gels were used as a medium of a crystal growth of PbBr 2 and aligned arrays of crystallites with long axis parallel to B were obtained. In the latter, Pb(II) nanocrystallites were formed in silica xerogels by electron irradiation. Both of the short axis of PbBr 2 crystallites and the diameter of Pb(II) crystallites were a few tens of nanometers. This size must be a size of short axis of pores in the gel networks elongated affected by the magnetic field. Since the PbBr 2 crystallites were elongated along the magnetic field, we conclude that the Pb(II)-doped silica gel networks aligned along the magnetic field.

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“…Effect of a magnetic field applied during the gelation on the network structure of organic polymer gels was studied. Alignment perpendicular to the magnetic field occurred for poly(N-isopropylacrylamid) gels [14] and agarose gels [15,16]. In cases side-chain group prefers the parallel alignment, polymer chains align perpendicularly to the magnetic field because the side-chain group is basically normal to the main chain.…”

Section: Introduction 1generalmentioning

confidence: 99%

Birefringence of silica hydrogels prepared under high magnetic fields reinvestigated

Mori,

Kaito,

Furukawa

et al. 2014

Preprint

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Birefringence is an indicator of structural anisotropy of materials. We measured the birefringence of Pb(II)-doped silica hydrogels prepared under a high magnetic field of various strengths. Because the silica is diamagnetic, one does not expect the structural anisotropy induced by a magnetic field. In previous work [Mori A, Kaito T, Furukawa H 2008 Mater. Lett. 62 3459-3461], we prepared samples in cylindrical cells made of borosilicate glass and obtained a preliminary result indicating a negative birefringence for samples prepared at 5T with the direction of the magnetic field being the optic axis. We have measured the birefringence of Pn(II)-doped silica hydrogels prepared in square cross-sectional cells made of quartz and reverted the previous conclusion. Interestingly, the magnetic-influenced silica hydrogels measured have been classified into four classes: two positive birefringent ones, no birefringent one, and negative birefringent one. Proportionality between birefringence and the strength of magnetic field is seen for the former two.

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The anisotropic properties of magnetically ordered gel

Cited by 15 publications

References 7 publications

Structural anisotropy of silica hydrogels prepared under magnetic field

Structural anisotropy of silica hydrogels prepared under magnetic field

Reconsideration on structural anisotropy of silica hydrogels prepared in magnetic field

Birefringence of silica hydrogels prepared under high magnetic fields reinvestigated

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