Magnetic Orientation of Isotactic Polystyrene

Ezure, Hidetoshi; Kimura, Tsunehisa; Ogawa, Shuntaro; Ito, Eiko

doi:10.1021/ma970077g

Cited by 69 publications

(54 citation statements)

References 21 publications

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“…Magnetic field induced alignment was reported in 1998; 19 a 2.4 T magnetic field was imposed on a diblock copolymer comprising both block chains of liquidcrystalline polymers, resulting in a weak orientation order. Similar alignment has also been demonstrated for semicrystalline polymers in the presence of a strong magnetic field of 30 T. [20][21][22][23] Due to the small interaction energies magnetic reorientation requires immense fields that are technologically unrealistic. Here we demonstrate that low magnetic field annealing of a directed assembly of a homogeneous diblock copolymer with multiferroic Pb 1.1 ͑Zr 0.53 Ti 0.47 ͒O 3 ͑PZT͒ and CoFe 2 O 4 ͑CFO͒ precursors produces a well-developed selforganized two-dimensional ͑2D͒ "onion" nanostructure.…”

supporting

confidence: 63%

Self-organized two-dimensional onions

Ren

Briber

Wuttig

2009

Applied Physics Letters

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Spontaneously self-assembled onion-type nanostructures based on block copolymers as templating materials are reported. Polystyrene-poly͑ethylene oxide͒ diblock copolymer containing CoFe 2 O 4 and Pb 1.1 ͑Zr 0.53 Ti 0.47 ͒O 3 precursors segregated to the two microdomains forms well-ordered templated lamellar structures. Onion-type nanostructures have been induced by room temperature solvent annealing for 64 h in a magnetic field of 0.8 T oriented perpendicularly to the plane of film. The recorded images suggest that the Lorentz force acting on charges in the paraelectric precursor induces a circular component of the diffusion flux that leads to the onion formation. This templating process opens a route for nanometer-scale patterning of magnetic toroids. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3101373͔ Block copolymers have attracted much attention as prominent systems for nanotechnological applications because of their ability to spontaneously develop patterns on a nanoscale based on self-assembly. [1][2][3][4] Currently, a great deal of attention is being paid to the synthesis of complex nanostructured inorganic-organic hybrid materials. 5-10 A typical approach is the use of organic structures formed through self-assembly as structure directing agents. The final morphology is then determined by the cooperative organization of inorganic and organic molecular species into threedimensionally structured arrays. 11 In thin films, in addition to composition and molecular weight, the domain structure is also dependent on the surface energies of the blocks and on geometrical constraints introduced by the film. A recent example of inorganic-organic hybrid templating is the fabrication of ultrahigh density ferromagnetic nanocylinders that are embedded in a piezoelectric matrix by utilizing a precursorcontaining polystyrene-block-polyethylene oxide block copolymer. 12 The morphology and orientations of microdomains are the key factors controlling the properties of the patterned materials. The limited control over order and orientation of the microdomain in thin films poses restrictions on possible usages of patterning innovative material configurations via block copolymers. 13 Recent work demonstrates the alignment of block copolymers by electromagnetic fields. 14,15 Electric field induced alignment has been shown to be especially useful in thin film systems in which the two blocks have different dielectric constants. It does, however, require special sample geometries and surface preparation in the form of electrodes and patterned surfaces. Ultimately, dielectric breakdown limits the applicability of electric fields to alter block copolymeric patterns. [16][17][18] Magnetic fields should in principle also lead to spatial reorientations of copolymer blocks. They are attractive as no limitations to the field strength and sample configuration exist. Magnetic field induced alignment was reported in 1998; 19 a 2.4 T magnetic field was imposed on a diblock copolymer comprising both block chains of liquidcrystallin...

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supporting

confidence: 63%

Self-organized two-dimensional onions

Ren

Briber

Wuttig

2009

Applied Physics Letters

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“…The alignment seems to become difficult if the molecular weight is increased. However, iPS 92 of the nominal molecular weight of 400000 aligns. These observations do not seem to be interpreted simply in terms of viscosity effect.…”

Section: General Viewmentioning

confidence: 98%

“…The same conclusion is drawn for PEN 91 and iPS. 92 The sample crystallized up to 60 min exhibits crystal peaks. Azimuthal scans of the diffractions for (010), (110), and (100) of this sample are shown in Figure 15.…”

Section: Magnetic Alignment Of Poly(ethylene Terepthalate)mentioning

confidence: 98%

“…Nor may they align in their solid states (glassy and semi-crystalline states) because the viscosity is too high. However, we have found that many crystalline polymers including poly(ethylene-2,6-naphthalate) (PEN), 90,91 isotactic polystyrene (iPS), 92 isotactic polypropylene (iPP), 93 poly(ethylene terephthalate) (PET), 94 paraffin, 95,96 poly(ethylene oxide) (PEO) 97 polyetherester, 98 poly(carbonate) (PC), 99 and cellulose triacetate (CTA), 100 align magnetically under appropriate conditions.…”

Section: General Viewmentioning

confidence: 99%

“…Our study on iPS indicates that the crystallization is accelerated. 92 The lamella perfection of iPS is higher when crystallization is carried out in the magnetic field. 39 The interpretation of these observations might be related to the third comment.…”

Section: General Viewmentioning

confidence: 99%

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Study on the Effect of Magnetic Fields on Polymeric Materials and Its Application

Kimura

2003

Polym J

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236

206

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ABSTRACT:This paper reviews our recent work on the use of magnetic fields to the polymer processing. Polymers considered in this paper are not peculiar ones synthesized specially for the purpose of magnetic processing, but they are very usual ones including poly(ethylene terephthalate), polypropylene, etc. In this paper, two main magnetic effects on polymers are considered, i.e., alignment and levitation. In the first part, the magnetic torque causing the alignment is described. Then, examples of alignment in polymeric systems are presented, starting from simple cases such as magnetic alignment of fibers in a suspension to more complicated cases such as magnetic alignment of crystalline polymers in which mesophase formations and memory effects are involved. In the second part, the magnetic force acting on diamagnetic materials and its application to separation and processing of polymeric materials is described.KEY WORDS Diamagnetism / Magnetic Alignment / Magnetic Levitation / Phase Transition / Crystalline Polymers / Polymer Processing / Fiber / Magnetic effects on diamagnetic materials have been known since the age of Faraday, but it is very recent that the attention has been paid to the use of these effects to the processing of diamagnetic materials including inorganic, organic, and polymeric materials. This trend is partially due to the development of superconducting technology 1 that enables us to use high magnetic fields (10 T or more) in the study of materials science at individual laboratory level. Cryogen free (liquid-helium free) superconducting magnets, mostly manufactured by Japanese companies, are now on the market, with various types including a large bore type (45 cm at 3.5 T), a rotate bore type, a split type, a low fringe field type, a high field type (15 T, 52 mm in diameter), etc. These magnets are used in academia as well as industries for the processing purposes.High magnetic fields provided by these superconducting magnets have made it possible to visualize the magnetic effects on "non-magnetic" materials such as diamagnetic materials. Because the diamagnetism is very small compared to the ferromagnetism, we hardly experience in daily life the effects of magnetic field on plastics, water, and living bodies, etc. Some means must be devised to visualize these effects. A straightforward way is to use high magnetic fields. If we use a superconducting magnet of 10 T instead of an electromagnet generating 1 T, a small change of 1 mm is magnified to 10 cm and a phenomenon that takes a day to occur is completed in 15 min, because the magnetic effect is proportional to the square of the magnetic flux density. Diamagnetic levitation 2-4 and Moses effect 5 (water surface splits in a high magnetic field) are good examples among many others. [6][7][8][9] The magnetic effect on chemical reactions 10-12 is one of the major fields in magnetic researches, but in this paper we are concerned with the magnetic force and the magnetic torque acting on diamagnetic materials. The origin of the diamagnetism is the ...

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