Electrorheological properties of poly(acene quinone) radical suspensions

Choi, Hyoung Jin; Cho, Min S.

doi:10.1002/(sici)1099-1581(199711)8:11<697::aid-pat703>3.0.co;2-x

Cited by 36 publications

(17 citation statements)

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“…Anhydrous ER materials have some advantages such as system simplicity, reduced device corrosion, a relatively low current density, and a lower thermal coefficient of conductance, which may facilitate expanding the operating temperature range of ER activity. [7] Anhydrous ER fluids which have been demonstrated to be intrinsically active include suspensions of alumino-silicates, [7,8] carbonaceous materials, [9,10] and polymeric semiconductors such as polyaniline, [11,12] polypyrrole, [13][14][15] poly(acene quinone) radicals, [2,12,16] and oxidized polyacrylonitrile. [17][18][19][20] From the comprehensive researches on ER fluids, a number of mechanisms have been proposed to explain the origin of attractive forces induced between dispersed particles.…”

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confidence: 99%

Preparation and Electrorheological Characterization of Suspensions of Monodisperse Micron‐Sized Styrene–Acrylonitrile Copolymer Particles

Jun

Uhm

Suh

2003

Macro Chemistry & Physics

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IntroductionThe electrorheological (ER) effect of fluids, first reported by Winslow [1] in 1949, has been extensively studied for the past two decades and reviewed in several publications. [2][3][4][5][6] Typical ER fluids are suspensions that consist of polarizable solid particles dispersed in a nonconducting medium. When an external electric field of several kV/mm À1 is applied on this system, the immediately polarized suspension particles orient along the electric field direction and connect themselves into chains or columns spanning the gap between the two opposite electrodes. This change in the suspension structure strongly affects the rheological properties of the fluid. On the other hand, the viscosity of the fluids recovers the original state promptly by removing the applied field. This switching ability of ER fluids by electric field, together with the rapidity of the structural and rheological interconversion, renders them not only of academic interest but also of practical importance with potential applications, including electrical clutches, locks, valves, shock absorbers, sensors, tactile displays and so on.Many researchers investigated extensively a variety of dispersions for ER effect. Most of the ER suspensions reported in early period were water-activated systems, in which water or some other polar activator is originally considered necessary for the ER effect. Thus, the hydrous ER fluids possess their own various weak points, especially a limited operating temperature due to the loss of adsorbed Full Paper: Monodisperse micron-sized styrene-acrylonitrile copolymer (SAN) particles were prepared by a seeded swelling and polymerization method. Polystyrene particles prepared by dispersion polymerization were used as the seed latex. Characteristics of the particles were examined by scanning electron microscopy, FT-IR spectroscopy, 1 H NMR spectroscopy, thermogravimetric analysis and dielectric analysis, then the electrorheological (ER) behavior of the particle suspensions in silicone oil was investigated. The polarization ability of particles represented by the particle dipole coefficient increased greatly with the degree of hydrolysis of the nitrile component of SAN particles. As the acrylonitrile content of the copolymer particles was increased, the hydrolyzed particles exhibited higher dipole coefficients and, consequently, increased ER properties. Also, the effect of particle size on ER properties was studied by varying the size of these monodisperse copolymer particles.SEM photographs of nonhydrolyzed SAN50 microspheres (a) and the corresponding hydrolyzed SAN50 microspheres (b).water. For the recent decade, water-free ER fluids have been widely developed in order to overcome the disadvantages of aqueous systems. Anhydrous ER materials have some advantages such as system simplicity, reduced device corrosion, a relatively low current density, and a lower thermal coefficient of conductance, which may facilitate expanding the operating temperature range of ER activity. [7] Anhydrous ER fluids which...

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confidence: 99%

Preparation and Electrorheological Characterization of Suspensions of Monodisperse Micron‐Sized Styrene–Acrylonitrile Copolymer Particles

Jun

Uhm

Suh

2003

Macro Chemistry & Physics

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“…[30] Naphthalene (Junei Chemical Co., Japan) and phthalic anhydride (Duksan Pure Chemical Co, Korea) were used as monomers, and zinc chloride (ZnCl; Duksan Pure Chemical Co, Korea) was used as a catalyst in a Friedel-Crafts acylation process with naphthalene and phthalic anhydride. The polymerizations were placed in an inert gas environment, as described by Choi et al [29] The reaction temperature was kept at 250 8C. Polymerization was complete after 24 h. The schematic for the reaction pathway is illustrated in Scheme 1.…”

Section: Materials Synthesis and Characterizationmentioning

confidence: 99%

“…The peaks indicate an ether linkage of the phthalic anhydride at 920 cm -1 , absent in the spectrum of PNQR, which indicates that the polymerization reaction is complete. Note that Choi et al [29] performed thermogravimetric analysis to obtain density data for PNQRs, which unfortunately is difficult to characterize due to insolubility and infusibility of PNQR particles in most solvents. Scheme 1.…”

Section: Materials Synthesis and Characterizationmentioning

confidence: 99%

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Synthesis and Electrorheology of Semiconducting Poly(naphthalene quinone) Radical Particles

Sohn

Cho

Choi³

2002

Macromol. Chem. Phys.

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“…PANI derivatives and composites are being used for ER applications. This reversible fibrillation of particles due to the electric field produces a significant increase in apparent viscosity [8,9]. ER fluids have been the subject of intense theoretical and experimental research due to their emerging technological applications, such as clutches, vibration dumpers, robotics, hydraulics, shock absorbers, ER valves, couplings, and automotive industries [10,11].…”

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confidence: 99%

Synthesis and electrorheological properties of polyaniline/silicon dioxide composites

2012

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This study was to synthesize the inherently conductive polymer polyaniline using an optimized process to prepare polyaniline/silicon dioxide (PANI/SiO 2 ) composites by in situ polymerization and ex situ solution mixing. PANI and PANI/SiO 2 composite films were prepared by drop-by-drop and spin-coating methods. The morphology of particles and films were examined by a scanning electron microscope (SEM). SEM measurements indicated that the SiO 2 were well-dispersed and isolated in composite films. The electrorheological (ER), characteristics of the PANI/SiO 2 composites were investigated. A volume fraction series (u = 5-25 %) of the PANI/SiO 2 / silicone oil dispersions were prepared and sedimentation stabilities were determined. An ER activity was observed from the samples, when subjected to external electric field strength thus, they were classified as smart materials. Some parameters affecting the ER properties of the dispersions such as volume fraction, shear rate, electric field strength, frequency, and temperature were investigated.

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Electrorheological properties of poly(acene quinone) radical suspensions

Cited by 36 publications

References 11 publications

Preparation and Electrorheological Characterization of Suspensions of Monodisperse Micron‐Sized Styrene–Acrylonitrile Copolymer Particles

Preparation and Electrorheological Characterization of Suspensions of Monodisperse Micron‐Sized Styrene–Acrylonitrile Copolymer Particles

Synthesis and Electrorheology of Semiconducting Poly(naphthalene quinone) Radical Particles

Synthesis and electrorheological properties of polyaniline/silicon dioxide composites

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