Preparation of Colloidal Boehmite Needles by Hydrothermal Treatment of Aluminum Alkoxide Precursors

Buining, Paul A.; Pathmamanoharan, C.; Jansen, J. Ben H.; Lekkerkerker, H.N.W.

doi:10.1111/j.1151-2916.1991.tb04102.x

Cited by 152 publications

(113 citation statements)

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“…Incidentally, γ-AlO(OH) is named boehmite after Böhm [11], although he denoted it as bauxite at the time of his collaboration with Zocher around 1925. Inspired by Zocher & Török's [22] and Bugosh's [23] work in the early 1960s, Buining et al [42] explored the preparation of colloidal boehmite rods by hydrothermal treatment of aluminium alkoxide precursors in the early 1990s. Colloidal boehmite rods with an average particle length L between approximately 100 and 400 nm (controlled by varying the initial amounts of alkoxide and acid) and aspect ratio L/D varying from 10 to 30 were obtained in this way, showing (some) polydispersity in both the particle length and diameter.…”

Section: Ii) Selected Systems Of Rod-like Particlesmentioning

confidence: 99%

“…The mineral gibbsite (γ-Al(OH) 3 ) is an important intermediate in the Bayer process for aluminium production in the form of agglomerates of small crystals. Starting from the materials used in the Buining method [42] to produce boehmite rods, Wierenga et al [56] discovered a synthesis route which yields well-formed hexagonal plate-like gibbsite crystals (diameter 100-200 nm and thickness 5-15 nm). Subsequently, van der Kooij & Lekkerkerker [57] succeeded in sterically stabilizing these gibbsite platelets by grafting a layer of low-molecular-weight PIB molecules onto their surface following the method of Buining & Lekkerkerker [36].…”

Section: Colloidal Silica Rodsmentioning

confidence: 99%

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Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

Lekkerkerker

Vroege

2013

Phil. Trans. R. Soc. A.

128

104

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A review is given of the field of mineral colloidal liquid crystals: liquid crystal phases formed by individual mineral particles within colloidal suspensions. Starting from their discovery in the 1920s, we discuss developments on the levels of both fundamentals and applications. We conclude by highlighting some promising results from recent years, which may point the way towards future developments.

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Section: Ii) Selected Systems Of Rod-like Particlesmentioning

confidence: 99%

Section: Colloidal Silica Rodsmentioning

confidence: 99%

Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

Lekkerkerker

Vroege

2013

Phil. Trans. R. Soc. A.

128

104

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“…The colloidal host rods, coded B1S3, were prepared by coating boehmite ͑␥-AlOOH͒ cores 21 having an average length of 194 nm and diameter of 9 nm with a 4.5 nm thick silica shell according to the procedure of van Bruggen et al 22 Figures 1͑a͒ and 1͑b͒ show typical transmission electron microscopy ͑TEM͒ images of the rods. The number averaged length L and diameter D of the rods determined from TEM are 203Ϯ93 nm and 18Ϯ3 nm, respectively ͓Figs.…”

Section: A the Colloidal Model Systemmentioning

confidence: 99%

Rotational dynamics of colloidal tracer spheres in suspensions of charged rigid rods

Koenderink

Aarts

Philipse

2003

The Journal of Chemical Physics

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The short-time rotational dynamics of colloidal silica tracer spheres in suspensions of rigid silica rods is investigated, using time-resolved phosphorescence anisotropy, as a function of tracer radius a T , rod volume fraction , and the range Ϫ1 of the double-layer repulsions between the like-charged rods and tracer spheres. A large tracer size a T and a small screening length Ϫ1 appear to maximize hydrodynamic hindrance of tracer diffusion for given . The marked -dependence of the rotational dynamics is primarily determined by the large excluded volumes of the high-aspect ratio rods. Stokes-Einstein-Debye ͑SED͒ scaling of the rotational diffusion coefficients with the inverse viscosity of the rod suspensions holds fairly well, expect for small a T and large Ϫ1 . The ionic strength dependence of deviations from SED scaling is rationalized in terms of an effective hard-rod model with the bare length L replaced by an effective length Lϩ4 Ϫ1 .

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“…A more detailed description of the synthesis of these suspensions can be found in Refs. [16,17] for boehmite and Refs. [6,18,19] for gibbsite.…”

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confidence: 99%

Liquid-Crystalline Phase Behavior of a Colloidal Rod-Plate Mixture

2000

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The phase behavior of rod-plate mixtures was investigated using model systems containing unambiguously rod-and plate-shaped colloids. We find that the theoretically disputed biaxial nematic phase is unstable with respect to demixing into an isotropic and two uniaxial nematic phases. The phase behavior at very high densities is exceptionally rich and includes the coexistence of up to four different liquid crystalline phases, which stem from the coupling between the employed particle shapes and polydispersity. PACS numbers: 82.70.Dd, 64.70.Md The entropy-driven formation of the uniaxial nematic phase in suspensions of rodlike or platelike particles has been established in theory [1] and in simulations [2], as well as in experiments [3][4][5][6] in the course of this century. The probably even richer liquid crystalline phase behavior exhibited by mixtures of rodlike and platelike particles, on the other hand, is currently subject to debate. The central question here is whether or not there exists a so-called biaxial nematic in these mixtures, in which both rods and plates are orientationally ordered but in mutually perpendicular directions. In earlier theoretical studies this biaxial phase was found to be stable over a broad range of compositions [7][8][9][10]. Recent theoretical study [11] and simulations [12] show that, at least in some cases, the biaxial phase may be unstable with respect to demixing into two separate uniaxial phases of predominantly rods and plates, respectively. On the part of experimental evidence, indications for biaxiality have been reported by Yu and Saupe [13] for a system containing both cylindrical and lamellar micelles. There is, however, some doubt [10,12] as to whether their observations are indicative of a biaxial phase transition or rather relate to a change in shape of the inherently "soft" micelles. In principle, model systems of inorganic colloids give the opportunity to study the phase behavior of unambiguously rodlike and platelike particles. In fact, the first experimental evidence for a uniaxial nematic phase was observed already in the 1920s in a suspension of inorganic vanadium pentoxide rods by Zocher [3]. However, a corresponding hard plate model system, i.e., consisting of particles with a short range repulsive interaction which seems crucial for exhibiting the unhindered isotropic to nematic ͑I-N͒ phase transition [14,15], has been lacking until recently. In this study we adopt a novel model system of platelike colloids which does show the I-N transition in its unmixed form [6]. Combining this system with its rodlike analog allows us to investigate the liquid crystalline phase behavior of a mixture of such plainly rod-and plate-shaped particles.The origin of liquid crystal stability in hard rod/plate mixtures is closely related to the case of the pure components, i.e., for rods and plates separately. Such spontaneous alignment in systems of nonattracting anisometric particles, which may seem counterintuitive at first thought, was first explained by Onsager [1] in th...

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Preparation of Colloidal Boehmite Needles by Hydrothermal Treatment of Aluminum Alkoxide Precursors

Cited by 152 publications

References 10 publications

Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

Rotational dynamics of colloidal tracer spheres in suspensions of charged rigid rods

Liquid-Crystalline Phase Behavior of a Colloidal Rod-Plate Mixture

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