Role of initial precursors on the liquid-crystalline phase behavior of synthetic aluminogermanate imogolite nanotubes

Paineau, Erwan; Rouzière, Stéphan; Monet, Geoffrey; Diogo, Cristina Coelho; Morfin, Isabelle; Launois, Pascale

doi:10.1016/j.jcis.2020.07.036

Cited by 22 publications

(46 citation statements)

References 82 publications

(107 reference statements)

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“…Binder-free imogolite fibers were spun by injecting an aqueous spinning dope solution of DW Ge-INTs (9 g/L) through a needle into a coagulation bath of calcium chloride in water (300 g/L). The spinning dopes exhibited strong birefringence ( Figure S2 ), indicative of an ordered mesophase observed previously in both carbon and imogolite nanotube dispersions, 16 , 37 , 38 which should be ideal for liquid crystalline wet spinning. The high ionic strength of the coagulant ( I = 8.1 M) enabled the quick gelation of the spinning dope.…”

Section: Spinning Dw Ge-int Fiberssupporting

confidence: 62%

“… 7 , 8 However, a variety of INTs can be synthesized via sol–gel methods using different precursors, particularly ones with Ge substituting for Si, 9 in either a double-walled or single-walled form. 10 , 11 Similarly to solutions of CNT polyelectrolytes, 12 − 14 INTs form liquid crystalline mesophases, which can be reoriented either by electrical or flow fields, 15 , 16 potentially leading to highly aligned fibers. In contrast to CNTs, INT solutions are optically transparent, which greatly aids the use of polarized optical microscopy (POM) in their characterization.…”

Section: Introductionmentioning

confidence: 99%

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Continuous Binder-Free Fibers of Pure Imogolite Nanotubes

Moore

Paineau

Launois

et al. 2021

ACS Appl. Mater. Interfaces

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Imogolite nanotubes (INTs) display a range of useful properties and provide an ideal material system to study the assembly of nanomaterials into macroscopic fibers. A method of wet spinning pure, binder-free imogolite fibers has been developed using double-walled germanium imogolite nanotubes. The nanotube aspect ratio can be controlled during the initial synthesis and is critical to the spinning process. Fibers made from short nanotubes (<100 nm) have very low gel strengths, while dopes with longer nanotubes (500–1000 nm) are readily spinnable. The tensile behavior of the resulting imogolite nanotube fibers is strongly influenced by relative humidity (RH), with a modulus of 30 GPa at 10% RH compared to 2.8 GPa at 85% RH, as well as a change in failure mode. This result highlights the importance of inter-nanotube interactions in such assemblies and provides a useful strategy for further exploration. Interestingly, in the absence of a matrix phase, a degree of misorientation appears to improve load transfer between the individual INTs within the porous fiber, likely due to an increase in the number of interparticle contacts. Imogolite nanotubes are an appealing analogue to other nanotube fiber systems, and it is hoped that learnings from this system can also be used to improve carbon nanotube fibers.

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Section: Spinning Dw Ge-int Fiberssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Continuous Binder-Free Fibers of Pure Imogolite Nanotubes

Moore

Paineau

Launois

et al. 2021

ACS Appl. Mater. Interfaces

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“…The WAXS diagrams for R' = 1.8, 2 and 2.1 appear to be very similar ( Figure 3). As expected, they are also similar to those already measured and analyzed for Ge-DWINTs were previously synthesized using the same synthesis method and R' = 2 [39,42]. Minima positions below 1 Å −1 are characteristic of the form factor of Ge-DWINTs.…”

Section: Structural Properties Of Final Productssupporting

confidence: 84%

“…Some promising attempts have been reported by changing conventional heating (reflux or autoclave) with microwave irradiation, showing an increase in the length of the tubes [37,38]. A convenient and simple way to obtain highly anisometric Ge-DWINTs is to mix in one-step Ge and Al precursors in the presence of urea CO(NH 2 ) 2 ( Figure 1a) [39][40][41][42]. Ge-DWINTs obtained with this method are structurally identical to those achieved by NaOH hydrolysis [39] but the ratio between the length and the diameter of the nanotubes (aspect ratio) is large enough to allow them to form well-ordered liquid-crystalline phases [40].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Paineau

Launois

2020

Crystals

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Synthetic imogolite-like nanotubes (INT) with well-defined diameters represent a considerable opportunity for the development of advanced functional materials. Recent progress has made it possible to increase their aspect ratio and unique self-organization properties were evidenced. We suggest that slight modification of the synthesis conditions may drastically affect the resulting liquid-crystalline properties. In this work, we investigate how the precursor’s [Al]/[Ge] molar ratio (R’) impacts the morphology and the colloidal properties of aluminogermanate INTs by combining a multi-scale characterization. While only double-walled nanotubes are found for R’ ≥ 1.8, the presence of single-walled nanotubes occurs when the ratio is lowered. Except for the lowest R’ ratio investigated (R’ = 0.66), all synthetic products present one-dimensional shapes with a high aspect ratio. Small-angle X-ray scattering experiments allow us to comprehensively investigate the colloidal properties of the final products. Our results reveal that a liquid-crystalline hexagonal columnar phase is detected down to R’ = 1.33 and that it turns into a nematic arrested phase for R’ = 0.90. These results could be useful for the development of novel stimuli-responsive nanocomposites based-on synthetic imogolite nanotubes.

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“…Both sides of the imogolite NTs' cavities can be easily functionalized [25][26][27][28]. The synthetic flexibility of imogolite NTs leads to widely tunable properties, with exciting reports as regards the performance of imogolite NT for chemical separation [17,[20][21][22][23][24]26,29], co-photo-catalyst [30], hybrid nanocomposites [31] and colloidal, liquid-crystal applications [32][33][34][35]. In addition to these examples, the potential range of applicability for AlSi AlGe NTs has been recently expanded via synthesis of Fe-doped imogolite NTs, capable of absorbing visible (and UV) light.…”

Section: Introductionmentioning

confidence: 99%

Termination Effects in Aluminosilicate and Aluminogermanate Imogolite Nanotubes: A Density Functional Theory Study

et al. 2020

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We investigate termination effects in aluminosilicate (AlSi) and aluminogermanate (AlGe) imogolite nanotubes (NTs) by means of semi-local and range-corrected hybrid Density Functional Theory (DFT) simulations. Following screening and identification of the smallest finite model capable of accommodating full relaxation of the NT terminations around an otherwise geometrically and electrostatically unperturbed core region, we quantify and discuss the effects of physical truncation on the structure, relative energy, electrostatics and electronic properties of differently terminated, finite-size models of the NTs. In addition to composition-dependent changes in the valence (VB) and conduction band (CB) edges and resultant band gap (BG), the DFT simulations uncover longitudinal band bending and separation in the finite AlSi and AlGe models. Depending on the given termination of the NTs, such longitudinal effects manifest in conjunction with the radial band separation typical of fully periodic AlSi and AlGe NTs. The strong composition dependence of the longitudinal and radial band bending in AlSi and AlGe NTs suggests different mechanisms for the generation, relaxation and separation of photo-generated holes in AlSi and AlGe NTs, inviting further research in the untapped potential of imogolite compositional and structural flexibility for photo-catalytic applications.

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Role of initial precursors on the liquid-crystalline phase behavior of synthetic aluminogermanate imogolite nanotubes

Cited by 22 publications

References 82 publications

Continuous Binder-Free Fibers of Pure Imogolite Nanotubes

Continuous Binder-Free Fibers of Pure Imogolite Nanotubes

Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Termination Effects in Aluminosilicate and Aluminogermanate Imogolite Nanotubes: A Density Functional Theory Study

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