ANR project ANR-17-CE04-0003: For WATER Quality Monitoring – 4WATER

The water crisis is the #1 global risk based on impact to society as announced by the World Economic Forum in January 2015 [1]. Indeed, groundwater is a scarce resource as it only account for 0.3% of the Earth’s total freshwater reserves. And already, 663 million people – 1 in 10 – lack access to safe water and 2.4 billion people – 1 in 3 – lack access to adequate sanitation (including 1/3 of all schools)[2,3] which has been shown to strongly impact local water quality and population’s health [4] Even when safe water is accessible, there can be great variability in its composition depending on many environmental and human factors [5], which can sporadically render it unsafe. Despite this, little is known of this variabilities and interplays because no global and permanent monitoring of these freshwater resources. Hence the objective of this proposalto develop a new low cost, multi-analyte water quality monitoring solution.

See a video description of the project.

1. World Economic Forum. (2015). Global Risks 2015 Report.
2. World Health Organization and UNICEF Joint Monitoring Programme (JMP). (2015) Progress on Drinking Water and Sanitation, 2015 Update and MDG Assessment.
3. United States Census Bureau Estimates. (2015). United States and World Population Clock.
4. Contribution of Water Pollution From Inadequate Sanitation and Housing Quality to Diarrheal Disease in Low-Cost Housing Settlements of Cape Town, South Africa. Thashlin Govender, Jo M. Barnes, Clarissa H. Pieper, Am J Public Health. 2011 July; 101(7): e4–e9.
5. Spatial and Seasonal Variability in the Water Quality Characteristics of an Ephemeral Wetland. Chad J. Boeckman and Joseph R. Bidwell Proc. Okla. Acad. Sci. 87: pp 45-54 (2007)

The project is coordinated by Jean-Christophe P. Gabriel, Nanoscience Research Director at CEA/NIMBE (Nanosciences et innovation pour les matériaux, la biomédecine et l’énergie), with the following partners:

• Patrick Davidson, LPS Laboratoire de Physique des Solides
• Bérengère Lebental, LPICM Laboratoire de physique des interfaces et des couches minces
• Laurent Michot, Phenix – PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX
• Rachid Mouflih, HEMERA France

The total financial aid received of the ANR was of 655 966 euros
Beginning and duration of the scientific project: December 2017-December 2022 – 60 Months (including prolongations).

Ph. D. Student that worked on this project:

1. Karin El Rifaii (Supervisor: Patrick Davidson); defence on December 21^st, 2021. Manuscript is here.
2. Gookbin Cho (Supervisors: Bérengère Lebental and Gaël Zucchi); defence on December 15^th, 2021. Manuscript is here.
3. Lina Cherni (Supervisor: JCP Gabriel); defence planned in January 26^th, 2023. Manuscript is here

Scientific Production:

Patents:

1) “Method for protecting air-sensitive or evaporation-sensitive objects.” Jean Christophe Gabriel, Monika Spano, Fatima-Ezzahra Hami, WO/2021/089957

=> Available for Licensing

Publications and communications to conferences / workshop / congress

For a list of all publications and communications to conferences linked to this project see here in the open access HAL repository.

Highlights:

1) Isotropic, nematic, and lamellar phases in colloidal suspensions of nanosheets
Davidson, P; Penisson, C; Doru Constantin; Gabriel, JCP
June 26th, 2018, Proceeding of the National Academy of Sciences of the USA, 115(26) 6662-6667 (90+ citations)

Abstract: The phase diagram of colloidal suspensions of electrically charged nanosheets, such as clays, despite their many industrial uses, is not yet understood either experimentally or theoretically. When the nanosheet diameter is very large (similar to 100 nm to 1 µm), it is quite challenging to distinguish the lamellar liquid-crystalline phase from a nematic phase with strong stacking local order, often called “columnar” nematic. We show here that newly upgraded smallangle X-ray scattering beamlines at synchrotron radiation facilities provide high-resolution measurements which allow us to identify both phases unambiguously, provided that single domains can be obtained. We investigated dilute aqueous suspensions of synthetic Sb₃P₂O₁₄^3- nanosheets that self-organize into two distinct liquid-crystalline phases, sometimes coexisting in the same sample. Close examination of their X-ray reflection profiles in the directions perpendicular to the director demonstrates that these two mesophases are a columnar nematic and a lamellar phase. In the latter, the domain size reaches up to similar to 20 µm, which means that each layer is made of > 600 nanosheets. Because the lamellar phase was only rarely predicted in suspensions of charged disks, our results show that these systems should be revisited by theory or simulations. The unexpected stability of the lamellar phase also suggests that the rims and faces of Sb₃P₂O₁₄^3- nanosheets may have different properties, giving them a patchy particle character.

2) Methods for dispersing carbon nanotubes for nanotechnology applications: liquid nanocrystals, suspensions, polyelectrolytes, colloids and organization control.
Sergio Manzetti, Jean-Christophe P. Gabriel, International Nano Letters 9 (1), 31-49 (2019) (90+ citations).

Abstract: Carbon nanotubes (CNTs) are a central part of advanced nanomaterials and are used in state-of-the-art technologies, based on their high tensile strength, excellent thermal transfer properties, low-band gaps and optimal chemical and physical stability. Carbon nanotubes are also intriguing given their unique -electron-rich structures, which opens a variety of possibilities for modifications and alterations of their chemical and electronic properties. In this review, a comprehensive survey of the methods of solubilization of carbon nanotubes is presented, forming the methodological foundation for synthesis and manufacturing of modified nanomaterials. The methods presented herein show that solubilized carbon nanotubes have a great potential in being applied as reactants and components for advanced solar cell technologies, nanochemical compounds in electronics and as parts in thermal transfer management. An example lies in the preservation of the aromatic chemistry in CNTs and ligation of functional groups to their surfaces, which confers CNTs with an optimal potential as tunable Schottky contacts, or as parts in nanotransistors and nano-resistances. Future nanoelectronic circuits and structures can therefore depend more and more on how carbon nanotubes are modified and functionalized, and for this, solubilization is oftena critical part of their fabrication process. This review is important, is in conjecture with the latest developments in synthesis and modification of CNTs, and provides the know-how for developing new CNT-based state-of-the-art technologies, particularly with emphasis on computing, catalysis, environmental remediation as well as microelectronics.

3) Destabilization of the Nematic Phase of Clay Nanosheet Suspensions by Polymer Adsorption
Karin El Rifaii, Henricus H. Wensink, Thomas Bizien, Jean-Christophe P. Gabriel, Laurent Michot, Patrick Davidson, Langmuir 36(42) 12563–12571 (2020)

Abstract: Complex aqueous mixtures comprised of swelling clays and hydrosoluble polymers naturally occur in soils and play a major role in pedogenesis. They are also very often used for formulating oil-well drilling fluids, paints, and personal-care products. The suspensions of some natural clays, thanks to their large nanoparticle aspect ratio, spontaneously form nematic liquidcrystalline phases where the particles align parallel to each other, which affects their flow properties. We observed that adding small amounts of hydrosoluble polymers to these clay suspensions destabilizes the nematic phase with respect to the isotropic (disordered) phase. The polymers that we used (poly(ethylene oxide) and dextran) were too small to adopt particle-bridging conformations and small-angle X-ray scattering experiments showed that the structure of the nematic phase is not altered by polymer doping. However, the adsorption isotherm shows that the macromolecules adsorb onto the clay nanosheets, effectively coating them with a polymer layer. Our extension of Onsager’s theory for polymer-coated platelets properly captures the experimental phase diagram and shows how the nematic phase destabilization can be due to the polymer adsorbing more on the platelet faces than at the rim. Because the flow properties of the nematic phase are very different from those of the isotropic phase, the presence or absence of the former phase is an important factor to be determined and considered to explain the rheological behavior of these complex systems.

4) Fine tuning of the structural colors of photonic nanosheet suspensions by polymer doping
Karin El Rifaii, Henricus H. Wensink, Claire Goldmann, Laurent Michot, Jean-Christophe P. Gabriel, Patrick Davidson, Soft Matter 17(41) 9280-9292 (2021)

Abstract: Aqueous suspensions of nanosheets are readily obtained by exfoliating low-dimensional mineral compounds like H₃Sb₃P₂O₁₄. The nanosheets self-organize, at low concentration, into a periodic stack of membranes, i.e. a lamellar liquid-crystalline phase. Due to the dilution, this stack has a large period of a few hundred nanometres, it behaves as a 1-dimensional photonic material and displays structural colours. We experimentally investigated the dependence of the period on the nanosheet concentration. We theoretically showed that it cannot be explained by the usual DLVO interaction between uniform lamellae but that the particulate nature of nanosheet-laden membranes must be considered. Moreover, we observed that adding small amounts of 100 kDa poly(ethylene oxide) (PEO) decreases the period and allows tuning the colour throughout the visible range. PEO adsorbs on the nanosheets, inducing a strong reduction of the nanosheet charge. This is probably due to the Lewis-base character of the EO units of PEO that become protonated at the low pH of the system, an interpretation supported by theoretical modeling. Oddly enough, adding small amounts of 1 MDa PEO has the opposite effect of increasing the period, suggesting the presence of an additional intermembrane repulsion not yet identified. From an applied perspective, our work shows how the colours of these 1-dimensional photonic materials can easily be tuned not only by varying the nanosheet concentration (which might entail a phase transition) but also by adding PEO. From a theoretical perspective, our approach represents a necessary step towards establishing the phase diagram of aqueous suspensions of charged nanosheets.

5) Gold–clay nanocomposite colloids with liquid-crystalline and plasmonic properties
Karin El Rifaii, Patrick Davidson, Laurent Michot, Cyrille Hamon, Chem. Commun., 2021,57, 10359-10362

Abstract: Imparting liquid-crystal (LC) materials with the plasmonic properties of metal nanoparticles is actively pursued for applications. We achieved this goal by synthetizing gold nanoparticles onto clay nanosheets, leading to nematic nanocomposite suspensions. Optical observations and structural analysis show the growth of the gold nanoparticles without altering the LC properties of the nanosheets. These colloids display plasmonic structural colours and they can be aligned by an electric field, which is relevant for fundamental and materials chemistry of colloidal LC.

6) « Do aqueous suspensions of smectite clays form a smectic liquid-crystalline phase? » Karin El Rifaii, Henricus H. Wensink, Florian Puchtler, Ivan Dozov, Thomas Bizien, Laurent J. Michot, Jean-Christophe P. Gabriel, Josef Breu, Patrick Davidson, Langmuir, 38(48) 14563-14573 (2022).

Abstract: Bottom-up strategies for the production of well-defined nanostructures often rely on the self-assembly of anisotropic colloidal particles (nanowires and nanosheets). These building blocks can be obtained by delamination in a solvent of low-dimensionality crystallites. To optimize particle availability, determination of the delamination mechanism and the different organization stages of anisotropic particles in dispersion is essential. We address this fundamental issue by exploiting a recently developed system of fluorohectorite smectite clay mineral that delaminates in water, leading to colloidal dispersions of single-layer, very large (≈20 μm) clay sheets at high dilution. We show that when the clay crystallites are dispersed in water, they swell to form periodic one-dimensional stacks of fluorohectorite sheets with very low volume fraction (<1%) and therefore huge (≈100 nm) periods. Using optical microscopy and synchrotron X-ray scattering, we establish that these colloidal stacks bear strong similarities, yet subtle differences, with a smectic liquid-crystalline phase. Despite the high dilution, the colloidal stacks of sheets, called colloidal accordions, are extremely robust mechanically and can persist for years. Moreover, when subjected to AC electric fields, they rotate as solid bodies, which demonstrates their outstanding internal cohesion. Furthermore, our theoretical model captures the dependence of the stacking period on the dispersion concentration and ionic strength and explains, invoking the Donnan effect, why the colloidal accordions are kinetically stable over years and impervious to shear and Brownian motion. Because our model is not system specific, we expect that similar colloidal accordions frequently appear as an intermediate state during the delamination process of two-dimensional crystals in polar solvents.

7) Crystalline restacking of 2D-materials from their nanosheets suspensions.  Lina Cherni, Karin El Rifaii, Henricus H. Wensink,* Sarah M. Chevrier, Claire Goldmann, Laurent J. Michot, Patrick Davidson,* Jean-Christophe P. Gabriel*   Nanoscale 15, 18359-18367 (2023). Part of Nanoscale’s Most Popular 2023 Articles.

Abstract: We report here the highly ordered restacking of the layered phosphatoantimonic dielectric materials H_3(1−x)M_3xSb₃P₂O₁₄, (where M = Li, Na, K, Rb, Cs and 0 ≤ x ≤ 1), from their nanosheets dispersed in colloidal suspension, induced by a simple pH change using alkaline bases. H₃Sb₃P₂O₁₄ aqueous suspensions are some of the rare examples of colloidal suspensions based on 2D materials exhibiting a lamellar liquid crystalline phase. Because the lamellar period can reach several hundred nanometers, the suspensions show vivid structural colors and because these colors are sensitive to various chemicals, the suspensions can be used as sensors. The structures of the lamellar liquid crystalline phase and the restacked phase have been studied by X-ray scattering (small and wide angle), which has followed the dependence of the lamellar/restacked phase equilibrium on the cation exchange rate, x. The X-ray diffraction pattern of the restacked phase is almost identical to that of the M₃Sb₃P₂O₁₄ crystalline phase, showing that the restacking is highly accurate and avoids the turbostratic disorder of the nanosheets classically observed in nanosheet stacking of other 2D materials. Strikingly, the restacking process exhibits features highly reminiscent of a first-order phase transition, with the existence of a phase coexistence region where both ∼1 nm (interlayer spacing of the restacked phase) and ∼120 nm lamellar periods can be observed simultaneously. Furthermore, this first-order phase transition is well described theoretically by incorporating a Lennard-Jones-type lamellar interaction potential into an entropy-based statistical physics model of the lamellar phase of nanosheets. Our work shows that the precise cation exchange produced at room temperature by a classical neutralization reaction using alkaline bases leads to a crystal-like restacking of the exfoliated free Sb₃P₂O₁₄³⁻ nanosheets from suspension, avoiding the turbostratic disorder typical of van der Waals 2D materials, which is detrimental to the controlled deposition of nanosheets into complex integrated electronic, spintronic, photonic or quantum structures.