Publications

Spreading of complex fluids with a soft blade, Marion Krapez, Anaïs Gauthier, Jean-Baptiste Boitte, Odile Aubrun, Jean-François Joanny and Annie Colin, Physical Review Fluids, 7, 084002 (2022)

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.7.084002

Résumé :

The spreading of complex fluids is not only a part of our everyday life but also a
central process in industry to produce functional thin films or protective coatings. Here
we consider the spreading of polymer solutions with an elastic blade that deforms during
the coating (similarly to a brush or a finger). By using complex fluids with well-chosen
rheological properties, we disentangle the effects of shear viscosity, shear thinning, and
normal stresses. We reveal two counterintuitive results : First, the mechanical work needed
to spread a given volume of a shear-thinning fluid is higher than for the same volume of an
equivalent Newtonian fluid at constant spreading velocity. Second, the first normal stress
difference, which usually leads to remarkable behaviors such as the swelling of jets or the
rise of the fluid on a rotating rod, has strikingly negligible effect here.

(a) Schematic representation of the soft blade coating experiment. (b) Map of the central part of the film for xanthane 0.9% during the spreading, as a function of the width z and time t. The color code varies from e = 0 (red) up to e = 250 μm (yellow). The first peak is an artifact and is not taken into consideration. The white line shows the mean thickness e(t) over the film width as a function of time. (c) Evolution of the fluid thickness e with the wetting length lw for two shear-thinning fluids (xanthan 0.9% in blue, HPAM 0.3% in green, and HPAM 0.1% in light green) and a Newtonian fluid (silicone oil, η=480 mPa s in red). The markers correspond to the experimental data measured for different initial fluid volumes. The continuous lines show the scaling law with prefactors 0.17 (for silicone oil) and 0.06 (for xanthan and HPAM) corresponding to the best fits. The dashed lines are the numerical solutions. (d) Comparison of xanthan 0.9% and HPAM 0.5% (dark green). Xanthan is purely shear-thinning while HPAM also generates normal forces at high shear rate. The blue symbols correspond to the same experiments in (c) and (d).

New membrane and electrode assembly concept to improve salinity energy harvesting, Youcef Brahmi and Annie Colin, Soft Matter, (2022)

https://www.sciencedirect.com/science/article/pii/S0196890422000930

Résumé :

The recovery of energy generated from the mixing of fresh and salt water is a new form of renewable energy. However, current processes for energy harvesting from salt gradients remain inefficient mainly because commercial selective membranes have low performances. Hopes for non-selective membranes with nanofluidic channels which have been designed to lower the internal resistance of the cell seem to be in vain. We present a new combination of reverse electrodialysis and capacitive double layer expansion for salinity gradient energy harvesting. Our originality consists in the use of a single selective membrane and two capacitive layers that adsorb ions. The assembly of these elements allows us to double the potential of the open circuit of the cell and thus to multiply by 4 the potentially recoverable power. We present a complete study of a device of a few square centimeters. Contrary to what is generally done, we directly measure the energy and power recovered from the salt gradients in a load resistor. We measure a net power of 2 W.m−2 which is twice the best results presented in the literature to date. Our device makes the principle of energy recovery from salt gradients economically viable.

Can unmixed complex forming polymer surfactant formulations be injected into oil reservoirs or aquifers without clogging them ?, Massinissa Hamouma, Aline Delbos, Christine Dalmazzoneb and Annie Colin, Soft Matter, (2021)

https://pubs.rsc.org/en/content/articlelanding/2021/sm/d1sm00252j#!divAbstract

Résumé :

In the context of enhanced oil recovery or soil remediation, we study the role of interactions between polymers and surfactants on the injectivity of formulations containing mixtures of polymers and surfactants. We show that contrary to the first intuition, the formation of aggregates in polymers surfactants formulations is not necessarily a hindrance to the injection of these formulations into pores. It is important above all to compare the size of aggregates according to the applied shear rate and the pore size to find the formulations that may induce clogging. We highlight a new positive and unexpected phenomenon. The small aggregates that do not lead to clogging ensure the transport of the surfactant vesicles in the porous medium and limit the adsorption of the latter.

Polymeric Foam Pressure-sensing Pens for Measuring Written Language Production
Rigoli CM, Pruvost M, Colin A, Wittenberg E
Preprint from Research Square, 01 Jun 2021

https://europepmc.org/article/ppr/ppr350900

Résumé :

To understand human cognition, cognitive and behavioral scientists measure external behavior using a variety of tools. However, many of these tools are not sensitive enough to detect small changes in behavior, they are too costly, or they can only be used in dedicated lab space, thus limiting behavioral science from studying many populations. Here, we present a reliable, robust, cost-effective device that can measure small modulations in human handwriting behavior through pressure sensing on the writing instrument itself. This is made possible through a cross-disciplinary approach, combining advantages of new, high-sensitivity pressure sensors and experimental psycholinguistics. We show that this instrument is reliable and sensitive to the typical pressure range in writing. Then, we present a proof of concept from an experimental replication and demonstrate the utility of handwriting pressure measurement in a classic experimental paradigm, thus opening new research directions in psycholinguistics, cognitive science, and psychology.

– A new pressure sensor array for local normal stress measurement in complex fluids, Journal of Rheology 65, 583 (2021) ;
Gauthier Anaïs, Pruvost Mickaël, Gamache Olivier, Colin Annie,

https://doi.org/10.1122/8.0000249

Résumé :
A new pressure sensor array, positioned on the bottom plate of a standard torsional rheometer is presented. It is built from a unique piezo-capacitive polymeric foam, and consists of twenty-five capacitive pressure sensors (of surface 4.5×4.5 mm2 each) built together in a 5×5 regular array. The sensor array is used to obtain a local mapping of the normal stresses in complex fluids, which dramatically extends the capability of the rheometer. We demonstrate this with three examples. First, the pressure profile is reconstructed in a polymer solution, which enable the simultaneous measurement of the first and the second normal stress differences N1 and N2, with a precision of 2 Pa. In a second part, we show that negative normal stresses can also be detected. Finally, we focus on the normal stress fluctuations that extend both spatially and temporally ina shear-thickening suspension of cornstarch particles. We evidence the presence of local a unique heterogeneity rotating very regularly. In addition to their low-cost and high versatility, the sensors show here their potential to finely characterize the normal stresses in viscosimetric flows.

A new pressure sensor array for local normal stress measurement in complex fluids, preprint, 2020, https://arxiv.org/abs/2010.04474

Withdrawal and dip coating of an object from a yield-stress reservoir, Wilbert J. Smit, Christophe Kusina, Annie Colin, and Jean-François Joanny Phys. Rev. Fluids 6, 063302 (2021)

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.6.063302

Résumé :

The dip-coating process consists of withdrawing immersed objects from a liquid reservoir. After withdrawal, a significant layer of liquid remains on the object. Various industrial processes (food and beverage industry, automotive industry) use this technique to coat or treat surfaces. Recent studies have shown that the thickness of deposit is determined by the flow inside the reservoir for yield-stress fluids. This is different from the behavior of simple liquids for which the coating thickness is solely determined by the flow inside the meniscus. In this work, we reexamine this question and propose a complete phase diagram linking the Newtonian case and the yield-stress fluid case. We provide asymptotic scaling laws for extreme cases. A good agreement with experiments is obtained.

Aging of cornstarch particles suspended in aqueous solvents at room temperature, Christophe Kusina, Wilbert J. Smit, Jean-Baptiste Boitte, Odile Aubrun, and Annie Colin Phys. Rev. E 103, 052609 (2021)

https://journals.aps.org/pre/pdf/10.1103/PhysRevE.103.052609

Résumé :

Starch suspensions are often used as model systems to demonstrate extreme shear-thickening effects. We studythe aging of cornstarch particles in aqueous suspensions at room temperature by granulometry and rheologicalmeasurements. When starch is diluted in glycerol, no long-term changes are observed. The situation differswhen water is used as solvent. For volume fractions up to 20 vol %, when the cornstarch suspensions in waterare stored under continual agitation, we observe an increase in viscosity. When the cornstarch suspension isaged under quiescent conditions, no evolution of the particle size is observed. In the concentrated situation, therheological properties vary independent of the storage condition. We show that the increase in viscosity is relatedto air trapped in the pore space and to the swelling of the granules and leakage of the amylopectin componentof the starch into the surrounding water. The relative importance of the two processes depends upon the particleconcentration and upon the energy brought to the system.

Polymer Surfactant Interactions in Oil Enhanced Recovery Processes, Massinissa Hamouma, Aline Delbos, Christine Dalmazzone, and Annie Colin, Energy Fuels (2021).

https://pubs.acs.org/doi/10.1021/acs.energyfuels.1c00562?ref=pdf

Résumé :

A soil decontamination or enhanced oil recovery procedure typically requires the injection of a surfactant solution to reduce interfacial tension and promote oil recovery at the pore level, followed by the injection of a polymer solution to avoid the creation of preferential pathways and perform a homogeneous sweep of the reservoir. It is well known that polymers and surfactants interact with each other to form aggregates if they are of opposite charge or due to depletion interactions. To date, it is recommended to use polymers and surfactants that do not interact with each other to avoid clogging the wells. We show here that this precaution is not necessary and that in some cases, the use of interacting polymer and surfactant systems can even be an advantage for oil recovery. Contrary to previous studies, we injected previously mixed and homogeneous formulations into the porous medium and not a sequence of surfactant and polymer plugs. In addition to a total recovery of the oil in place, this strategy allows to limit the adsorption of the surfactant in the pore.

Effect of electrolyte fow on a gas evolution electrode, Soufiane Abdelghani-Idrissi, Nicolas Dubouis, Alexis Grimaud, Philippe Stevens, Gwenaëlle Toussaint & Annie Colin, Scientific Reports volume 11, Article number : 4677 (2021)

https://www.nature.com/articles/s41598-021-84084-1

Résumé :

In this study, the effect of flow of the electrolyte on an electrolysis cell and a zinc cell is investigated. The gain of energy brought by the flow is discussed and compared to the viscous losses in the cells. We point out that the balance between the gained electrical power and the viscous loss power is positive only if the hydrodynamic resistance of the circuit is correctly designed and further comment on the economical viability of the whole process. A model of the studied phenomena is proposed in the last section. This analytical model captures the dynamics of the process, gives the optimal flowing conditions and the limits of the energetical rentability of the process. This study shows that the use of flowing electrolyte in zinc–air batteries can be energetically profitable with the appropriate flowing conditions.

– Impact of the Wetting Length on Flexible Blade Spreading
Marion Krapez, Anaïs Gauthier, Hamid Kellay, Jean-Baptiste Boitte, Odile Aubrun, Jean-François Joanny, and Annie Colin
Phys. Rev. Lett. 125, 254506 – Published 18 December 2020
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.254506

Résumé :

We study the spreading of a Newtonian fluid by a deformable blade, a common industrial problem, characteristic of elastohydrodynamic situations. Here, we consider the case of a finite reservoir of liquid, emptying as the liquid is spread. We evidence the role of a central variable : the wetting length l_w, which sets a boundary between the wet and dry parts of the blade. We show that the deposited film thickness e depends quadratically with l_w. We study this problem experimentally and numerically by integration of the elastohydrodynamic equations, and finally propose a scaling law model to explain how l_w influences the spreading dynamics.

Impact of the Wetting Length on Flexible Blade Spreading, PRL, 2020. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.254506

– Shear thickening in dense non-Brownian suspensions : Viscous to inertial transition,Y. Madraki, A. Oakley, A. Nguyen Le, A. Colin, G. Ovarlez, and S. Hormozi, Journal of Rheology 64, 227 (2020)
https://doi.org/10.1122/1.5129680

Résumé :

We present an experimental study on the viscous to inertial mode of shear thickening in dense non-Brownian suspensions. We design a model suspension consisting of monosized spherical particles within a Newtonian suspending fluid. We develop a protocol for the rheological characterization of dense suspensions using the conventional rheometry technique. Our results provide constitutive laws for suspensions with solid volume fractions close to jamming when both viscous and inertial effects at the particle scale are present. We perform atomic force microscopy to measure forces between the particles immersed in the suspending fluid and show that our system of study corresponds to the frictionless regime of dense suspensions in which viscous and collisional forces dissipate the energy. Finally, we show that the proposed empirical constitutive laws, when approaching jamming, predict the dynamics of dense suspensions in a transient boundary driven flow.

– Density waves in shear-thickening suspensions BY GUILLAUME OVARLEZ, ANH VU NGUYEN LE, WILBERT J. SMIT, ABDOULAYE FALL, ROMAIN MARI, GUILLAUME CHATTÉ, ANNIE COLIN, SCIENCE ADVANCES17 APR 2020 : EAAY5589
https://advances.sciencemag.org/content/6/16/eaay5589.abstract

Résumé :

Shear thickening corresponds to an increase of the viscosity as a function of the shear rate. It is observed in many concentrated suspensions in nature and industry : water or oil saturated sediments, crystal-bearing magma, fresh concrete, silica suspensions, and cornstarch mixtures. Here, we reveal how shear-thickening suspensions flow, shedding light onto as yet non-understood complex dynamics reported in the literature. When shear thickening is important, we show the existence of density fluctuations that appear as periodic waves moving in the direction of flow and breaking azimuthal symmetry. They come with strong normal stress fluctuations of the same periodicity. The flow includes small areas of normal stresses of the order of tens of kilopascals and areas of normal stresses of the order of hundreds of pascals. These stress inhomogeneities could play an important role in the damage caused by thickening fluids in the industry.

– Density waves in shear-thickening suspensions BY GUILLAUME OVARLEZ, ANH VU NGUYEN LE, WILBERT J. SMIT, ABDOULAYE FALL, ROMAIN MARI, GUILLAUME CHATTÉ, ANNIE COLIN, SCIENCE ADVANCES17 APR 2020 : EAAY5589

https://advances.sciencemag.org/content/6/16/eaay5589

Résumé :

Shear thickening corresponds to an increase of the viscosity as a function of the shear rate. It is observed in many concentrated suspensions in nature and industry : water or oil saturated sediments, crystal-bearing magma, fresh concrete, silica suspensions, and cornstarch mixtures. Here, we reveal how shear-thickening suspensions flow, shedding light onto as yet non-understood complex dynamics reported in the literature. When shear thickening is important, we show the existence of density fluctuations that appear as periodic waves moving in the direction of flow and breaking azimuthal symmetry. They come with strong normal stress fluctuations of the same periodicity. The flow includes small areas of normal stresses of the order of tens of kilopascals and areas of normal stresses of the order of hundreds of pascals. These stress inhomogeneities could play an important role in the damage caused by thickening fluids in the industry.

– Pruvost, M., Smit, W.J., Monteux, C. et al. Integration of a soft dielectric composite into a cantilever beam for mechanical energy harvesting, comparison between capacitive and triboelectric transducers. Sci Rep 10, 20681 (2020). https://doi.org/10.1038/s41598-020-77581-2

Integration of a soft dielectric composite into a cantilever beam for mechanical energy harvesting, comparison between capacitive and triboelectric transducers. Sci Rep 10, 20681 (2020) https://doi.org/10.1038/s41598-020-77581-2

Résumé :

Flexible dielectrics that harvest mechanical energy via electrostatic effects are excellent candidates as power sources for wearable electronics or autonomous sensors. The integration of a soft dielectric composite (polydimethylsiloxane PDMS-carbon black CB) into two mechanical energy harvesters is here presented. Both are based on a similar cantilever beam but work on different harvesting principles : variable capacitor and triboelectricity. We show that without an external bias the triboelectric beam harvests a net density power of 0.3 μW/cm2 under a sinusoidal acceleration of 3.9g at 40 Hz. In a variable capacitor configuration, a bias of 0.15 V/μm is required to get the same energy harvesting performance under the same working conditions. As variable capacitors’ harvesting performance are quadratically dependent on the applied bias, increasing the bias allows the system to harvest energy much more efficiently than the triboelectric one. The present results make CB/PDMS composites promising for autonomous portable multifunctional systems and intelligent sensors.

– Stress Field inside the Bath Determines Dip Coating with Yield-Stress Fluids in Cylindrical Geometry, Wilbert J. Smit, Christophe Kusina, Jean-François Joanny, and Annie Colin. Phys. Rev. Lett. 123, 148002 – Published 30 September 2019

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.148002

Résumé :

We study experimentally and theoretically the thickness of the coating obtained by pulling out a rod from a reservoir of yield-stress fluid. Opposite to Newtonian fluids, the coating thickness for a fluid of large enough yield stress is determined solely by the flow inside the reservoir and not by the flow inside the meniscus. The stress field inside the reservoir determines the thickness of the coating layer. The thickness is observed to increase nonlinearly with the sizes of the rod and of the reservoir. We develop a theoretical framework that describes this behavior and allows us to precisely predict the coating thickness.

– Chasing Aqueous Biphasic Systems from Simple Salts by exploring the LiTFSI/LiCl/H2O Phase Diagram, Nicolas Dubouis, Chanbum Park, Michaël Deschamps, Soufiane Abdelghani-Idrissi, Matej Kanduč, Annie Colin, Mathieu Salanne, Joachim Dzubiella, Alexis Grimaud, and Benjamin Rotenberg, ACS Cent. Sci. 2019, 5, 4, 640–643

https://pubs.acs.org/doi/10.1021/acscentsci.8b00955

Résumé :

Aqueous biphasic systems (ABSs), in which two aqueous phases with different compositions coexist as separate liquids, were first reported more than a century ago with polymer solutions. Recent observations of ABS forming from concentrated mixtures of inorganic salts and ionic liquids raise the fundamental question of how “different” the components of such mixtures should be for a liquid–liquid phase separation to occur. Here we show that even two monovalent salts sharing a common cation (lithium) but with different anions, namely, LiCl and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), may result in the formation of ABSs over a wide range of compositions at room temperature. Using a combination of experimental techniques and molecular simulations, we analyze the coexistence diagram and the mechanism driving the phase separation, arising from the different anion sizes. The understanding and control of ABS may provide new avenues for aqueous-based battery systems.

– Polymeric foams for flexible and highly sensitive low-pressure capacitive sensors. Pruvost, M., Smit, W.J., Monteux, C. et al. npj Flex Electron 3, 7 (2019). https://doi.org/10.1038/s41528-019-0052-6

Résumé :
Flexible low-pressure sensors ( <10 kPa) are required in areas as diverse as blood-pressure monitoring, human–computer interactions, robotics, and object detection. For applications, it is essential that these sensors combine flexibility, high sensitivity, robustness, and low production costs. Previous works involve surface micro-patterning, electronic amplification (OFET), and hydrogels. However, these solutions are limited as they involve complex processes, large bias voltages, large energy consumption, or are sensitive to evaporation. Here, we report a major advance to solve the challenge of scalable, efficient and robust e-skin. We present an unconventional capacitive sensor based on composite foam materials filled with conductive carbon black particles. Owing to the elastic buckling of the foam pores, the sensitivity exceeds 35 kPa−1 for pressure <0.2 kPa. These performances are one order of magnitude higher than the ones previously reported. These materials are low-cost, easy to prepare, and display high capacitance values, which are easy to measure using low-cost electronics. These materials pave the road for the implementation of e-skin in commercialized applications.

Highly sensitive material for blood pressure sensor, npj Flex Electron 3, 7 (2019). https://doi.org/10.1038/s41528-019-0052-6

– Microporous electrostrictive materials for vibrational energy harvesting, M Pruvost, WJ Smit, C Monteux, P Poulin, A Colin - Multifunctional Materials, 2018, https://doi.org/10.1088/2399-7532/aab2ff

Résumé :
We present electrostrictive materials with excellent properties for vibrational energy harvesting applications. The developed materials consist of a porous carbon black composite, which is processed using water-in-oil emulsions. In combination with an insulating layer, the investigated structures exhibit a high effective relative dielectric permittivity (up to 182 at 100 Hz) with very low effective conductivity (down to 2.53 10−8 S m−1). They can generate electrical energy in response to mechanical vibrations with a power density of 0.38 W m−3 under an applied bias electric field of 32 V. They display figures or merit for energy harvesting applications well above reference polymer materials in the field, including fluorinated co- and ter-polymers synthetized by heavy chemical processes. The production process of the present materials is based on non hazardous and low-cost chemicals. The soft dielectric materials are highly flexible (Young’s modulus of 1 MPa) making them also suited for highly sensitive capacitive sensors.

– Giant electrostrictive response and piezoresistivity of emulsion templated nanocomposites. A Luna, M Pruvost, J Yuan, C Zakri, W Neri, C Monteux, P Poulin, A Colin, Langmuir 33 (18), 4528-4536, (2017) https://doi.org/10.1021/acs.langmuir.6b04185

Résumé :
Using an emulsion road and optimizing the dispersion process, we prepare polymer carbone nanotubes (CNT) and polymer reduced graphene oxide (rGO) composites. The introduction of conductive nanoparticles into polymer matrices modifies the electronic properties of the material. We show that these materials exhibit giant electrostriction coefficients in the intermediate filler concentration (below 1 wt %). This makes them very promising for applications such as capacitive sensors and actuators. In addition, the values of the piezoresistivity measured in the high filler concentration situation are at least an order of magnitude greater than the one reported in the literature. This opens the way to use these materials for stress or strain sensor applications considering their giant responses to mechanical deformations. Giant electrostrictive response and piezoresistivity of emulsion templated nanocomposites. https://doi.org/10.1021/acs.langmuir.6b04185