Samuel Marre | University of Bordeaux (France) (original) (raw)

Papers by Samuel Marre

Langmuir, 2012

Supercritical fluids offer fast and facile routes toward well-crystallized tailor-made cerium oxi... more Supercritical fluids offer fast and facile routes toward well-crystallized tailor-made cerium oxide nanoparticles. However, the use of surfactants to control morphology and surface properties remains essential. Therefore, although water, nearcritical (nc) or supercritical (sc), is a solvent of choice, the poor water solubility of some surfactants could require other solvent systems such as alcohols, which could themselves behave as surface modifiers. In here, the influence of seven different alcohols, MeOH, EtOH, PrOH, iPrOH, ButOH, PentOH, and HexOH, in alcothermal conditions (300°C , 24.5 MPa) over CeO 2 nanocrystals (NCs) size, morphology, and surface properties was investigated. The crystallite size of the CeO 2 nanocrystals can be tuned in the range 3−7 nm depending on the considered alcohol, and their surface has been modified by these solvents without the use of surfactants. Mechanisms are proposed for the interaction of primary and secondary alcohols with CeO 2 surface and its functionalization during the synthesis based on FTIR and TGA-MS studies. This study allows apprehending the role of alcohols during the synthesis and may lead to an informed choice of solvent as a function of the required size and surface properties of CeO 2 NCs. It also opens new route to CeO 2 functionalization using supercritical alcohol derivatives.

The Journal of Supercritical Fluids, 2015

Accessing fluids thermophysical properties is crucial in chemical engineering for they are requir... more Accessing fluids thermophysical properties is crucial in chemical engineering for they are required in most of process parameter calculations. Nevertheless, these are not always available in the literature. In the present paper, we propose a fast and efficient microfluidic approach for simultaneously accessing density and viscosity of homogeneous fluids mixtures. In comparison with classical set-ups, microfluidic devices exhibit higher heat transfer capability and small volumes, resulting in an easy control of temperature, fast conditions screening and improved operation safety. A set-up was designed based on the subtraction of two pressures: capillary and bypass lines. The devices use a capillary system with a diameter of 73.6 m (±0.5%). The proposed set-up can work in a wide range of pressures (10 < P(bar) < 200) and temperatures (30 < T( • C) < 227). The developed strategy was applied to pure fluids (CO 2 and N 2 ), and to mixtures (CYC + CO 2 and CO 2 + H 2 ).

The last few years have seen the development of a new field of investigation, so called ”Supercri... more The last few years have seen the development of a new field of investigation, so called ”Supercritical Microfluidics” with the basic idea to combine the advantages of size reduction provided by microsystems - advanced control of operating parameters, reproducibility, in situ and online characterization, rapid screening, fast mass and heat transfer and low reagent consumption - to the unique properties of supercritical fluids (SCFs) at high pressures and temperatures. This combination can address some of the limitations of both macroscale SCFs reactors and conventional liquid microfluidic reactors. Indeed, while the environmental advantages of SCFs such as carbon dioxide or water are attractive, it is their physicochemical properties that could drive their use several microfluidics applications. In particular the absence of surface tension, favorable transport properties and average densities provide means for solution-based processes in an environment that behaves much like a gas. T...

The application of the ICMCB process of nanostructured and nano-materials synthesis by chemical t... more The application of the ICMCB process of nanostructured and nano-materials synthesis by chemical transformation in s upercritical fluids is applied to the modification of particle surface. On the one hand, the surface modification can be controlled by organic molecules as in the case of the synthesis of functionalise d palladium nanoparticles (7 nm). The organic molecules stabilise the nanoparticles against

Journal of Physical Chemistry B, 2009

The CO(2) sorption and polymer swelling of hydroxytelechelic polybutadiene (HTPB) and poly(ethyle... more The CO(2) sorption and polymer swelling of hydroxytelechelic polybutadiene (HTPB) and poly(ethylene glycol) (PEG) have been investigated as a function of temperature and CO(2) pressure by combining in situ near-infrared spectroscopy with molecular modeling. The results reported here for the PEG-CO(2) system are in a very good agreement with literature data hence validating our experimental procedure. It has been found that CO(2) sorption and swelling effect is more important for PEG than for HTPB. For both polymers, an increase of temperature leads to a strong decrease of both the CO(2) sorption and swelling. In order to identify at a molecular level the nature and strength of intermolecular interaction occurring between CO(2) and the polymers, ab initio calculations have been performed on model structures, representative of the main functional group of the polymer, and their complex with CO(2). Trans-3-hexene (3-Hex), propyl methyl ether (PME) and methoxytrimethylsilane (MTMS) have been selected to mimic the functional groups of HTPB, PEG and polydimethyl siloxane (PDMS), respectively. The last system has been chosen since previous works on the swelling of PDMS by high pressure CO(2) have revealed the high ability of CO(2) to swell both uncrosslinked and crosslinked PDMS. The calculated stabilization energies of the MTMS-CO(2), PME-CO(2), and 3-Hex-CO(2) dimers indicate that CO(2) interacts specifically with the three moieties through a Lewis acid-Lewis base type of interaction with the energies displaying the following order: E(MTMS-CO(2)) = -3.59 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; E(PME-CO(2)) = -3.43 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; E(3-Hex-CO(2)) = -2.5 kcal/mol. Since the solubility of CO(2) in the corresponding homopolymers follows the same order, it is evidenced that the stronger the interaction between CO(2) and the polymer, the higher the CO(2) sorption. Therefore, even if one cannot exclude the influence of free volume and chain flexibility of the polymer, it appears that the solubility of CO(2) in the polymer is predominantly governed by the interaction between CO(2) and the polymer. Although the same trend is observed for the swelling of the polymer as a function of the CO(2) pressure, we have found that for a given value of CO(2) sorption, the swelling of the polymer depends on its nature, meaning that the swelling is not only governed by the CO(2)-polymer interaction but also by other intrinsic properties of the polymer.

Applied Physics Letters, 2009

Dripping to jetting transition from liquid-liquid to liquid-gas systems has been widely studied i... more Dripping to jetting transition from liquid-liquid to liquid-gas systems has been widely studied in microfluidics. Recent developments have permitted the use of supercritical fluids at high pressure and various temperatures in microfluidic systems to develop sustainable processes. In this article, we use this strategy to demonstrate the possibility to generate stable droplets and reversible dripping to jetting transitions at microscale

ChemPhysChem, 2015

CeO2 nanocrystals (NCs) have attracted increasing interest over the past few years, in particular... more CeO2 nanocrystals (NCs) have attracted increasing interest over the past few years, in particular for their use in catalysis reactions. Near- and supercritical alcohols mediated syntheses have been proved to be innovative ways to obtain CeO2 NCs with controlled crystallite sizes (from 3 to 8 nm depending on the alcohol) and surface functionalities, with alcohols moieties. When submitted to a thermal treatment at 500 °C - required to desorb/degradate surface organic species - these powders displayed different behaviors depending on the alcohol used during the synthesis. Cerium oxide powders synthesized in scMeOH, scEtOH and sciPrOH undergo sintering during the treatment at 500 °C, with a decrease of their specific surface area. Oppositely, those synthesized in scButOH, ncPentOH and ncHexOH keep their initial crystallite sizes and morphology but witness a great enhancement of their specific surface area (up to 200 m².g-1), which is unprecedented after such thermal treatment.

Under supercritical conditions (i.e. when the temperature and the pressure of a substance are abo... more Under supercritical conditions (i.e. when the temperature and the pressure of a substance are above its thermodynamic critical point), water becomes a fluid with unique properties that can be used to treat a wide variety of wastes. For example, during Supercritical Water Oxidation (SCWO) organic wastes can be almost fully converted into carbon dioxide and water. Already used in a variety of terrestrial applications (for example onboard ships), SCWO technology, because of its potential for extremely high waste conversion efficiencies, is of great interest in the context of space exploration programs. A SCWO reactor could be used in the treatment of a number of waste streams typically found onboard spacecraft used in long duration missions or as a part of the Environmental Control and Life Support (ECLS) system for an extraterrestrial habitat. As part of the DECLIC program, the first two investigation phases motivated by the potential of future SCWO applications in microgravity have e...

Lab on a Chip, 2014

In this work, we present a novel microfluidic-based approach for investigating the thermodynamics... more In this work, we present a novel microfluidic-based approach for investigating the thermodynamics of multicomponent systems at high pressures and temperatures, such as determining miscibility diagrams and critical coordinates of complex mixtures. The developed method is primarily based on (i) bubble and dew point detection through optical characterization and (ii) the use of a so-called dynamic stop-flow measurement mode for fast screening of the diagram parameters, mainly P, T and composition. Our strategy was validated through the studies of model binary CO 2 -alkane mixtures. The obtained results were then compared to PREOS-calculated and literature data. We later applied this strategy for determining ternary and quaternary mixtures critical coordinates. This approach has equal accuracy compared to conventional high-pressure optical cell methods but allows for a much faster phase diagram determination, taking advantage of improved heat and mass transfers on the microscale and of the dynamic stop-flow approach. ; Fax: +0033 5 40 00 27 61; Tel: +0033 5 40 00 26 72 † Electronic supplementary information (ESI) available. See

The Journal of Physical Chemistry C, 2009

The formation of surface nanostructures allows assemblies of materials at different scales, openi... more The formation of surface nanostructures allows assemblies of materials at different scales, opening new routes toward the design of advanced nanostructured materials. The decoration of surfaces with shape-and sizecontrolled metal nanoparticles can be achieved through the reduction of hexafluoroacetylacetonate complexes [M(hfac) x ] with H 2 in supercritical CO 2 /alcohol at low temperature with neither catalyst nor surface prefunctionalization. This paper investigates the influence of different alcohols, methanol, ethanol, and isopropanol, used as cosolvent on the reduction kinetics of Cu(hfac) 2 · H 2 0 in the supercritical CO 2 /alcohol/H 2 mixtures. The results are applied to the modeling of the decoration process of silica spheres, used as a model substrate, with copper nanoparticles (5-17 nm). The model, using the decomposition kinetics of the precursor, is based on a bimodal process: (i) an initial homogeneous nucleation in the supercritical media and (ii) a fast heterogeneous growth by coalescence on the surface of the silica particles. We demonstrate good agreements between the simulated results and the experimental data showing an advanced kinetically controlled size of the supported nanoparticles in the range of temperature 100-125°C and residence time 0-120 min.

Nanotechnology, 2006

Recent developments in multifunctional devices show the interest in combining different materials... more Recent developments in multifunctional devices show the interest in combining different materials to obtain specific properties. Through supercritical fluid chemical deposition (SFCD), silica spheres, used as a model support, were coated with copper nanoparticles (5-17 nm) with a tuneable amount of coverage (40-80%). The coating process is based on the reduction of metal precursors with hydrogen in a supercritical CO 2 /isopropanol mixture in a temperature range between 100 and 150 • C at 24 MPa. Several parameters were studied such as temperature, residence time or mass ratio of precursor/silica spheres, allowing control of the size of the copper nanoparticles and of the amount of coverage from metal nanoparticles scattered onto the surface to a metal nanoparticle thin film.

Langmuir, 2011

We describe fluoropolymer modification of silicon microreactors for control of wetting properties... more We describe fluoropolymer modification of silicon microreactors for control of wetting properties in chemical synthesis applications and characterize the impact of the coating on liquidÀliquid multiphase flows of solvents and water. Annular flow of nitrogen gas and a Teflon AF (DuPont) dispersion enable controlled evaporation of fluoropolymer solvent, which in turn brings about three-dimensional polymer deposition on microchannel walls. Consequently, the wetting behavior is switched from hydrophilic to hydrophobic. Analysis of microreactors reveals that the polymer layer thickness increases down the length of the reactor from ∼1 to ∼13 μm with an average thickness of ∼7 μm. Similarly, we show that microreactor surfaces can be modified with poly(tetrafluoroethylene) (PTFE). These PTFE-coated microreactors are further characterized by measuring residence time distributions in segmented liquidÀliquid multiphase flows, which display reduced axial dispersion for the coated microreactors. Applying particle image velocimetry, changes in segment shape and velocity fluctuations are observed resulting in reduced axial dispersion. Furthermore, the segment size distribution is narrowed for the hydrophobic microreactors, enabling further control of residence distributions for synthesis and screening applications.

Langmuir, 2008

Controlling the surface characteristics of inorganic materials with an organic shell is of great ... more Controlling the surface characteristics of inorganic materials with an organic shell is of great interest for control of the properties of the final material. A challenge is thus to be able to deposit a polymer shell with different solvation properties onto the surface of inorganic particles and to have a good control of the thickness of the organic layer without a prefunctionalization of surfaces. We demonstrate, in this paper, a method for coating silica particles (170-550 nm), used as model substrates, with either a hydrophilic (polyethylene glycol) or a hydrophobic polymer (polybutadiene hydroxy terminated) using a supercritical antisolvent process (precipitation from a compressed antisolvent). Several operating parameters were studied to control precisely the thickness of the deposited layer (from 2 to 30 nm), which was characterized using TEM, FESEM, XPS, and UV-visible techniques. This work demonstrates that supercritical antisolvent processes are powerful methods and good alternatives to conventional coating techniques toward the development of hybrid and/or core-shell nanomaterials.

Journal of the Association for Laboratory Automation, 2009

C hemically synthesized nanomaterials, such as nanocrystalline quantum dots, are being considered... more C hemically synthesized nanomaterials, such as nanocrystalline quantum dots, are being considered as the active element in many applications, including photovoltaics, displays, and biochem sensing. To realize the promise of these devices, it will be critical to have an efficient, reproducible synthesis technique of the nanostructures. Currently, nanoparticles are synthesized in a batch mode in small volumes, which is appropriate for studying the fundamental properties of nanosized structures and for developing proof of principle device structures. However, batch synthesis suffers from control of size, size distribution, and quality of the nanomaterial from batch to batch. Moreover, there is an inherent difficulty in scaling up to quantities more reasonable for device development and optimization. Continuous-flow reactors based on microfluidics (microreactors) integrated with heaters and fluid control elements offer a solution to these problems and additional advantages. We describe continuous synthesis of nanostructures in microfluidic systems consisting of multiple subemillimeter-sized channels in which fluid flows continuously and chemical reactions take place. The small reaction volumes combined with the high heat and mass transfer rates enable reactions to be performed under more controlled conditions with higher yields than can typically be achieved with conventional reactors. Moreover, manipulation of reaction parameters, while the reaction proceeds, allows

The Journal of Supercritical Fluids, 2012

Working under supercritical conditions at microscale combines the advantages of size reduction pr... more Working under supercritical conditions at microscale combines the advantages of size reduction provided by microsystems to the unique properties of supercritical fluids (SCFs). The so-called "supercritical microfluidics" therefore addresses the limitations of both macroscale SCFs reactors and conventional liquid microfluidic reactors. In this review, we present recent developments in supercritical microfluidics processes with the design of microreactors capable of working under pressure and temperature, some general characteristics of supercritical microflows and, through selected examples, flow-through chemistry and nanocrystals synthesis in supercritical microreactors.

The Journal of Supercritical Fluids, 2010

Mixing catalyst NPs with magnesium was proved to be an efficient way to improve the sorption kine... more Mixing catalyst NPs with magnesium was proved to be an efficient way to improve the sorption kinetics of hydrogen. Recently, as an alternative to conventional ball milling process, we have reported the interest of using the supercritical fluid chemical deposition process to deposit catalyst metal NPs on the surface of Mg crystals in order to improve significantly the material cyclability for hydrogen storage. Through a detailed characterization of the obtained composite nanostructured materials (SEM, XPS, HRTEM), we demonstrate hereafter the creation of a chemical link, through the formation of metallic interphases between the supported metal catalyst NPs and the magnesium particles, explaining potentially the improvements previously reported. Additionally, this work opens new routes towards the development of more complex materials, with a possible control of the interface between the supported NPs and their support, opening interesting perspectives, for instance in the field of catalysis.

The Journal of Supercritical Fluids, 2013

ABSTRACT In this work, a two dimensional simulation of segmented micro coflows of CO2 and water i... more ABSTRACT In this work, a two dimensional simulation of segmented micro coflows of CO2 and water in microcapillaries (20 < T (°C) < 50 and 8 < p (MPa) < 16.5) was carried out using a combination of the one-fluid model and the volume of fluid (VOF) method to describe the two-phase flow and a penalty method to account for the wetting property of the capillary walls. The computational work was validated by comparing numerical and experimental results in both the dripping and jetting regimes (Figure 1). The agreement of the calculated pressure difference across the droplet or jet interface with the Laplace-Young’s law was assessed as supplementary criteria. The effects of CO2 / Water interfacial tension (5 < s (mN.m-1) < 35) and wall wettability (contact angle CO2 / wall varying from 0 to 180°) on the segmented water – supercritical CO2 microflows were specially described. It was shown that switching the wall surface from hydrophilic to hydrophobic by tuning the contact angle allows for changing the droplet curvature so that the continuous water phase eventually undergoes a phase inversion resulting in water droplets/slugs formation in a continuous CO2 phase.

International Journal of Chemical Reactor Engineering, 2000

The concepts of green chemistry and sustainable development are being considered more and more du... more The concepts of green chemistry and sustainable development are being considered more and more due to the evolution of regulations and mentalities. In this context, the development of supercritical fluid technologies should go on to evolve in the right direction.

Industrial & Engineering Chemistry Research, 2010

The development of chemically compatible microsystems that can operate across expanded process co... more The development of chemically compatible microsystems that can operate across expanded process conditions, such as high pressures (HP) and high temperatures (HT), is of great interest for many applications, including high pressure chemistry and hydrothermal and supercritical fluid processes. We present a methodology for the successful design and use of HP/HT microsystems. Key parameters for the fabrication of microreactors and modular fluidic packaging able to withstand severe pressure and temperature conditions (30 MPa, 400°C