Sabine Manet - Academia.edu (original) (raw)

Papers by Sabine Manet

ACS Nano, 2016

Blue phases (BPs), a distinct class of liquid crystals (LCs) with 3D periodic ordering of double ... more Blue phases (BPs), a distinct class of liquid crystals (LCs) with 3D periodic ordering of double twist cylinders involving orthogonal helical director twists, have been theoretically studied as potential templates for tunable colloidal crystals. Here, we report the spontaneous formation of thermally reversible, cubic crystal nanoparticle (NP) assemblies in BPs. Gold NPs, functionalized to be highly miscible in cyanobiphenyl-based LCs, were dispersed in BP mixtures and characterized by polarized optical microscopy and synchrotron small-angle X-ray scattering (SAXS). The NPs assemble by selectively migrating to periodic strong trapping sites in the BP disclination lines. The NP lattice, remarkably robust given the small particle size (4.5 nm diameter), is commensurate with that of the BP matrix. At the BP I to BP II phase transition, the NP lattice reversibly switches between two different cubic structures. The simultaneous presence of two different symmetries in a single material presents an interesting opportunity to develop novel dynamic optical materials.

The Journal of Physical Chemistry B, 2011

Langmuir, 2013

The effect of counterions was investigated to probe the principal ionic effects on the solubility... more The effect of counterions was investigated to probe the principal ionic effects on the solubility in water and melting behavior of cationic gemini surfactants. We focused on two types of counterions: (1) small inorganic counterions that are typically taken from the Hofmeister series were studied to focus on the effect of ion type and (2) n-alkylcarboxylate counterions were studied to focus on the effect of the hydrophobicity of counterions. The Krafft temperature (T k) and melting temperature (T m) were obtained by conductivity measurements, calorimetric measurements, and optical microscopy observation. The results clearly indicate that T k , which represents the solubility of surfactants, is not determined by a single parameter of ions such as the hydration free energy, as is too often assumed, but rather by the combined effects between the hydrophobicity of anions associated with other effects such as the polarizability, dehydrated ion size, and ionic morphology. In parallel, our observation demonstrated that all of the surfactants showed a transition from a crystalline phase to a thermotropic liquid-crystalline phase at around ca. 70°C, which transformed to an isotropic liquid phase at around ca. 150°C, and that the transition temperatures depended strongly on the counterion type. The counterion effects on the solubilization and melting behaviors were then compared with micellization properties that have been reported previously. These results provide new insight into understanding the effect of ions on the delicate balance of forces controlling the solution properties and aggregate morphology of charged amphiphilic molecules. Specifically, the solubilization properties of these cationic surfactants with various counterions were determined mainly by the subtle interplay between the hydration of counterions and the dissociation energies (stability of crystallinity) of the ion pair.

Biomacromolecules, 2011

We explored the behavior and the characteristics of xyloglucan polysaccharide chains extracted fr... more We explored the behavior and the characteristics of xyloglucan polysaccharide chains extracted from tamarind seeds in aqueous media. The initial solubilization is achieved by using a 0.01 M NaOH solution. The absence of compact aggregates in the solution and the average molecular mass of the individual chains were unambiguously demonstrated by size exclusion chromatography with multi-angle light scattering detection. The composition and the stability of the solution were quantitatively checked over weeks by using liquid state nuclear magnetic resonance with DMSO as internal standard. The conformational characteristics of the chains were measured using nondestructive small-angle neutron scattering (SANS). The unambiguous determination of the Flory exponent (ν = 0.588) by SANS enabled us to directly prove that xyloglucan chains in water behave like semiflexible worm-like chains with excluded volume statistics (good solvent), contrary to most of the neutral water-soluble polymer chains that rather exhibit Gaussian statistics (θ-solvent). In addition to the Flory exponent, the persistence length l p and the cross section of the chains were also determined by SANS with utmost precision, with values of 80 and of 7 Å, respectively, which provides a complete description of the conformational characteristics of XG chains at all relevant length scales.

Langmuir, 2012

In situ time-resolved SAXS study of the formation of mesostructured organically-modified silicas ... more In situ time-resolved SAXS study of the formation of mesostructured organically-modified silicas through modeling of micelles evolution during surfactant-templated self-assembly

The Journal of Physical Chemistry B, 2015

The micellar structure of sophorolipids, a glycolipid bolaamphiphile, is analyzed using a combina... more The micellar structure of sophorolipids, a glycolipid bolaamphiphile, is analyzed using a combination of Small Angle X-ray Scattering (SAXS), Small Angle Neutron Scattering (SANS) and Molecular Dynamics (MD) simulations. Numerical modeling of SAXS curves shows that micellar morphology in the non-charged system (pH< 5) is made of prolate ellipsoids of revolution with core-shell morphology. Opposed to most surfactant systems, the hydrophilic shell has a non-homogeneous distribution of matter: the shell thickness in the axial direction of the ellipsoid is found to be practically zero, while it measures about 12 Å at its cross-section, thus forming a "coffee bean" like shape. The use of contrast matching SANS experiment shows that the hydrophobic component of sophorolipids is actually distributed in 2 a narrow spheroidal region in the micellar core. These data seem to indicate a complex distribution of sophorolipids within the micelle, divided into at least three domains: a pure hydrophobic core, a hydrophilic shell and a region of less defined composition in the axial direction of the ellipsoid. To account for these results, we make the hypothesis that sophorolipid molecules acquire various configurations within the micelle including bent and linear, crossing the micellar core. These results are confirmed by MD simulations which do show the presence of multiple sophorolipid configurations when passing from spherical to ellipsoidal aggregates. Finally, we also used Rb + and Sr 2+ counterions in combination with Anomalous SAXS experiments to probe the distribution of the COOgroup of sophorolipids upon small pH increase (5 < pH < 7), where repulsive intermicellar interactions become important. The poor ASAXS signal shows that the COOgroups are rather diffused in the broad hydrophilic shell rather than at the outer micellar/water interface.

Des tensioactifs dimeriques cationiques ont ete etudies en faisant varier la nature du contre-ion... more Des tensioactifs dimeriques cationiques ont ete etudies en faisant varier la nature du contre-ion afin de determiner quels sont les effets ioniques qui influencent principalement leurs proprietes d'agregation. La methode de synthese de ces molecules a ete adaptee afin de permettre l'investigation d'une large variete de systemes se distinguant par leur contre-ion. La micellisation de ces tensioactifs a fait l'objet d'une etude par conductimetrie qui a permis de montrer l'influence preponderante de l'hydrophobie du contre-ion associee a des effets secondaires tels que l'hydratation ou la morphologie du contre-ion. Nous avons aussi montre comment l'utilisation d'un colorant, l'Orange de Methyle, peut s'averer etre un outil d'investigation de l'hydratation et de l'ionisation des micelles. La solubilite de ces tensioactifs dans l'eau a egalement ete examinee a travers l'etude de leur temperature de Krafft en fonction du ...

The Review of scientific instruments, 2017

We present a small-angle coherent x-ray scattering technique used for measuring flow velocities i... more We present a small-angle coherent x-ray scattering technique used for measuring flow velocities in slow moving materials. The technique is an extension of X-ray Photon Correlation Spectroscopy (XPCS): It involves mixing the scattering from moving tracer particles with a static reference that heterodynes the signal. This acts to elongate temporal effects caused by flow in homodyne measurements, allowing for a more robust measurement of flow properties. Using coherent x-ray heterodyning, velocities ranging from 0.1 to 10 μm/s were measured for a viscous fluid pushed through a rectangular channel. We describe experimental protocols and theory for making these Poiseuille flow profile measurements and also develop the relevant theory for using heterodyne XPCS to measure velocities in uniform and Couette flows.

Studies in Surface Science and Catalysis, 2008

Time-resolved in situ Small Angle Neutron Scattering (SANS) investigations have provided direct e... more Time-resolved in situ Small Angle Neutron Scattering (SANS) investigations have provided direct experimental evidence for the initial steps in the formation of the SBA-15 mesoporous material, prepared using the non-ionic tri-block copolymer Pluronic 123 and TEOS as silica precursor. Upon time, three steps take place during the cooperative self-assembly of the Pluronic micelles and the silica species. First, the hydrolysis

Macromolecules, 2006

... Sabine Manet, Carmen Tibirna, Julie Boivin, Christine Delabroye, and Josée Brisson*. Départem... more ... Sabine Manet, Carmen Tibirna, Julie Boivin, Christine Delabroye, and Josée Brisson*. Département de chimie, Centre de recherche en sciences et ingénierie des macromolécules, Faculté des sciences et de génie, Université Laval, Québec, Québec, Canada G1K 7P4. ...

Biophysical Journal, 2007

A phosphatidylcholine lipid (PC) containing a biphenyl group in one of its acyl chains (1-tetrade... more A phosphatidylcholine lipid (PC) containing a biphenyl group in one of its acyl chains (1-tetradecanoyl-2-(4-(4-biphenyl)butanoyl)-sn-glycero-3-PC, TBBPC) was successfully synthesized with high yield. Water mixtures of TBBPC with a short-chain C 6 lipid, dicaproyl-PC (DCPC), lead to bicelle systems formation. Freeze-fracture electron microscopy evidenced the presence of flat bilayered disks of 800 Å diameter for adequate composition, hydration, and temperature conditions. Because of the presence of the biphenyl group, which confers to the molecule a positive magnetic anisotropy Dx, the disks align with their normal, n, parallel to the magnetic field B 0 , as directly detected by 31 P, 14 N, 2 H solid-state NMR and also using small-angle x-ray scattering after annealing in the field. Temperature-composition and temperature-hydration diagrams were established. Domains where disks of TBBPC/DCPC align with their normal parallel to the field were compared to chain-saturated lipid bicelles made of DMPC(dimyristoylPC)/DCPC, which orient with their normal perpendicular to B 0 . TBBPC/DCPC bicelles exist on a narrow range of long-versus short-chain lipid ratios (3%) but over a large temperature span around room temperature (10-75°C), whereas DMPC/ DCPC bicelles exhibit the reverse situation, i.e., large compositional range (22%) and narrow temperature span (25-45°C). The two types of bicelles present orienting properties up to 95% dilution but with the peculiarity that water trapped in biphenyl bicelles exhibits ordering properties twice as large as those observed in the saturated-chains analog, which offers very interesting properties for structural studies on hydrophilic or hydrophobic embedded biomolecules.

Journal of Colloid and Interface Science, 2005

Cationic gemini surfactants having nucleotides as counterions (called nucleo-gemini hereafter) we... more Cationic gemini surfactants having nucleotides as counterions (called nucleo-gemini hereafter) were synthesized and their aggregation behavior at air-water surfaces as well as in bulk solutions were studied. Fluid solutions of these nucleo-gemini surfactants show transitions to hydrogels upon addition of complementary nucleoside bases or other nucleo-gemini surfactants having complementary bases as counterions. The FTIR-ATR measurements show that the carboxylate groups of uridine form hydrogen bonds with the amine groups of adenosine. The aggregation behavior was also confirmed at the air-water interface by Brewster angle microscopy as well as surface pressure measurements; the monolayer of a gemini nucleotide was observed to undergo a transition to multilayers when nucleosides with complementary bases were added into the subphase. Isotherm curves of surface pressure monitored in parallel show a decrease in molecular area upon addition of such nucleosides.

Langmuir, 2007

A new family of self-assembling systems based on nucleoamphiphiles is described. Nano to micromet... more A new family of self-assembling systems based on nucleoamphiphiles is described. Nano to micrometric left-handed helix formation in aqueous solution was induced simply by complexing a GMP or an AMP with a nonchiral monocationic amphiphile. The assembling behavior such as micellar formation, monolayer at air-water interface, as well as the aggregates in solution of these nucleoamphiphiles are strongly influenced by the presence of nucleosides in solution. The observed effects depend on the properties of complexed nucleotides and nucleosides with a complex mixture of π stacking, hydrophobicity of the bases, and hydrogen bonding.

Langmuir, 2010

The effect of counterions was investigated and analyzed to probe the principal ionic effects infl... more The effect of counterions was investigated and analyzed to probe the principal ionic effects influencing the micellization behavior of dimeric cationic surfactant ethanediylbis(dimethyltetradecylammonium), referred to as gemini 14-2-14. The 30 counterions were classified to four different families depending on their nature: (1) small and inorganic counterions which are typically taken from the Hofmeister series were studied to focus on the effect of ion type; (2) n-alkyl carboxylate counterions were studied to focus on the effect of the hydrophobicity of counterions; (3) aromatic carboxylate counterions were included to focus on the effect of the position of substitutions; and (4) other counterions were included in order to shed light on other parameters. By investigating the critical micelle concentration (CMC), ionization degree of micelle (R), free energy of micellization (ΔG M ), and aggregation numbers N of the gemini surfactant with these different types of anions, we demonstrated the effect of different ion properties independently. This approach allowed us to describe the effect of counterions on the micellization behavior of the gemini surfactant in terms of complex interplay between hydrophobicity of anions and other ion properties such as counterion hydration, interfacial packing of ions, and ionic morphology. Indeed, our results clearly demonstrate that a counterion effect on micellization properties cannot be described as a result of one single parameter of ions, as is too often assumed, but rather the balancing effects cooperatively affect the propensity of counterions to form ion pairs with surfactant headgroups and the entropy gain upon micellization. These results provide new insight in understanding the effect of ions on the delicate balance of forces controlling aggregate morphology and solution properties of charged amphiphilic molecules.

Journal of Physical Chemistry B, 2008

Understanding ion specific effects on the solution properties of association colloids is a major ... more Understanding ion specific effects on the solution properties of association colloids is a major unsolved problem, and we are studying the chemistry of gemini surfactants in the gas-phase by mass spectrometry and density functional theory (DFT) to probe ion specific effects in the absence of water. Products from gas-phase fragmentation chemistry of dication-monoanion pairs, M 2+ X -, of C 16 H 33 (CH 3 ) 2 N + -(CH 2 ) n -+ N(CH 3 ) 2 C 16 H 33 · 2Xgemini surfactants were determined by using sequential collision induced dissociation mass spectrometry. The spacer length "n" was systematically varied (n ) 2, 3, 4, and 6) for each counterion investigated (X -) F -, Br -, Cl -, I -, NO 3 -, CF 3 CO 2 -, and PF 6 -). The M 2+ Xpairs fragment into monocationic products from competing E2 and S N 2 pathways that are readily quantified by tandem MS. The dominant reaction pathway depends on dication and anion structure because it switches from E2 to S N 2 with decreasing anion basicity and increasing spacer length. For spacer lengths n ) 4 and 6, the major S N 2 product shifts from attack at methylene to methyl on the quaternary ammonium group. DFT calculations of gemini headgroup model bolaform salts, CH 3 (CH 3 ) 2 N + -(CH 2 ) n -+ N(CH 3 ) 2 CH 3 · 2X -(X -) F -, Cl -, Br -, and I -, n ) 2-4), primarily of activation enthalpies, ∆H ‡ , but also of free energies and entropies for the dication-monoanion pairs, M 2+ X -, provide qualitative explanations for the MS structure-reactivity patterns. ∆H ‡ values for S N 2 reactions are independent of Xtype and spacer length, while E2 reactions show a significant increase in ∆H ‡ with decreasing anion basicity and a modest increase with spacer length. Comparisons with the ∆H ‡ values of model CH 3 CH 2 (CH 3 ) 3 N + Xhalides show that the second charge on the dicationic ion pairs does not significantly affect ∆H ‡ and that the change in distance between the nucleophile and leaving group in the ground and transition states structures in S N 2 reactions is approximately constant indicating that ∆H ‡ is governed primarily by electrostatic interactions. †