Pascal Etienne - Academia.edu (original) (raw)

Papers by Pascal Etienne

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, 2006

Le Centre pour la Communication Scientifique Directe - HAL - Archive ouverte HAL, 2006

Le Centre pour la Communication Scientifique Directe - HAL - memSIC, Jan 31, 2018

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Dec 13, 2007

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, 2006

Le Centre pour la Communication Scientifique Directe - HAL - Inria, Dec 12, 2006

Crystals, 2021

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass ... more We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attr...

L'objectif de ce travail de these est double : d'une part mesurer les proprietes mecaniqu... more L'objectif de ce travail de these est double : d'une part mesurer les proprietes mecaniques de couches hybrides a base d'organosiloxanes et de silice colloidale et ensuite de lier ces caracteristiques mecaniques a leur structure. La partie bibliographique est divisee en deux chapitres : le premier porte sur la description de la technique de nanoindentation et son utilisation pour obtenir les proprietes mecaniques des materiaux elastoplastiques. Le second est consacre aux materiaux hybrides organiques-inorganiques, a leur elaboration sous forme de couches et enfin a leur caracterisation structurale par spectroscopie dans le domaine de l'infrarouge et Resonance Magnetique Nucleaire du 29Si. L'etude experimentale est egalement divisee en deux chapitres : le chapitre I est consacre a l'elaboration des sols permettant la fabrication des couches et a la caracterisation structurale a la fois des sols (par RMN du 29Si en phase liquide) et des depots (par spectroscopi...

Physics and Chemistry of Glasses, 2000

Crack growth in porous and transparent silica aerogels has been measured within the range 10 nm/s... more Crack growth in porous and transparent silica aerogels has been measured within the range 10 nm/s-0.3 m/s using optical devices. The surface nature of aerogels is hydrophobic. It may be converted in hydrophilic material by an oxidation heat treatment. For low stress intensity factor both aerogels show a stress corrosion mechanism analogous to that observed in dense silica glass subjected to alkaline aqueous solutions. However, the crack rate in oxidised silica aerogels is one hundred times higher than that observed in as obtained hydrophobic aerogels. For higher stress intensity factor values the crack rates of both aerogels superimpose indicating that the crack ignores details of aerogel structure.

The present invention relates to a photocurable composition capable of being obtained by a proces... more The present invention relates to a photocurable composition capable of being obtained by a process comprising the steps of: (a) reaction of hydrolysis and condensation of a [(epoxycycloalkyl) alkyl] -trialcoxysilane organoaqueux in solution in a medium containing water and at least one solvent miscible with water at a pH less than 4, and at a combination of temperature / time sufficient to obtain a solution of a hybrid organomineral prepolymer having on average at least four groups (epoxycycloalkyl) alkyl, preferably 4 to 10 groups (epoxycycloalkyl) alkyl group per molecule, (b) cooling the prepolymer composition polyepoxy obtained to a temperature between 15 and 25 degrees C, (c) adding to said composition of at least one cationic polymerization photoinitiator and at least one photosensitizer having a maximum absorption at a wavelength between 300 and 420 nm, and optionally addit ion of a surfactant (d) stirring of the resulting composition for a period of between 10 and 120 minute...

Molecules, 2021

Ordered mesoporous materials and their modification with multiple functional groups are of wide s... more Ordered mesoporous materials and their modification with multiple functional groups are of wide scientific interest for many applications involving interaction with biological systems and biomolecules (e.g., catalysis, separation, sensor design, nano-science or drug delivery). In particular, the immobilization of enzymes onto solid supports is highly attractive for industry and synthetic chemistry, as it allows the development of stable and cheap biocatalysts. In this context, we developed novel silylated amino acid derivatives (Si-AA-NH2) that have been immobilized onto SBA-15 materials in biocompatible conditions avoiding the use of toxic catalyst, solvents or reagents. The resulting amino acid-functionalized materials (SBA-15@AA) were characterized by XRD, TGA, EA, Zeta potential, nitrogen sorption and FT-IR. Differences of the physical properties (e.g., charges) were observed while the structural ones remained unchanged. The adsorption of the enzyme lysozyme (Lyz) onto the resul...

Journal of Sol-Gel Science and Technology, 2019

In this paper, we present the different characterization techniques used to measure the mechanica... more In this paper, we present the different characterization techniques used to measure the mechanical properties of silica aerogels. The mechanical behaviour of aerogels is generally described in terms of elastic and fragile materials (such as glasses or ceramics) but also in terms of plastic media in compression testing. Because of these very different mechanical behaviors, several types of characterization techniques are proposed in the literature. We first describe the dynamic characterization techniques such as ultrasounds, Brillouin scattering, dynamic mechanical analysis (DMA) to measure the elastic properties: Young's modulus (E) , shear modulus (G), poisson ratio (υ) but also attenuation and internal friction. Thanks to "static" techniques such as three-point bending, uniaxial compression, compression we also access to the elastic modulus (E) and to the rupture strength (σ). The experimental results show that the value of the elastic and fracture moduli measured is several orders of magnitude lower than that of a material without porosity. With regard to the brittleness characteristics, Weibull's analysis is used to show the statistical nature of the fracture resistance. We also present the SENB (single edge notched beam technique) technique to characterize toughness (K1C) and the stress corrosion mechanisms, which are studied in ambient conditions and temperature by the double-cleavage drilled compression experiment (DCDC). In the last part of the paper, we show how, during the isostatic compression test, aerogels behave like plastic materials.The data allow calculating the bulk modulus (K), the amplitude of the plastic deformation and the yield strength (σel), which is the boundary between the elastic and plastic domains. These different techniques allow understanding which parameters influence the overall mechanical behavior of aerogels, such as pore volume, but also pore size, internal connectivity and silanol bounds content. It is shown that pore size plays a very important role; pores can be considered as flaws in the terms of fracture mechanics.

Journal of the American Oil Chemists' Society, 2019

Lipidic polyols based on -hydroxyketone reactive groups were investigated for polyurethane therm... more Lipidic polyols based on -hydroxyketone reactive groups were investigated for polyurethane thermosets. The reactivity of this peculiar secondary alcohol group in triglyceride structure was compared, without use of catalyst, to that of poly(1,2-diol)triglyceride and castor oil to demonstrate the influence of ketone in  position of alcohol group in presence of HDMI for urethanisation rate. The kinetic effect of ketone group was also studied on various lipidic architectures: mono(-hydroxyketone) ester, di(-hydroxyketone) diester and tri(hydroxyketone) triglyceride. The presence of hydrogen bonds in the network coming from urethane, residual alcohol and ketone in hard segments of PU was discussed and correlated to the thermal stability and the soft mechanical properties of the resulting polyurethane thermosets.

EPJ Web of Conferences, 2019

Through the efforts to fuse planar optics and microfluidics in order to produce dye lasers, biose... more Through the efforts to fuse planar optics and microfluidics in order to produce dye lasers, biosensors, trapping and cell sorting device, we can notice the rising interest in optofluidics since early and mid 2000's. However mass production of these devices heavily relies on fast and easy patterning of the constituent material. PDMS, being one of these materials, gained an added value because of its elasticity, hydrophobicity and permeability to gaz. Nonetheless, these specifications are not convenient for all types of applications. The growing capability to use Hybrid Organic-Inorganic materials for the fabrication of integrated optics components and microfluidic channels is what makes this class of materials an ideal candidate for this integration. This work aims to implement, on the same chip, an optical and a microfluidic layer using Sol-Gel processing of Organic-Inorganic materials. The interest in this vertical integration arises from the need to manipulate the fluid in the...

Langmuir, 2019

Microfluidics is one of the most fascinating fields that researchers have been trying to apply in... more Microfluidics is one of the most fascinating fields that researchers have been trying to apply in a large number of scientific disciplines over the past two decades. Among them, the discipline of food and pharmaceutical formulation encountered several obstacles when combined microfluidics and aqueous media. Indeed the physical properties of liquids at micrometric volumes being particular, the droplets generation within microfluidic devices is a big challenge to be met. This focus review is intended to be an initiation for whom would like to generate microdroplets in microfluidic systems involving continuous-aqueous phases. It provides a state-of-the-art of such systems while focusing on the microfluidic devices used, their applications to form a wide variety of emulsions and particles as well as the key role held by the interface between the device channels and the emulsion. The review also leads to reflections on new materials that can be used in microfluidic systems with aqueous-continuous phases.

European Polymer Journal, 2019

A comprehensive characterization of physical-chemical properties and biological interactions of c... more A comprehensive characterization of physical-chemical properties and biological interactions of ca. 200-nm-thick hybrid films based on silylated (inorganic part) castor oil (organic part) is proposed. A series of such nanofilms was fabricated and cross-linked by a sol-gel procedure, and their properties such as hydrophilicity, hardness and water vapour transmission rate were systematically studied as a function of the ratio of silylated agent to castor oil. It was found that the nanofilms have contact angles always below 90°, tunable Young modulus and hardness in the MPa range. Moreover, their water vapour transmission rates are increased by decreasing the silica ratio. The protein adsorption and cytocompatibility were evaluated using model proteins and cells. The adsorption of the proteins bovine serum albumin (BSA) and lysozyme was characterized using a quartz crystal microbalance in energy dissipation mode (QCM-D), and atomic force microscopy (AFM). The combination of the latter provided evidence for the different affinities of the proteins with the films. It was found that BSA and lysozyme form rigid layers on the surface with surface coverage close to 30 %, and that both protein layers decrease their thickness after their dehydration. Finally, cell culture experiments exhibited a good viability of the fibroblasts compared to ultra-low adhesion surfaces, which makes them potential candidates for biomedical applications.

Sol-Gel and Polymer Photonic Devices: A Critical Review, 1997

Abstract The sol-gel process is an interesting alternative to make glass integrated optics compon... more Abstract The sol-gel process is an interesting alternative to make glass integrated optics components. Basically, reasonable performances can be reached with low cost fabrication. The sol-gel process is coupled to an one-step method to imprint channel waveguides as ...

Soft matter, Jan 14, 2017

Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating-free metho... more Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating-free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated using nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored, and finally cytotoxicity tests were performed on fibroblasts ...

Carbohydrate Polymers, 2016

Organic-inorganic functional hybrid materials play a major role in the development of advanced fu... more Organic-inorganic functional hybrid materials play a major role in the development of advanced functional materials and recently have gained growing interest of the worldwide community. In this context, new hybrid organic-inorganic gel consisting of cellulose nanowhisker xanthate (CNWX) and S-H functionalized polypseudorotaxane (PPR) as organic parts of gel and gold nanorods (GNRs) as inorganic cross-linking agent were prepared. Firstly, thiolated ␣-cyclodextrin (␣-CD-SH) was threaded onto poly-(ethylene glycol) bis (mercaptoethanoate ester) (PEG-SH) to give polypseudorotaxane (PPR) and then it reacted with GNRs in the presence of CNWX to give the new hybrid gel material. The new synthesized gel and its components characterized by spectroscopic measurement methods such as FT-IR, UV-vis and NMR spectroscopy. Interestingly, hybrid gel showed new polygonal plate like morphology with 45-60 nm thickness and 400-600 nm width. The obtained gel may have potential application in many fields especially in biomedical applications.

Handbook of Sol-Gel Science and Technology, 2016

Different kinds of structure in alcogels and aerogels (fractal or not fractal) can be synthesized... more Different kinds of structure in alcogels and aerogels (fractal or not fractal) can be synthesized by a control of the chemical parameters and also by different steps in the preparation such as sintering and plastic compaction. The porosity of the gels is affected either by the adjustment of the gelifying concentration, by a precise control of the viscous flow sintering process, or by an isostatic pressure deformation. The different kinds of gels cover the whole range of porosity between 99% and 0%, and their mechanical properties (elastic modulus, strength, toughness) are strongly dependent on the porosity but also on their structure. We follow the mechanical properties of the over the whole process alcogelaerogelglass. They vary by five orders of magnitude as a function of the density, and for the same relative density, the elastic modulus and strength can increase by one order of magnitude due to a change in connectivity. The influence of the sintering process compared to isostatic pressure on the mechanical properties is explained by the associated structural changes.

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, 2006

Le Centre pour la Communication Scientifique Directe - HAL - Archive ouverte HAL, 2006

Le Centre pour la Communication Scientifique Directe - HAL - memSIC, Jan 31, 2018

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Dec 13, 2007

Le Centre pour la Communication Scientifique Directe - HAL - Diderot, 2006

Le Centre pour la Communication Scientifique Directe - HAL - Inria, Dec 12, 2006

Crystals, 2021

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass ... more We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attr...

L'objectif de ce travail de these est double : d'une part mesurer les proprietes mecaniqu... more L'objectif de ce travail de these est double : d'une part mesurer les proprietes mecaniques de couches hybrides a base d'organosiloxanes et de silice colloidale et ensuite de lier ces caracteristiques mecaniques a leur structure. La partie bibliographique est divisee en deux chapitres : le premier porte sur la description de la technique de nanoindentation et son utilisation pour obtenir les proprietes mecaniques des materiaux elastoplastiques. Le second est consacre aux materiaux hybrides organiques-inorganiques, a leur elaboration sous forme de couches et enfin a leur caracterisation structurale par spectroscopie dans le domaine de l'infrarouge et Resonance Magnetique Nucleaire du 29Si. L'etude experimentale est egalement divisee en deux chapitres : le chapitre I est consacre a l'elaboration des sols permettant la fabrication des couches et a la caracterisation structurale a la fois des sols (par RMN du 29Si en phase liquide) et des depots (par spectroscopi...

Physics and Chemistry of Glasses, 2000

Crack growth in porous and transparent silica aerogels has been measured within the range 10 nm/s... more Crack growth in porous and transparent silica aerogels has been measured within the range 10 nm/s-0.3 m/s using optical devices. The surface nature of aerogels is hydrophobic. It may be converted in hydrophilic material by an oxidation heat treatment. For low stress intensity factor both aerogels show a stress corrosion mechanism analogous to that observed in dense silica glass subjected to alkaline aqueous solutions. However, the crack rate in oxidised silica aerogels is one hundred times higher than that observed in as obtained hydrophobic aerogels. For higher stress intensity factor values the crack rates of both aerogels superimpose indicating that the crack ignores details of aerogel structure.

The present invention relates to a photocurable composition capable of being obtained by a proces... more The present invention relates to a photocurable composition capable of being obtained by a process comprising the steps of: (a) reaction of hydrolysis and condensation of a [(epoxycycloalkyl) alkyl] -trialcoxysilane organoaqueux in solution in a medium containing water and at least one solvent miscible with water at a pH less than 4, and at a combination of temperature / time sufficient to obtain a solution of a hybrid organomineral prepolymer having on average at least four groups (epoxycycloalkyl) alkyl, preferably 4 to 10 groups (epoxycycloalkyl) alkyl group per molecule, (b) cooling the prepolymer composition polyepoxy obtained to a temperature between 15 and 25 degrees C, (c) adding to said composition of at least one cationic polymerization photoinitiator and at least one photosensitizer having a maximum absorption at a wavelength between 300 and 420 nm, and optionally addit ion of a surfactant (d) stirring of the resulting composition for a period of between 10 and 120 minute...

Molecules, 2021

Ordered mesoporous materials and their modification with multiple functional groups are of wide s... more Ordered mesoporous materials and their modification with multiple functional groups are of wide scientific interest for many applications involving interaction with biological systems and biomolecules (e.g., catalysis, separation, sensor design, nano-science or drug delivery). In particular, the immobilization of enzymes onto solid supports is highly attractive for industry and synthetic chemistry, as it allows the development of stable and cheap biocatalysts. In this context, we developed novel silylated amino acid derivatives (Si-AA-NH2) that have been immobilized onto SBA-15 materials in biocompatible conditions avoiding the use of toxic catalyst, solvents or reagents. The resulting amino acid-functionalized materials (SBA-15@AA) were characterized by XRD, TGA, EA, Zeta potential, nitrogen sorption and FT-IR. Differences of the physical properties (e.g., charges) were observed while the structural ones remained unchanged. The adsorption of the enzyme lysozyme (Lyz) onto the resul...

Journal of Sol-Gel Science and Technology, 2019

In this paper, we present the different characterization techniques used to measure the mechanica... more In this paper, we present the different characterization techniques used to measure the mechanical properties of silica aerogels. The mechanical behaviour of aerogels is generally described in terms of elastic and fragile materials (such as glasses or ceramics) but also in terms of plastic media in compression testing. Because of these very different mechanical behaviors, several types of characterization techniques are proposed in the literature. We first describe the dynamic characterization techniques such as ultrasounds, Brillouin scattering, dynamic mechanical analysis (DMA) to measure the elastic properties: Young's modulus (E) , shear modulus (G), poisson ratio (υ) but also attenuation and internal friction. Thanks to "static" techniques such as three-point bending, uniaxial compression, compression we also access to the elastic modulus (E) and to the rupture strength (σ). The experimental results show that the value of the elastic and fracture moduli measured is several orders of magnitude lower than that of a material without porosity. With regard to the brittleness characteristics, Weibull's analysis is used to show the statistical nature of the fracture resistance. We also present the SENB (single edge notched beam technique) technique to characterize toughness (K1C) and the stress corrosion mechanisms, which are studied in ambient conditions and temperature by the double-cleavage drilled compression experiment (DCDC). In the last part of the paper, we show how, during the isostatic compression test, aerogels behave like plastic materials.The data allow calculating the bulk modulus (K), the amplitude of the plastic deformation and the yield strength (σel), which is the boundary between the elastic and plastic domains. These different techniques allow understanding which parameters influence the overall mechanical behavior of aerogels, such as pore volume, but also pore size, internal connectivity and silanol bounds content. It is shown that pore size plays a very important role; pores can be considered as flaws in the terms of fracture mechanics.

Journal of the American Oil Chemists' Society, 2019

Lipidic polyols based on -hydroxyketone reactive groups were investigated for polyurethane therm... more Lipidic polyols based on -hydroxyketone reactive groups were investigated for polyurethane thermosets. The reactivity of this peculiar secondary alcohol group in triglyceride structure was compared, without use of catalyst, to that of poly(1,2-diol)triglyceride and castor oil to demonstrate the influence of ketone in  position of alcohol group in presence of HDMI for urethanisation rate. The kinetic effect of ketone group was also studied on various lipidic architectures: mono(-hydroxyketone) ester, di(-hydroxyketone) diester and tri(hydroxyketone) triglyceride. The presence of hydrogen bonds in the network coming from urethane, residual alcohol and ketone in hard segments of PU was discussed and correlated to the thermal stability and the soft mechanical properties of the resulting polyurethane thermosets.

EPJ Web of Conferences, 2019

Through the efforts to fuse planar optics and microfluidics in order to produce dye lasers, biose... more Through the efforts to fuse planar optics and microfluidics in order to produce dye lasers, biosensors, trapping and cell sorting device, we can notice the rising interest in optofluidics since early and mid 2000's. However mass production of these devices heavily relies on fast and easy patterning of the constituent material. PDMS, being one of these materials, gained an added value because of its elasticity, hydrophobicity and permeability to gaz. Nonetheless, these specifications are not convenient for all types of applications. The growing capability to use Hybrid Organic-Inorganic materials for the fabrication of integrated optics components and microfluidic channels is what makes this class of materials an ideal candidate for this integration. This work aims to implement, on the same chip, an optical and a microfluidic layer using Sol-Gel processing of Organic-Inorganic materials. The interest in this vertical integration arises from the need to manipulate the fluid in the...

Langmuir, 2019

Microfluidics is one of the most fascinating fields that researchers have been trying to apply in... more Microfluidics is one of the most fascinating fields that researchers have been trying to apply in a large number of scientific disciplines over the past two decades. Among them, the discipline of food and pharmaceutical formulation encountered several obstacles when combined microfluidics and aqueous media. Indeed the physical properties of liquids at micrometric volumes being particular, the droplets generation within microfluidic devices is a big challenge to be met. This focus review is intended to be an initiation for whom would like to generate microdroplets in microfluidic systems involving continuous-aqueous phases. It provides a state-of-the-art of such systems while focusing on the microfluidic devices used, their applications to form a wide variety of emulsions and particles as well as the key role held by the interface between the device channels and the emulsion. The review also leads to reflections on new materials that can be used in microfluidic systems with aqueous-continuous phases.

European Polymer Journal, 2019

A comprehensive characterization of physical-chemical properties and biological interactions of c... more A comprehensive characterization of physical-chemical properties and biological interactions of ca. 200-nm-thick hybrid films based on silylated (inorganic part) castor oil (organic part) is proposed. A series of such nanofilms was fabricated and cross-linked by a sol-gel procedure, and their properties such as hydrophilicity, hardness and water vapour transmission rate were systematically studied as a function of the ratio of silylated agent to castor oil. It was found that the nanofilms have contact angles always below 90°, tunable Young modulus and hardness in the MPa range. Moreover, their water vapour transmission rates are increased by decreasing the silica ratio. The protein adsorption and cytocompatibility were evaluated using model proteins and cells. The adsorption of the proteins bovine serum albumin (BSA) and lysozyme was characterized using a quartz crystal microbalance in energy dissipation mode (QCM-D), and atomic force microscopy (AFM). The combination of the latter provided evidence for the different affinities of the proteins with the films. It was found that BSA and lysozyme form rigid layers on the surface with surface coverage close to 30 %, and that both protein layers decrease their thickness after their dehydration. Finally, cell culture experiments exhibited a good viability of the fibroblasts compared to ultra-low adhesion surfaces, which makes them potential candidates for biomedical applications.

Sol-Gel and Polymer Photonic Devices: A Critical Review, 1997

Abstract The sol-gel process is an interesting alternative to make glass integrated optics compon... more Abstract The sol-gel process is an interesting alternative to make glass integrated optics components. Basically, reasonable performances can be reached with low cost fabrication. The sol-gel process is coupled to an one-step method to imprint channel waveguides as ...

Soft matter, Jan 14, 2017

Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating-free metho... more Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating-free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated using nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored, and finally cytotoxicity tests were performed on fibroblasts ...

Carbohydrate Polymers, 2016

Organic-inorganic functional hybrid materials play a major role in the development of advanced fu... more Organic-inorganic functional hybrid materials play a major role in the development of advanced functional materials and recently have gained growing interest of the worldwide community. In this context, new hybrid organic-inorganic gel consisting of cellulose nanowhisker xanthate (CNWX) and S-H functionalized polypseudorotaxane (PPR) as organic parts of gel and gold nanorods (GNRs) as inorganic cross-linking agent were prepared. Firstly, thiolated ␣-cyclodextrin (␣-CD-SH) was threaded onto poly-(ethylene glycol) bis (mercaptoethanoate ester) (PEG-SH) to give polypseudorotaxane (PPR) and then it reacted with GNRs in the presence of CNWX to give the new hybrid gel material. The new synthesized gel and its components characterized by spectroscopic measurement methods such as FT-IR, UV-vis and NMR spectroscopy. Interestingly, hybrid gel showed new polygonal plate like morphology with 45-60 nm thickness and 400-600 nm width. The obtained gel may have potential application in many fields especially in biomedical applications.

Handbook of Sol-Gel Science and Technology, 2016

Different kinds of structure in alcogels and aerogels (fractal or not fractal) can be synthesized... more Different kinds of structure in alcogels and aerogels (fractal or not fractal) can be synthesized by a control of the chemical parameters and also by different steps in the preparation such as sintering and plastic compaction. The porosity of the gels is affected either by the adjustment of the gelifying concentration, by a precise control of the viscous flow sintering process, or by an isostatic pressure deformation. The different kinds of gels cover the whole range of porosity between 99% and 0%, and their mechanical properties (elastic modulus, strength, toughness) are strongly dependent on the porosity but also on their structure. We follow the mechanical properties of the over the whole process alcogelaerogelglass. They vary by five orders of magnitude as a function of the density, and for the same relative density, the elastic modulus and strength can increase by one order of magnitude due to a change in connectivity. The influence of the sintering process compared to isostatic pressure on the mechanical properties is explained by the associated structural changes.