Sylvie Calas-Etienne

Aeropectin: Fully Biomass-Based Mechanically Strong and Thermal Superinsulating Aerogel

Monolithic pectin aerogels, aeropectins, were prepared via dissolution-gelation-coagulation and subsequent drying with supercritical CO2. Aeropectin had pore sizes that varied from mesopores to small macropores and compression moduli in the range from 4 to 18 MPa. Aeropectins show plastic deformation up to 60% strain before the pore walls collapse. Pectin aerogels have a thermal conductivity below that of air in ambient conditions, making them new thermal superinsulating fully biomass-based materials. The contribution of gas and solid conduction plus radiative heat transfer were determined and discussed.

Mechanical Properties and Brittle Behavior of Silica Aerogels

Sets of silica gels: aerogels, xerogels and sintered aerogels, have been studied in the objective to understand the mechanical behavior of these highly porous solids. The mechanical behaviour of gels is described in terms of elastic and brittle materials, like glasses or ceramics. The magnitude of the elastic and rupture modulus is several orders of magnitude lower compared to dense glass. The mechanical behaviours (elastic and brittle) are related to the same kinds of gel characteristics: pore volume, silanol content and pore size. Elastic modulus depends strongly on the volume fraction of pores and on the condensation reaction between silanols. Concerning the brittleness features: rupture modulus and toughness, it is shown that pores size plays an important role. Pores can be considered as flaws in the terms of fracture mechanics and the flaw size is related to the pore size. Weibull’s theory is used to show the statistical nature of flaw. Moreover, stress corrosion behaviour is studied as a function of environmental conditions (water and alcoholic atmosphere) and temperature.

Synthesis and characterization of a photosensitive organic–inorganic, hybrid positive resin type material: application to the manufacture of microfluidic devices by laser writing

A positive working and chemical amplified photosensitive organic–inorganic hybrid material based on PAA polymer with a lower molecular weight, 1,3,5-tris[(2-vinyloxy)ethoxy]benzene (TVEB) as a crosslinking dissolution inhibitor, a VEPTES pre-hydrolysed as an organic–inorganic material and a PAG photoacid generator was developed. The TVEB was prepared by coupling 1,3,5-trihydroxybenzene and 2-chloroethyl vinyl ether. The hybrid photosensitive material showed sensitivity when exposed to UV light at 375 nm followed by development with a 2.38 wt% aqueous solution of TMAH at room temperature. The synthesis of the material was followed by FTIR spectroscopy to follow the crosslinking of the vinyl ether group from TVEB and VEPTES with the carboxylic group of the PAA polymer.

Design and controlled synthesis by dual polymerization of new organic–inorganic hybrid material for photonic devices

Organic–inorganic hybrid material was synthesized by double polymerization processes i.e. a sol–gel process and organic polymerization respectively. For this study, hybrid monomer, 4-vinyl ether-phenyltriethoxysilane (VEPTES) was used as starting building block. First, the silica matrix with tunable ratio of siloxane and silanol units was synthesized by a sol–gel process under acidic conditions and the organic network was formed by cationic photopolymerization of vinyl ether groups. Mineral and organic polymerization kinetics were respectively monitored by liquid 29Si-NMR and IR spectroscopy. The effect of the silicate backbone on the organic photopolymerization process was studied and elucidated. The optical performance of this new hybrid material has been studied using the near-infrared spectroscopy.

New organic–inorganic hybrid material based on a poly(amic acid) oligomer: a promising opportunity to obtain microfluidic devices by a photolithographic process

Miniaturized total analysis systems are becoming a powerful tool for analytical and bioanalytical applications. Biological and chemical sensors for health and environmental applications often require adaptable technologies. A flexible and low-cost process using a material with efficient mechanical and thermal properties is necessary. Organic–inorganic hybrid materials offer the advantages of the organic content and the inorganic matrix. In this study, a microfluidic sensor is fabricated on a new hybrid photosensitive material using an accurate and flexible process based on pulsed UV laser lithography. The material is based on poly(amic acid) (PAA) oligomer with lower molecular weight and lower cost, 1,3,5-tris[(2-vinyloxy)ethoxy]benzene (TVEB) as a crosslinking dissolution inhibitor, pre-hydrolysed 4-vinylether-phenyltriethoxysilane (VEPTES) as an organic–inorganic material, and a photoacid generator (PAG). A fine positive pattern is fabricated in a 3 μm thick film with laser writing using 125 μW energy. The synthesized hybrid material is characterized by nano indentation to analyze the force required to indent the coating and to predict the coating hardness and elastic modulus. Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are used to evaluate its thermal stability. Scanning electron microscopy (SEM) is performed to verify the homogeneity of the material. These newly prepared photosensitive hybrid materials can open the way for potential applications in the fabrication of microfluidic devices.