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Synthesis and properties of organic – inorganic hybrid materials based on glycerol / Ignacio E. dell’Erba in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7793–7799 Titre : Synthesis and properties of organic – inorganic hybrid materials based on glycerol Type de document : texte imprimé Auteurs : Ignacio E. dell’Erba, Auteur ; Cristina E. Hoppe, Auteur ; Roberto J. J. Williams, Auteur Année de publication : 2012 Article en page(s) : pp. 7793–7799 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Organic–inorganic  hybrid  materials Résumé : The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic–inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol–gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic–inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6° for r = 0.75 to 95.1° for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54–70 °C range. The relatively intense tan δ peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa·K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300393n [article] Synthesis and properties of organic – inorganic hybrid materials based on glycerol [texte imprimé] / Ignacio E. dell’Erba, Auteur ; Cristina E. Hoppe, Auteur ; Roberto J. J. Williams, Auteur . - 2012 . - pp. 7793–7799. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7793–7799 Mots-clés : Organic–inorganic  hybrid  materials Résumé : The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic–inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol–gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic–inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6° for r = 0.75 to 95.1° for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54–70 °C range. The relatively intense tan δ peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa·K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300393n

Thermodynamic model of liquid−liquid phase equilibrium in solutions of alkanethiol-coated nanoparticles / Ezequiel R. Soulé in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7008–7016 Titre : Thermodynamic model of liquid−liquid phase equilibrium in solutions of alkanethiol-coated nanoparticles Type de document : texte imprimé Auteurs : Ezequiel R. Soulé, Auteur ; Cristina E. Hoppe, Auteur ; Julio Borrajo, Auteur Année de publication : 2010 Article en page(s) : pp 7008–7016 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Thermodynamic  Liquid  Phase  Equilibrium. Résumé : A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs) and low-molecular-weight (nonpolymeric) solvent is developed, and calculations of liquid−liquid phase equilibria for different values of NP core radius, alkanethiol chain length, solvent molar volume, and alkanethiol−solvent interaction parameter, are presented. The model takes into account the swelling of the organic coronas and the dispersion of particles with swollen coronas in the solvent. The energetic interaction between alkyl chains and solvent is considered, both within the corona and between the outer alkyl segments and free solvent. Swelling involves mixing of alkanethiol chains and solvent in the corona and stretching of the organic chains. Dispersion considers an entropic contribution based on the Carnahan−Starling equation of state and an enthalpic term calculated considering the surface contacts between alkyl segments placed in the external boundary of the corona and the molecules of free solvent. Two different kinds of phase equilibrium are found. One of them, observed at high values of the interaction parameter, is the typical liquid−liquid equilibrium for compact NPs in a poor solvent where a complete phase separation is observed when cooling (increasing the interaction parameter). The second liquid−liquid equilibrium is observed at low values of the interaction parameter, where swelling of coronas is favored. In this region two different phases coexist: one more concentrated in NPs that exhibit relatively compact coronas and the other one more diluted in NPs with extended coronas. In diluted solutions of NPs the deswelling of the fully extended coronas takes place abruptly in a very small temperature range, leading to a solution of compact NPs. This critical transition might find practical applications similar to those found for the abrupt shrinkage of hydrogels at a critical temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901784r [article] Thermodynamic model of liquid−liquid phase equilibrium in solutions of alkanethiol-coated nanoparticles [texte imprimé] / Ezequiel R. Soulé, Auteur ; Cristina E. Hoppe, Auteur ; Julio Borrajo, Auteur . - 2010 . - pp 7008–7016. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 7008–7016 Mots-clés : Thermodynamic  Liquid  Phase  Equilibrium. Résumé : A thermodynamic model for a mixture of alkanethiol-coated nanoparticles (NPs) and low-molecular-weight (nonpolymeric) solvent is developed, and calculations of liquid−liquid phase equilibria for different values of NP core radius, alkanethiol chain length, solvent molar volume, and alkanethiol−solvent interaction parameter, are presented. The model takes into account the swelling of the organic coronas and the dispersion of particles with swollen coronas in the solvent. The energetic interaction between alkyl chains and solvent is considered, both within the corona and between the outer alkyl segments and free solvent. Swelling involves mixing of alkanethiol chains and solvent in the corona and stretching of the organic chains. Dispersion considers an entropic contribution based on the Carnahan−Starling equation of state and an enthalpic term calculated considering the surface contacts between alkyl segments placed in the external boundary of the corona and the molecules of free solvent. Two different kinds of phase equilibrium are found. One of them, observed at high values of the interaction parameter, is the typical liquid−liquid equilibrium for compact NPs in a poor solvent where a complete phase separation is observed when cooling (increasing the interaction parameter). The second liquid−liquid equilibrium is observed at low values of the interaction parameter, where swelling of coronas is favored. In this region two different phases coexist: one more concentrated in NPs that exhibit relatively compact coronas and the other one more diluted in NPs with extended coronas. In diluted solutions of NPs the deswelling of the fully extended coronas takes place abruptly in a very small temperature range, leading to a solution of compact NPs. This critical transition might find practical applications similar to those found for the abrupt shrinkage of hydrogels at a critical temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901784r