Molecular Hydrogels from Bolaform Amino Acid Derivatives: A Structure–Properties Study Based on the Thermodynamics of Gel Solubilization
Impacto
Scholar |
Otros documentos de la autoría: Nebot Carda, Vicent J.; Armengol Fernández, José; Smets, Johan; Fernández Prieto, Susana; Escuder, Beatriu; Miravet, Juan
Metadatos
Mostrar el registro completo del ítemcomunitat-uji-handle:10234/9
comunitat-uji-handle2:10234/7053
comunitat-uji-handle3:10234/8639
comunitat-uji-handle4:
INVESTIGACIONEste recurso está restringido
http://dx.doi.org/10.1002/chem.201103193 |
Metadatos
Título
Molecular Hydrogels from Bolaform Amino Acid Derivatives: A Structure–Properties Study Based on the Thermodynamics of Gel SolubilizationAutoría
Fecha de publicación
2012-03Editor
WileyTipo de documento
info:eu-repo/semantics/articleVersión de la editorial
http://onlinelibrary.wiley.com/doi/10.1002/chem.201103193/fullPalabras clave / Materias
Resumen
Insight is provided into the aggregation thermodynamics associated to hydrogel formation by molecular gelators derived from L-valine and L-isoleucine. Solubility data from NMR measurements are used to extract thermo ... [+]
Insight is provided into the aggregation thermodynamics associated to hydrogel formation by molecular gelators derived from L-valine and L-isoleucine. Solubility data from NMR measurements are used to extract thermodynamic parameters for the aggregation in water. It is concluded that at room temperature and up to 55 °C, these systems form self-assembled fibrillar networks in water with quite low or zero enthalpic component, whereas the entropy of the aggregation is favorable. These results are explained by considering that the hydrophobic effect is dominant in the self-assembly. However, studies by NMR and IR spectroscopy reveal that intermolecular hydrogen bonding is also a key issue in the aggregation process of these molecules in water. The low enthalpy values measured for the self-assembly process are ascribed to the result of a compensation of the favorable intermolecular hydrogen-bond formation and the unfavorable enthalpy component of the hydrophobic effect. Additionally, it is shown that by using the hydrophobic character as a design parameter, enthalpy-controlled hydrogel formation, as opposed to entropy-controlled hydrogel formation, can be achieved in water if the gelator is polar enough. It is noteworthy that these two types of hydrogels, enthalpy-versus entropy-driven hydrogels, present quite different response to temperature changes in properties such as the minimum gelator concentration (mgc) or the rheological moduli. Finally, the presence of a polymorphic transition in a hydrogel upon heating above 70 °C is reported and ascribed to the weakening of the hydrophobic effect upon heating. The new soft polymorphic materials present dramatically different solubility and rheological properties. Altogether these results are aimed to contribute to the rational design of molecular hydrogelators, which could be used for the tailored preparation of this type of soft materials. The reported results could also provide ground for the rationale of different self-assembly processes in aqueous media. [-]
Publicado en
Chemistry - A European Journal, 2012, Vol. 18, num. 13Derechos de acceso
Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
http://rightsstatements.org/vocab/InC/1.0/
info:eu-repo/semantics/restrictedAccess
http://rightsstatements.org/vocab/InC/1.0/
info:eu-repo/semantics/restrictedAccess
Aparece en las colecciones
- QUIO_Articles [692]