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Cadenas de vesículas: comportamiento de flujo en un tipo inusual de gel acuoso
Fredric M Menger1, Andrey V Peresypkin
1Department of Chemistry, Emory University, 1515 Pierce Drive, Atlanta, Georgia 30322, USA. menger@emory.edu
Journal of the American Chemical Society
|May 2, 2003
Resumen
Diez surfactantes gemini asimétricos se autoensamblan en vesículas cohesivas, formando geles que rigidifican el agua. La gelación es mecánicamente reversible y sensible a la estructura de los tensioactivos, con aplicaciones potenciales.
Área de la Ciencia:
- Química supramolecular de las moléculas.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los surfactantes asimétricos se autoensamblan en estructuras complejas.
- La formación de vesículas y la posterior gelación son fenómenos clave en la química de los tensioactivos.
Objetivo del estudio:
- Investigar el autoensamblaje de surfactantes asimétricos gemini en vesículas y geles.
- Comprender los factores que influyen en la cohesión vesicular y la formación de gel.
- Explorar las propiedades mecánicas y la reversibilidad de los geles resultantes.
Principales métodos:
- Dispersión dinámica de la luz (DLS) para el análisis del tamaño de las vesículas.
- Microscopía electrónica de transmisión (TEM) y microscopía electrónica de barrido de alta resolución (cryo-HRSEM) para estudios de morfología.
- Experimentos reológicos para evaluar las propiedades del gel y la reversibilidad mecánica.
Principales resultados:
- Los surfactantes asimétricos gemini se autoensamblan en vesículas en soluciones acuosas diluidas.
- Las vesículas forman estructuras cohesivas de "perlas en una cuerda", que conducen a la gelación.
- Un tensioactivo específico de Gemini no pudo formar un gel, y en su lugar se ensambló en grupos.
- La gelatación es mecánicamente reversible por encima de la temperatura de fusión del tensioactivo (T (m)).
- La fuerza del gel depende en gran medida de la estructura molecular del tensioactivo gemini.
Conclusiones:
- La protuberancia de cadenas cortas desde las superficies de las vesículas impulsa la cohesión y la formación de gel.
- La vía de autoensamblaje (cadenas frente a grupos) dicta la capacidad de gelatización.
- Los surfactantes, vesículas y geles Gemini estudiados muestran potencial para diversas aplicaciones prácticas.
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