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Los cambios inducidos térmicamente en la anfifilicidad impulsan la reestructuración reversible de conjuntos de

Yu Cai¹, Katherine B Aubrecht, Robert B Grubbs

¹Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States.

Journal of the American Chemical Society

|December 25, 2010

Resumen

Los copolímeros termorresponsivos poli (óxido de etileno) -b-poli (óxido de etileno) -stat-óxido de butileno) -b-poli (isopreno) (E-BE-I) se transforman de micelas esféricas a vesículas con el aumento de la temperatura. Esta rápida reorganización es más rápida que otros sistemas, lo que sugiere un papel para el enlace de hidrógeno en la cinética.

Área de la Ciencia:

Química de Polímeros La Química de Polímeros es la química de los polímeros.
Ciencia de los materiales Ciencia de los materiales.
Química supramolecular de las moléculas.

Sus antecedentes:

Los copolímeros de tribloque ABC con un bloque medio sensible al estímulo pueden cambiar entre ensamblajes estables.
Los polímeros termorresponsivos son clave para los materiales avanzados y la administración de medicamentos.

Objetivo del estudio:

Para sintetizar y caracterizar nuevos copolímeros termorresponsivos poli (óxido de etileno) -b-poli (óxido de etileno) -stat-óxido de butileno) -b-poli (isopreno) (E-BE-I) tribloqueados.
Investigar las transiciones de ensamblaje inducidas por la temperatura de estos copolímeros E-BE-I desde micelas a polimerosomas.

Principales métodos:

Polimerizaciones secuenciales de radicales vivos aniónicos y mediadas por nitróxido para la síntesis de copolímero.
Dispersión dinámica de la luz (DLS) y microscopía electrónica de transmisión (TEM) para caracterizar la morfología y el tamaño de los agregados.
Mediciones de puntos de nubes para evaluar el comportamiento termorresponsivo.

Principales resultados:

Copolímeros E-BE-I tribloqueados sintetizados con distribuciones de peso molecular estrechas.
Formación observada de agregados casi esféricos a 25 °C.
Se ha demostrado la transformación inducida por la temperatura de micelas esféricas a vesículas (polímerosomas) a temperaturas elevadas.
Se encontró una cinética de transformación más rápida en comparación con los sistemas de poli (óxido de etileno) -b-poli (N-isopropilacrilamida) -b-poli (isopreno).

Conclusiones:

Los copolímeros de tribloqueo E-BE-I exhiben un autoensamblaje termoresponsivo sintonizable en micelas y polimerosomas.
La cinética de reordenamiento rápido de los agregados sugiere que el enlace de hidrógeno entre cadenas del bloque sensible es crucial.
Estos hallazgos ofrecen nuevas posibilidades para materiales sensibles a estímulos y ensamblaje controlado.

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