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Una transición reversible de tubo a vara en una micella de copolímero de bloque

Jose Raez¹, Juan Pablo Tomba, Ian Manners

¹Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.

Journal of the American Chemical Society

|August 9, 2003

Resumen

Los cambios de temperatura inducen una transformación reversible en los copolímeros diblock de poli (ferrocenilidimetilesilano-b-dimetilsiloxano), cambiando de los nanotubos a las barras y viceversa. Esto pone de relieve la naturaleza dinámica de estas estructuras poliméricas de equilibrio.

Área de la Ciencia:

La ciencia de los polímeros es la ciencia de los polímeros.
Ciencia de los materiales Ciencia de los materiales.
Química Física es la química física.

Sus antecedentes:

Los copolímeros Diblock exhiben un comportamiento complejo de autoensamblaje en solución.
La temperatura es un parámetro crítico que influye en la morfología del polímero y las transiciones de fase.

Objetivo del estudio:

Para investigar las transiciones morfológicas dependientes de la temperatura de un copolímero diblock específico: poli ((ferrocenyldimethylsilane-b-dimethylsiloxane) (PFS40-b-PDMS480).
Para caracterizar las propiedades estructurales de las diferentes morfologías formadas.
Para determinar si estas morfologías representan estados de equilibrio.

Principales métodos:

Preparación de la solución del copolímero diblock en n-decane.
Experimentos de variación de temperatura (25°C a 50°C y viceversa).
Mediciones de la dispersión estática de la luz (SLS).
Microscopía electrónica (implicado para la comparación).

Principales resultados:

El copolímero diblock se autoensambla en nanotubos a 25°C.
Al calentar a 50°C, la morfología cambia a varillas cortas y densas.
El enfriamiento de nuevo a 25°C invierte la transición, reformando los nanotubos.
SLS confirmó el núcleo rígido e insoluble de poli (ferrocenilidimetilsilano) en las estructuras de las barras.

Conclusiones:

Las estructuras de nanotubos y varillas observadas son dinámicas y representan estados de equilibrio.
La temperatura es un factor clave que controla la morfología de autoensamblaje de este copolímero diblock.
El bloque de poli (ferrocenilidimetilsilano) forma un núcleo rígido dentro de las estructuras ensambladas.

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