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Catálisis bimetálica para la homopolimización del estireno y la copolimización de etileno-estireno. Selectividad

Neng Guo¹, Liting Li, Tobin J Marks

¹Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.

Journal of the American Chemical Society

|May 27, 2004

Resumen

Un nuevo catalizador bimetálico (Ti2) demuestra una alta actividad en la homopolimización del estireno y una eficiente copolimización de etileno-estireno. Este catalizador de un solo sitio permite un amplio control de la composición del estireno en copolímeros.

Área de la Ciencia:

Química de Polímeros La Química de Polímeros es la química de los polímeros.
Química organometálica Química orgánica de los metales.
La catálisis es la catálisis.

Sus antecedentes:

Los catalizadores de geometría restringida (CGC) son cruciales en la polimerización de las olefinas.
La estructura del catalizador de afinación puede afectar significativamente el comportamiento de polimerización y las propiedades del polímero.

Objetivo del estudio:

Para investigar la homopolimización de estireno y la copolimización de etileno-estireno de un nuevo catalizador bimetálico de geometría constreñida (Ti2).
Para comparar el rendimiento de Ti2 con su análogo mononuclear (Ti1).

Principales métodos:

Síntesis y caracterización del catalizador bimetálico Ti2.
Experimentos de homopolimerización del estireno y de copolimerización de etileno y estireno.
13C espectroscopia de RMN para el análisis de microestructuras.
Análisis del grupo final para la investigación de la etapa de inicio.

Principales resultados:

Ti2 exhibe una actividad significativamente más alta (50 veces) en la homopolimerización del estireno en comparación con Ti1.
Ti2 logra una eficiente copolimerización de etileno-estireno en un amplio rango de composición de estireno (0-76%).
El copolímero producido por Ti2 muestra secuencias de estireno encadenadas de más de dos unidades de longitud.
La homopolimerización del estireno con Ti2 muestra aproximadamente un 50% de 1,2-regiocímica en las etapas iniciales.

Conclusiones:

La estructura bimetálica del Ti2 es responsable de su mayor actividad catalítica y su único control de la microestructura.
Ti2 representa un gran avance en la catálisis de un solo sitio tanto para la homopolimerización del estireno como para la copolimización de etileno-estireno.
Este catalizador ofrece un control preciso sobre la composición y la microestructura del copolímero, abriendo nuevas vías para el diseño de polímeros.

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