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Nuevos complejos de titanio de fenoxicetimina: combinan isotacticidad y comportamiento vivo en la polimerización del
Andrew F Mason1, Geoffrey W Coates
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
Journal of the American Chemical Society
|December 17, 2004
Resumen
Nuevos catalizadores de titanio permiten la polimerización viva del propileno, produciendo polipropileno isotáctico con pesos moleculares controlados. Este avance permite la creación de copolímeros de bloque avanzados para diversas aplicaciones.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La ciencia de los polímeros es la ciencia de los polímeros.
- La catálisis de la catálisis.
Sus antecedentes:
- La polimerización de las olefinas es crucial para producir plásticos.
- Los catalizadores a base de titanio son ampliamente estudiados para la polimerización de olefinas.
- Lograr la polimerización viva es clave para las arquitecturas de polímeros controlados.
Objetivo del estudio:
- Para sintetizar y evaluar nuevos catalizadores de titanio bis ((phenoxyketimine) para la polimerización del propileno.
- Para investigar el efecto de la estructura del ligando en el rendimiento del catalizador y las propiedades del polímero.
- Para demostrar las capacidades de polimerización viva de estos sistemas.
Principales métodos:
- Síntesis de complejos de titanio bis ((phenoxyketimine) con varios sustituyentes de ortofenol.
- Cribado de catalizadores para la polimerización del propileno.
- Caracterización del polipropileno utilizando técnicas para determinar la táctica y la distribución del peso molecular.
- Síntesis de copolímeros de bloque para confirmar la polimerización en vivo.
Principales resultados:
- Los catalizadores con sustitutos ortofenólicos de tamaño intermedio exhibieron un comportamiento de polimerización viva.
- Se produjo polipropileno sustancialmente isotáctico.
- Se lograron estrechas distribuciones de peso molecular, lo que indica una polimerización controlada.
- La síntesis exitosa de copolímeros de bloque confirmó la naturaleza viva de los catalizadores.
Conclusiones:
- Los catalizadores de titanio bis ((phenoxyketimine) con diseños específicos de ligandos permiten la polimerización estereoselectiva de propileno vivo.
- El bulto estérico de los sustituyentes de ortofenol es crítico para lograr las características de vida.
- Estos sistemas ofrecen una ruta prometedora para sintetizar copolímeros de bloque bien definidos basados en polipropileno.
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