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Catalizadores de cobalto para la copolimización alterna de óxido de propileno y dióxido de carbono: combinación de
Claire T Cohen1, Tony Chu, Geoffrey W Coates
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
Journal of the American Chemical Society
|August 4, 2005
Resumen
Los catalizadores de cobalto altamente activos permiten una copolimización eficiente y viva del óxido de propileno y el CO2 para producir carbonato de polipropileno con microestructura controlada. Estos catalizadores ofrecen una mayor actividad y selectividad, incluso a bajas presiones de CO2.
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:
- El desarrollo de catalizadores eficientes para la utilización de CO2 es crucial para la química sostenible.
- El carbonato de polipropileno (PPC) es un polímero biodegradable con aplicaciones potenciales.
- La copolimerización viva ofrece un control preciso sobre las propiedades del polímero.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos cobalto-salina como catalizadores.
- Para investigar la vida, alternando la copolimización del óxido de propileno (PO) y el CO2.
- Explorar los efectos de la estructura del catalizador y los cocatalizadores en las propiedades del PPC.
Principales métodos:
- Síntesis de complejos (salcicos) CoX (X = haluro o carboxilato).
- Reacciones de copolimerización utilizando varios catalizadores y cocatalizadores de cobalto ([PPN]Cl, [PPN][OBzF(5)).
- Análisis de la microestructura del polímero, la distribución del peso molecular (MWD) y la actividad catalítica.
Principales resultados:
- Los complejos cobalto-saleno son catalizadores altamente activos para la vida, alternando la copolimización de PO y CO2.
- PPC producido exhibe alta regioregularidad (hasta un 99% de enlaces de carbonato) y estrecha MWD.
- Los cocatalizadores mejoran significativamente la actividad catalítica, la estereoselectividad y la regioselectividad, logrando altas frecuencias de rotación (hasta 1100 h−1).
- La estereoquímica de monómeros y catalizadores influye dramáticamente en la microestructura de PPC, lo que permite el control de la regioregularidad y el enriquecimiento sindio.
Conclusiones:
- Los nuevos catalizadores de cobalto-salinas y los sistemas de cocatalizadores proporcionan una eficiencia y un control sin precedentes en la copolimización PO/CO2.
- Este trabajo avanza en la síntesis de carbonato de polipropileno funcional con microestructuras a medida.
- Los hallazgos ofrecen una ruta prometedora para la valorización del CO2 en polímeros valiosos.
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