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Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers
Published on: December 16, 2022
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Síntesis de polímeros de cepillo de botella por polimerización de metástasis de apertura de anillo vivo específico,
Sirilak Mekcham1, Kotohiro Nomura1
1Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami Osawa, Hachioji, Tokyo 192-0397, Japan.
Journal of the American Chemical Society
|July 27, 2023
Resumen
Los nuevos catalizadores de vanadio permiten la síntesis selectiva Z o E de polímeros de brocha de botella (BBPs) y bloquean los copolímeros a través de la polimerización de metástasis de apertura de anillo vivo. Estos polímeros exhiben propiedades distintas basadas en su estereoquímica y cristalización de la cadena lateral.
Área de la Ciencia:
- Química de los polímeros
- Química organometálica
- Ciencias de los materiales
Sus antecedentes:
- Los polímeros de pincel de botella (BBPs) y los copolímeros de bloque son arquitecturas poliméricas avanzadas con propiedades ajustables.
- La polimerización de metástasis de apertura de anillo vivo (ROMP) es una técnica poderosa para la síntesis controlada de polímeros.
- El control de la estereoquímica (selectividad Z/E) durante la ROMP es crucial para adaptar las propiedades del polímero.
Objetivo del estudio:
- Para sintetizar polímeros de pincel selectivo Z y E (BBPs) y copolímeros de bloque.
- Investigar el uso de catalizadores específicos de vanadio (V) - alquilideno para la ROMP estereoselectiva.
- Para explorar la influencia de la estereoquímica del polímero en las propiedades del material como la temperatura de fusión.
Principales métodos:
- Polimerización por metástasis de apertura de anillo vivo (ROMP) de N-substituido-norborneno-2,3-dicarboxímidos con cadenas de alquilo largas.
- Los catalizadores de vanadio (((V) -alquilideno utilizados son: V ((CHSiMe3) ((ArN) ((OC ((CF3))) ((PMe3) 2) para la selectividad Z y V ((CHSiMe3) ((2,6-F2C6H3N) ((OC6Cl5))) para la selectividad E.
- Caracterización de la estereoquímica del polímero (razón Z/E) y de las propiedades térmicas (temperatura de fusión).
Principales resultados:
- El catalizador 1 logró una selectividad Z exclusiva (>99% cis) para la síntesis de BBP, incluso a temperaturas elevadas (80 °C).
- El catalizador 3 produjo BBPs con alta selectividad E (90% trans).
- Ambos catalizadores demostraron un comportamiento de polimerización vivo, lo que permite la síntesis de copolímeros de bloque anfifílico con estereoquímica controlada y temperaturas de fusión distintas debido a la cristalización de la cadena lateral.
Conclusiones:
- Los catalizadores de vanadio proporcionan un control preciso de la estereoselectividad Z/E en la ROMP de los dicarboxímidos de norborneno.
- Los BBPs Z- y E-selectivos sintetizados, particularmente aquellos con cadenas laterales n-octadecilo, exhiben diferentes puntos de fusión.
- Este control estereoquímico y las interacciones de cadena lateral resultantes ofrecen una vía para diseñar polímeros con propiedades térmicas a medida.
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