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Modelo de difusión cooperativa para el transporte de cargas por polímeros no conjugados redox-activos
Kan Sato1, Rieka Ichinoi1, Ryusuke Mizukami1
1Department of Applied Chemistry, Waseda University , Tokyo 169-8555, Japan.
Journal of the American Chemical Society
|December 26, 2017
Resumen
El transporte de carga en polímeros es lento debido al movimiento limitado. Un nuevo diseño de sistema supramolecular supera esto, logrando altas tasas de transferencia de carga para materiales avanzados.
Área de la Ciencia:
- La electroquímica
- Ciencia de los Polímeros
- Química de los materiales
Sus antecedentes:
- El transporte de carga en polímeros redox no conjugados es crucial para las aplicaciones de almacenamiento de energía.
- En estudios anteriores se habían observado bajas tasas de transferencia de cargas, pero carecía de una explicación cuantitativa.
- La movilidad limitada de los centros redox dentro de las cadenas de polímeros fue una causa sospechosa pero no probada.
Objetivo del estudio:
- Explicar cuantitativamente las constantes de velocidad de transferencia de carga reducida en polímeros redox activos.
- Proponer un nuevo diseño para mejorar el transporte de carga en dichos sistemas.
- Para lograr altas constantes de velocidad de transferencia de carga y densidades de sitio comparables a los sistemas de solución libre.
Principales métodos:
- Utilizó un modelo de difusión cooperativa para analizar los mecanismos de transporte de carga.
- Investigó la influencia del movimiento browniano restringido de los centros redox unidos al polímero.
- Propuso y evaluó teóricamente un sistema supramolecular redox-activo.
Principales resultados:
- Se demostró cuantitativamente una disminución de 10^3-4^ en las constantes bimoleculares y heterogéneas de la velocidad de transferencia de carga debido al movimiento browniano limitado.
- Identificó la movilidad restringida de los centros redox como la causa inexplicable de la transferencia lenta de carga.
- Diseñó un sistema supramolecular que exhibe una alta movilidad física para centros redox.
Conclusiones:
- La movilidad física limitada de los centros redox en polímeros no conjugados impide significativamente la transferencia de carga.
- Un nuevo diseño de sistema supramolecular redox-activo puede superar estas limitaciones.
- Este enfoque permite constantes de velocidad de transferencia de carga superiores a 10^7 M^-1 s^-1 con altas densidades de sitio, allanando el camino para los dispositivos electroquímicos de próxima generación.
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