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Relajación estructural de vidrios de polímero en las superficies, interfaces y en el medio
Rodney D Priestley1, Christopher J Ellison, Linda J Broadbelt
1Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
Science (New York, N.Y.)
|July 16, 2005
Resumen
La relajación estructural del polímero se ralentiza significativamente cerca de las superficies e interfaces. Este efecto se extiende a más de 100 nm en películas de polímero, impactando las propiedades del material.
Área de la Ciencia:
- La ciencia de los polímeros es la ciencia de los polímeros.
- Ciencia de los materiales Ciencia de los materiales.
- Química Física es la química física.
Sus antecedentes:
- Comprender la dinámica de los polímeros cerca de las interfaces es crucial para el diseño de materiales.
- La relajación estructural del estado vítreo gobierna el rendimiento del polímero a largo plazo.
- Los efectos de la superficie y la interfaz pueden alterar las propiedades del polímero a granel.
Objetivo del estudio:
- Para cuantificar el impacto de las superficies e interfaces en la relajación estructural del polímero.
- Para determinar la extensión espacial de estos efectos dentro de las películas de polímero.
Principales métodos:
- Utilizó el monitoreo de fluorescencia en películas poliméricas multicapa.
- Se analizaron las tasas de relajación estructural del polimetil metacrilato (PMMA).
- Comparación de las tasas de relajación en superficies libres e interfaces de sílice con PMMA a granel.
Principales resultados:
- La tasa de relajación estructural se reduce 2 veces en las superficies libres y 15 veces en las interfaces de sílice.
- Se observó una detención casi completa de la relajación en la interfaz de sílice.
- Se observó una relajación lenta hasta 100 nm en la película de polímero.
Conclusiones:
- Las superficies e interfaces ralentizan drásticamente la relajación estructural del polímero.
- Estos efectos penetran más profundamente en el polímero que los cambios en la temperatura de transición de vidrio.
- Los cambios inducidos por la interfaz en la dinámica de los polímeros son significativos y de largo alcance.
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