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Ordenamiento nemático dependiente de la longitud de la cadena de los polímeros conjugados en un solvente de cristales
Alexei Tcherniak1, David Solis, Saumyakanti Khatua
1Department of Chemistry, Rice University, Houston, Texas 77005, USA.
Journal of the American Chemical Society
|August 20, 2008
Resumen
El parámetro de orden de los polímeros en cristales líquidos disminuye con el aumento del peso molecular. Las cadenas de polímeros más grandes tienen más defectos, lo que limita su alineación dentro del disolvente cristalino líquido.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- La ciencia de los polímeros es la ciencia de los polímeros.
- Química Física es la química física.
Sus antecedentes:
- Los cristales líquidos son fluidos anisotrópicos con propiedades ópticas y eléctricas únicas.
- Los solutos poliméricos pueden influir y alinearse con las fases cristalinas líquidas.
- Comprender las interacciones soluto-solvente es crucial para el desarrollo de materiales avanzados.
Objetivo del estudio:
- Para investigar la relación entre el peso molecular del polímero y su parámetro de orden en un disolvente cristalino líquido.
- Para cuantificar la alineación de poli[2-metoxi-5-(2'-etil-hexiloxi) -1,4-fenileno vinileno] (MEH-PPV) en el 4-ciano-4-n-pentilbifenilo (5CB).
Principales métodos:
- Se utilizó la espectroscopia de polarización por absorción de conjunto.
- Se emplearon mediciones de polarización por fluorescencia de una sola molécula.
- Determinado el parámetro de orden de MEH-PPV en función de la longitud de la cadena de polímero en 5CB.
Principales resultados:
- Demostró una clara dependencia del parámetro de orden del soluto en el peso molecular del soluto.
- Se observó un ordenamiento a gran escala de MEH-PPV dentro del cristal líquido 5CB.
- Encontró una buena concordancia entre las técnicas espectroscópicas de conjunto y de molécula única.
Conclusiones:
- El aumento del peso molecular del polímero conduce a un mayor número de defectos.
- Estos defectos limitan intrínsecamente el grado de alineación para solutos de polímeros más grandes.
- Los hallazgos proporcionan información sobre el comportamiento del polímero en medios cristalinos líquidos.
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