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Toda la miscibilidad de los mesógenos en forma de disco y vara en la fase nemática
Paul H J Kouwer1, Georg H Mehl
1Department of Chemistry, University of Hull, Cottingham Road, Hull, HU6 7RX, UK.
Journal of the American Chemical Society
|October 14, 2005
Resumen
Los mesógenos con formas mixtas de barra y disco muestran fases de cristal líquido nemático y se mezclan bien con otros tipos. Una nueva fase nemática surge en proporciones específicas, alineándose con las predicciones del comportamiento nemático biaxial.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Química Física es la química física.
- Física de los cristales líquidos Física de los cristales líquidos
Sus antecedentes:
- Los cristales líquidos (LC) exhiben fases entre el líquido sólido y el líquido isotrópico.
- Las moléculas en forma de vara y en forma de disco forman distintas mesofasas.
- La forma molecular influye en el comportamiento de la fase LC y la miscibilidad.
Objetivo del estudio:
- Para investigar las propiedades cristalinas líquidas de las moléculas que combinan unidades estructurales en forma de vara y disco.
- Para explorar la miscibilidad de estos mesógenos híbridos con los mesógenos convencionales en forma de vara y disco.
- Para caracterizar el comportamiento de la fase e identificar nuevas fases nemáticas.
Principales métodos:
- Síntesis de mezógenos híbridos de barra y disco.
- Calorimetría de barrido diferencial (DSC) para el análisis de la transición de fase.
- Microscopía óptica polarizada (POM) para la identificación de fase.
- Construcción del diagrama de fases para mezclas binarias.
Principales resultados:
- Los mesógenos híbridos de barra y disco exhiben un comportamiento de fase nemática.
- Se observó una miscibilidad completa entre los mesógenos híbridos y los mesógenos en forma de vara y disco en la fase nemática.
- Se identificó una fase nemática adicional en el diagrama de fase en relaciones casi equimolares disco-vara.
Conclusiones:
- Las moléculas con porciones mixtas de barra y disco son compatibles con los mesógenos convencionales en la fase nemática.
- La miscibilidad apoya la formación de complejos sistemas de cristales líquidos.
- El descubrimiento de una fase nemática adicional en composiciones específicas proporciona evidencia experimental para las fases biaxiales nemáticas predichas.
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