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Transiciones de fase sin difusión reversibles en superredes de nanopartículas 3D
Daryl W Yee1, Margaret S Lee1, Joyce An1
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|March 10, 2023
Resumen
Las nanopartículas poliméricas injertadas con pincel forman superredes ordenadas. Los investigadores descubrieron una transición de fase reversible entre las estructuras cúbicas centradas en la cara y las estructuras cúbicas centradas en el cuerpo, lo que permite el control de la microestructura.
Área de la Ciencia:
- Ciencias de los materiales
- Nanotecnología
- La cristalografía
Sus antecedentes:
- Los tectones nanocompuestos (NCTs) son nanopartículas poliméricas injertadas con pincel que se autoensamblan en superredes de nanopartículas ordenadas (NPSL) a través de interacciones supramoleculares.
- El recocido térmico generalmente conduce a simetrías de células unitarias bien definidas en NPSL.
Objetivo del estudio:
- Demostrar el control de la microestructura de la red NCT equilibrando los factores entálpicos y entrópicos durante la cristalización.
- Investigar el comportamiento de transición de fase de los TNC en respuesta a los cambios inducidos por el disolvente en la conformación del pincel de polímero.
Principales métodos:
- Ensamblaje de sistemas NCT unarios que utilizan moléculas pequeñas para mediar enlaces supramoleculares.
- Inducción de transiciones de fase mediante la transferencia de celosías FCC a disolventes que causan el colapso del pincel de polímero.
- Caracterización de las características microstruturales, incluido el hermanamiento de transformación.
Principales resultados:
- Las NCT forman inicialmente redes cúbicas centradas en la cara (FCC) en disolventes favorables.
- Una transición de fase reversible y sin difusión de FCC a celosías cúbicas centradas en el cuerpo (BCC) se produce al transferirse a un disolvente colapsado.
- Las superredes BCC exhiben gemelado de transformación, similar a las aleaciones martensíticas, mientras conservan el hábito de cristal FCC.
Conclusiones:
- El control de la microestructura de NPSL se puede lograr manipulando las condiciones de ensamblaje y procesamiento.
- La transformación de fase sin difusión observada ofrece un nuevo mecanismo para crear microestructuras únicas en ensamblajes de nanopartículas.
- Las NPSL pueden servir como sistemas modelo para el estudio de la evolución de las microestructuras y como análogos para los materiales cristalinos atómicos.
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