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La nucleación de hielo por alcoholes dispuestos en monocapas en la superficie de las gotas de agua
Science (New York, N.Y.)
|November 16, 1990
Resumen
Los alcoholes alifáticos de cadena larga, a diferencia de los agentes anticongelantes, inducen la nucleación del hielo cerca de 0 °C. Su punto de congelación depende de la longitud de la cadena y la paridad, formando grupos ordenados que coinciden con las estructuras de hielo hexagonales.
Área de la Ciencia:
- Química Física es la química física.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los alcoholes solubles en agua actúan como agentes anticongelantes.
- No se comprende completamente la interacción de los alcoholes anfifílicos con el agua y la formación de hielo.
Objetivo del estudio:
- Para investigar las propiedades de nucleación de hielo de los alcoholes alifáticos de cadena larga.
- Para explorar la influencia de la estructura molecular en la temperatura de formación de hielo.
Principales métodos:
- Formación de monocapas de alcohol en las superficies del agua.
- Medición de las temperaturas de nucleación del hielo.
- Difracción de rayos X de sincrotrón de incidencia de pastoreo para analizar la estructura molecular.
Principales resultados:
- Los alcoholes alifáticos nuclearon el hielo cerca de 0 °C, en contraste con las propiedades anticongelantes de los alcoholes solubles en agua.
- Se observó una depresión del punto de congelación de hasta 12 °C para los ácidos grasos y los alcoholes con grupos hidrofóbicos voluminosos.
- La temperatura de nucleación del hielo es sensible al área de la superficie molecular, la longitud de la cadena y la paridad (par / impar) para los alcoholes alifáticos.
- Formación de racimos ordenados detectados en monocapas de alcohol alifático, con hielo hexagonal que coincide con la celosía.
Conclusiones:
- Los alcoholes alifáticos de cadena larga promueven la nucleación del hielo en lugar de actuar como agentes anticongelantes.
- La estructura molecular, específicamente la longitud de la cadena y la paridad, tiene un impacto significativo en la temperatura de nucleación de hielo de estos alcoholes.
- Los grupos ordenados formados por estos alcoholes juegan un papel crucial en la nucleación del hielo, mostrando compatibilidad estructural con el hielo hexagonal.
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