Video Experimental Relacionado
Updated: May 5, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 21, 2014
11.5K
Las transiciones de fase de los cristales líquidos en suspensiones de partículas polidispersas parecidas a placas
van der Kooij FM1, Kassapidou, Lekkerkerker
1Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, The Netherlands.
Nature
|September 6, 2000
Resumen
Los coloides tipo placa forman fases de cristal líquido, incluido un cristal bidimensional columnar estable, incluso con una polydispersidad significativa. Este hallazgo simplifica el logro del orden cristalino líquido en materiales mesoscópicos sintéticos.
Área de la Ciencia:
- Ciencia de los materiales Ciencia de los materiales.
- Física de la materia blanda Física de la materia blanda
- Ciencia de la coloide Ciencia de las coloides.
Sus antecedentes:
- Las suspensiones coloidales con estructuras de autoensamblaje son tecnológicamente relevantes, especialmente para los materiales fotónicos.
- Las partículas coloidales no esféricas, como las barras y las placas, pueden formar cristales líquidos con orden de orientación y posición.
- La polidispersidad (variación en el tamaño de las partículas) puede dificultar el ordenamiento posicional en las suspensiones coloidales.
Objetivo del estudio:
- Para investigar el comportamiento de la fase cristalina líquida de las suspensiones coloidales tipo placa.
- Para determinar la influencia de la concentración de partículas y la polidispersidad en el autoensamblaje.
- Para evaluar la estabilidad de las fases ordenadas en sistemas polidispersos.
Principales métodos:
- Preparación y caracterización de suspensiones coloidales tipo placa.
- Variación sistemática de la concentración de partículas.
- Observación de las transiciones de fase (isotrópica, nemática, columnar) a través de la microscopía o técnicas de dispersión.
- Análisis del orden estructural y los efectos de polidispersidad.
Principales resultados:
- Una suspensión de coloides tipo placa exhibió fases isotrópicas, nemáticas y columnares con una concentración creciente.
- La fase de cristal columnar bidimensional se mantuvo estable para la polidispersidad hasta un 25%.
- Se observó una transición al ordenamiento semejante a un esmético en concentraciones muy altas de partículas.
Conclusiones:
- El orden cristalino líquido en materiales mesoscópicos sintéticos puede ser más fácil de lograr de lo que se anticipó anteriormente.
- Los coloides tipo placa ofrecen una ruta prometedora para crear estructuras ordenadas con propiedades sintonizables.
- La robustez de la fase columnar a la polidispersidad es un hallazgo significativo para el diseño de materiales.
Videos de Conceptos Relacionados
02:31Phase Transitions
19.1K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
19.1K
03:22Colloids
17.2K
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
17.2K
01:21Polymer Classification: Crystallinity
3.1K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
3.1K
01:17Colloids and Suspensions
3.4K
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
3.4K
01:09Colloidal precipitates
5.7K
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
5.7K
01:29The Colloidal State
189
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called...
189