Video Experimental Relacionado
Updated: Feb 2, 2026
09:02
Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization
Published on: July 9, 2015
12.8K
Dendronizado Poly ((2-oxazolina) Se muestra dentro de las unidades de repetición de cinco monómeros Casicristal
Marian N Holerca1, Dipankar Sahoo1, Benjamin E Partridge1
1Roy & Diana Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States.
Journal of the American Chemical Society
|November 22, 2018
Resumen
Los investigadores sintetizaron una nueva poli-oxalina que se autoorganiza en cuasicristales líquidos (LQC) y dos fases de Frank-Kasper. Este descubrimiento ofrece un sistema modelo para estudiar la autoorganización de la materia blanda en matrices periódicas y cuasi periódicas complejas.
Área de la Ciencia:
- Física de la materia blanda
- Ciencias de los materiales
- Química de los polímeros
Sus antecedentes:
- Los cuasicristales líquidos (LQC) y las fases de Frank-Kasper (Pm3̅n cúbico y P42/mnm tetragonal) son estructuras autoensambladas complejas que se encuentran en varios sistemas de materia blanda.
- Estudios previos identificaron estas fases en los dendrones y los copolímeros de bloque, pero no en las poli-oxázolinas.
- Se sabía que las poli ((2-oxazolinas) dendronizadas con cadenas de alquilo más cortas (n=14-16) formaban las fases de Frank-Kasper.
Objetivo del estudio:
- Síntesis y caracterización de una poli-oxazolina dendronizada capaz de formar LQC.
- Investigar el comportamiento de autoensamblaje de las poli-oxalinas con diferentes grados de polimerización (DP).
- Para explorar la formación de las fases LQC y Frank-Kasper de un solo sistema de polímero.
Principales métodos:
- Síntesis de una poli-oxazolina dendronizada con n=17 cadenas de alquilo.
- Análisis estructural y retrostructural de las fases autoensambladas.
- Observación del comportamiento de la fase dentro de un rango estrecho de DP (5 ≤ DP ≤ 10).
Principales resultados:
- Se sintetizó y se autoorganizó en fases tetragonales LQC, Pm3̅n cúbico y P42/mnm.
- Se observaron las tres fases distintas del mismo polímero dentro de un rango estrecho de DP (5 ≤ DP ≤ 10).
- Esta es la primera instancia reportada de formación de LQC en un sistema poli-oxázolino.
Conclusiones:
- Una sola cadena de poli{2-oxazolina} puede autoorganizarse en estructuras periódicas y cuasi periódicas (LQC, fases de Frank-Kasper) dentro de un rango limitado de DP.
- Los hallazgos plantean preguntas fundamentales sobre los mecanismos que impulsan la autoorganización en estos conjuntos complejos.
- Este sistema sirve como un modelo valioso para los estudios teóricos sobre el autoensamblaje de materia blanda en Frank-Kasper y estructuras relacionadas.
Más Videos Relacionados
Videos de Conceptos Relacionados
02:31Phase Transitions
23.2K
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...
23.2K
03:38Measurement: Standard Units
79.8K
Every measurement provides three kinds of information: the size or magnitude of the measurement (a number), a standard of comparison for the measurement (a unit), and an indication of the uncertainty of the measurement. While the number and unit are explicitly represented when a quantity is written, the uncertainty is an aspect of the errors in the measurement results.
79.8K
03:02Measurement: Derived Units
55.4K
The International System of Units or SI system, by international agreement, has fixed measurement units for seven fundamental properties: length, mass, time, temperature, electric current, amount of substance, and luminosity. These are called the SI base units.
55.4K
02:39Phase Diagrams
50.2K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
50.2K
02:33Phase Transitions: Sublimation and Deposition
20.2K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
20.2K
01:27Units of Measurement
5.2K
Mechanical engineering is one of the oldest branches of engineering. It deals with designing, analyzing, and manufacturing machines and mechanical systems. To ensure precise and accurate calculations, units of measurement are used. They provide a standard system for expressing and comparing physical quantities.
There are various well-known historical measurement systems, such as the Babylonian system, the Roman system, the Egyptian system, the Olympian system, the British system, and the Indus...
There are various well-known historical measurement systems, such as the Babylonian system, the Roman system, the Egyptian system, the Olympian system, the British system, and the Indus...
5.2K