Related Experiment Video
Updated: May 6, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
11.5K
Cooperativity length scale in nanocomposites: interfacial and confinement effects
A Saiter1, D Prevosto, E Passaglia
1AMME-LECAP EA4528 International Laboratory, Institut des Matériaux de Rouen, Université et INSA de Rouen, BP12, 76801 Saint Etienne du Rouvray Cedex, France.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 16, 2013
Summary
Interfacial and confinement effects influence polymer dynamics near the glass transition. Confinement significantly reduces cooperativity and glass transition temperature in nanocomposites, while interfacial effects show minimal impact.
Area of Science:
- Materials Science
- Polymer Physics
- Nanotechnology
Background:
- Understanding polymer behavior near the glass transition is crucial for material design.
- Interfacial and confinement effects in polymer nanocomposites can significantly alter material properties.
- Cooperativity and fragility are key parameters describing the dynamics of glass-forming materials.
Purpose of the Study:
- To investigate the impact of interfacial and confinement effects on polymer dynamics.
- To study the evolution of cooperativity and relaxation dynamics approaching the glass transition.
- To analyze these effects in poly(propylenecoethylene) and polyethylene 1,4-cyclohexylenedimethylene terephthalate glycol nanocomposites.
Main Methods:
- Studied polymer nanocomposites with montmorillonite.
- Analyzed interfacial and confinement effects on cooperativity and relaxation dynamics.
- Investigated the temperature dependence of generalized fragility and cooperativity.
Main Results:
- Interfacial interactions in poly(propylenecoethylene) nanocomposites showed minor effects on cooperativity and glass transition temperature.
- Confinement in polyethylene 1,4-cyclohexylenedimethylene terephthalate glycol nanocomposites led to reduced cooperativity, altered relaxation frequency dependence, and lowered glass transition temperature.
- Fragility of glass formers is influenced by factors beyond just cooperativity.
Conclusions:
- Interfacial effects have a limited impact on polymer dynamics near the glass transition.
- Confinement within nanocomposite galleries significantly modifies polymer chain dynamics and thermal properties.
- Fragility is a complex property not solely dictated by cooperativity.
Related Concept Videos
01:27¹H NMR: Long-Range Coupling
2.4K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.4K
01:58Cooperative Allosteric Transitions
7.4K
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...
7.4K
01:09Theories of Dissolution: The Danckwerts' Model and Interfacial Barrier Model
938
Various dissolution theories provide insight into the factors that influence the dissolution rate. Danckwerts' Model suggests that turbulence, rather than a stagnant layer, characterizes the dissolution medium at the solid-liquid interface. In this model, the agitated solvent contains macroscopic packets that move to the interface via eddy currents, facilitating the absorption and delivery of the drug to the bulk solution. The regular replenishment of solvent packets maintains the...
938
02:35Noncovalent Attractions in Biomolecules
28.0K
Noncovalent attractions are associations within and between molecules that influence the shape and structural stability of complexes. These interactions differ from covalent bonding in that they do not involve sharing of electrons.
Four types of noncovalent interactions are hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic interactions.
Hydrogen bonding results from the electrostatic attraction of a hydrogen atom covalently bonded to a strong-electronegative atom like oxygen,...
Four types of noncovalent interactions are hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic interactions.
Hydrogen bonding results from the electrostatic attraction of a hydrogen atom covalently bonded to a strong-electronegative atom like oxygen,...
28.0K
02:35Noncovalent Attractions in Biomolecules
19.9K
19.9K
01:23Factors Affecting Dissolution: Particle Size and Effective Surface Area
1.9K
Dissolution kinetics, an essential aspect of oral drug delivery, is significantly influenced by the drug's particle size. According to the Noyes-Whitney dissolution model, the dissolution rate correlates directly with the drug's surface area. The larger the surface area, the higher the drug's solubility in water, leading to a faster drug dissolution rate. Reducing particle size increases the effective surface area, enhancing the dissolution process. Micronization and nanosizing are...
1.9K