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Numerical evidences for a free energy barrier in starlike polymer brushes
- Source :
- The Journal of Chemical Physics. 139:134910
- Publication Year :
- 2013
- Publisher :
- AIP Publishing, 2013.
-
Abstract
- The existence of a free energy barrier, which prohibits the upward motion of retracted molecules into the surface region of starlike polymer brushes, is analyzed through molecular dynamics simulations in good solvent. This barrier emerges at moderate and high grafting densities, as a result of a density-discontinuity at the branching points of the highly stretched starlike molecules. The vertical force profiles of brushes of varying densities are taken with the help of a probe-particle that is gradually moved into the brush, and the results are compared with the density profiles and their negative gradients which generate the local osmotic pressures. Chain expulsion simulations, supported by scaling theory, are conducted to understand the dynamics of individual molecules inside the brushes. We prove that the flip-rates between retracted and extended states, being of relevance for the generation of efficiently switchable, environment-responsive brush layers, are determined by the elastic tension of the stretched molecules.
- Subjects :
- chemistry.chemical_classification
Quantitative Biology::Biomolecules
General Physics and Astronomy
Brush
Branching points
Polymer
Scaling theory
law.invention
Condensed Matter::Soft Condensed Matter
Molecular dynamics
chemistry
Chemical physics
Computational chemistry
law
Molecule
Polymer blend
Physical and Theoretical Chemistry
Elasticity (economics)
Subjects
Details
- ISSN :
- 10897690 and 00219606
- Volume :
- 139
- Database :
- OpenAIRE
- Journal :
- The Journal of Chemical Physics
- Accession number :
- edsair.doi.dedup.....c026cabd904027b1764b3a738b5d85d7