Utilizad este identificador para citar o enlazar este documento: http://hdl.handle.net/2072/224144

From caging to rouse dynamics in polymer melts with intramolecular barriers: a critical test of the mode coupling theory
Bernabei, Marco; Moreno, Ángel J.; Zaccarelli, Emanuela; Sciortino, Francesco; Colmenero, Juan
By means of computer simulations and solution of the equations of the mode coupling theory (MCT),we investigate the role of the intramolecular barriers on several dynamic aspects of nonentangled polymers. The investigated dynamic range extends from the caging regime characteristic of glass-formers to the relaxation of the chain Rouse modes. We review our recent work on this question,provide new results, and critically discuss the limitations of the theory. Solutions of the MCT for the structural relaxation reproduce qualitative trends of simulations for weak and moderate barriers. However, a progressive discrepancy is revealed as the limit of stiff chains is approached. This dis-agreement does not seem related with dynamic heterogeneities, which indeed are not enhanced by increasing barrier strength. It is not connected either with the breakdown of the convolution approximation for three-point static correlations, which retains its validity for stiff chains. These findings suggest the need of an improvement of the MCT equations for polymer melts. Concerning the relaxation of the chain degrees of freedom, MCT provides a microscopic basis for time scales from chain reorientation down to the caging regime. It rationalizes, from first principles, the observed deviations from the Rouse model on increasing the barrier strength. These include anomalous scaling of relaxation times, long-time plateaux, and nonmonotonous wavelength dependence of the mode correlators.
21-02-2014
Polímers
Macromolècules
Simulació per ordinador
Teoria de jocs
Polymers
Macromolecules
Computer simulation
Game theory
(c) American Institute of Physics , 2011
Artículo
info:eu-repo/semantics/publishedVersion
American Institute of Physics
         

Mostrar el registro completo del ítem

Documentos relacionados

Otros documentos del mismo autor/a

Bernabei, Marco; Moreno, Ángel J.; Zaccarelli, Emanuela; Sciortino, Francesco; Colmenero, Juan
Coslovich, Daniele; Bernabei, Marco; Moreno, Ángel J.
Coslovich, Daniele; Bernabei, Marco; Moreno, Ángel J.