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Cooperativity in the Conformational Rearrangements of Polymer Chain Segments as Seen by Bond Fluctuation Model
Author(s) -
Torregrosa Cabanilles Constantino,
Meseguer Dueñas José María,
Gómez Ribelles José Luis,
MolinaMateo José
Publication year - 2009
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.200900008
Subject(s) - cooperativity , markov chain , thermodynamics , polymer , relaxation (psychology) , chain (unit) , statistical physics , chemistry , energy landscape , chemical physics , physics , mathematics , psychology , social psychology , biochemistry , statistics , organic chemistry , astronomy
Abstract The kinetics of structural relaxation was simulated using the bond fluctuation model. Annealing of the system in the glassy state produces a clearly nonexponential decrease in the energy in a certain temperature interval. At lower temperatures, the decrease in energy takes place by successive small steps, due to the change of the energy of individual polymer chains that modify their conformation into small neighbourhoods. This cooperativity is behind the nonexponential behaviour shown by structural relaxation at higher temperatures. A second order Markov chain is able to reproduce the nonexponentiality with quite good agreement with the bond fluctuation simulated curves. Cooperativity comes from the fact that the transition probability of a polymer chain between two energy levels depends on the history of previous transitions that took place in its neighbourhood.