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Dynamically Available Volume: A Novel Order Parameter for Dense and Nearly Arrested Systems
Author(s) -
Dawson Kenneth A.,
Lynch Iseult,
Lawlor Aonghus,
de Gregorio Paolo
Publication year - 2006
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200600118
Subject(s) - volume (thermodynamics) , diffusion , process (computing) , usable , clarity , polymer , order (exchange) , particle (ecology) , space (punctuation) , nanotechnology , chemical physics , computer science , chemistry , biological system , physics , statistical physics , materials science , thermodynamics , nuclear magnetic resonance , geology , biochemistry , oceanography , finance , biology , world wide web , economics , operating system
Summary: Many common materials ‘solidify’ upon a small change in their surroundings (such as temperature or pH), and the underlying phenomenon is the collective slowing of the motion of the constituent molecules. Examples include gels, polymers, proteins, and other soft matter systems. It has been known for some time that ‘arrest’ is related to some concept of ‘free volume’. However, it has emerged more recently that the important parameter is the volume usable in the long‐ranged reorganisation of the system (the dynamically available volume, DAV) as this determines mobility in these systems. The DAV diminishes as systems arrest, and this is the canonical order parameter for understanding the arrest of complex systems. This idea has been taken a step further here, wherein it is clearly indicated that thermal fluctuation effects can be accommodated within the DAV scenario.Dynamically available volume (DAV) i.e, the empty space that is available to promote long‐ranged motion, and hence diffusion is shown here (the shaded polygonal volume, overemphasized for clarity) to allow the red particle to pass into a neighbouring cage. Repeat of this process is needed for long‐ranged transport (diffusion), and only some DAV is ultimately useful, and therefore termed ‘connected’ DAV.