Eur. Phys. J. E 6, 69-77 (2001)
Asymmetric landscapes of early spinodal decomposition
Y. Mao, T.C.B. McLeish, P.I.C. Teixeira and D.J. ReadIRC in Polymer Science and Technology, Department of Physics, University of Leeds, Leeds, LS2 9JT, UK T.C.B.McLeish@leeds.ac.uk
(Received 28 August 2000 and Received in final form 18 July 2001)
Abstract
We address the effect of an asymmetric concentration-dependent mobility on
the early stages of spinodal decomposition in polymer blends and solutions,
and characterise it quantitatively. This is particularly important when
one of the components has a slower dynamics than the other, e.g.,
because it is closer to its glass transition, or is weakly
cross-linked. Composition mode coupling is proposed as the underlying
physical mechanism, and then investigated by means of numerical
simulations of the Cahn-Hilliard equation in one (1d) and two
(2d) dimensions. In general, this coupling broadens the peak in the
structure factor: in 1d an asymmetric concentration profile is obtained,
with sharpened interfaces, whereas in 2d the formation is favoured of
sharp peaks of the phase rich in the more mobile component.
It is shown how the changing morphology of this phase-separating
system can be described with the aid of Minkowski functionals.
64.75.+g - Solubility, segregation, and mixing; phase separation.
61.41.+e - Polymers, elastomers, and plastics.
47.20.Hw - Morphological instability; phase changes.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001
