Advances in Colloid and Interface Science
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94 2001 21᎐31
Interplay of entropic and enthalpic
contributions to the surface tension of
polymer melts
Manoel Manghi
U
, Miguel Aubouy
Ser
¨
ice des Interfaces et des Materiaux Moleculaires et Macromoleculaires, UMR No. 5819 CEA,
´´ ´
CNRS and Uni
¨
ersite Joseph Fourier, DRFMC, CEA-Grenoble, 38054 Grenoble cedex 9, France
´
Abstract
The most common observation is that the surface tension of molten polymer liquids is an
increasing function of the molecular weight of the chains. However, when chain ends have
been chemically modified, the opposite trend is found. In this article, we discuss theoreti-
cally, the interplay between segregation effects of chain ends to the surface tension which
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are enthalpic dominated that contribution originated from the small chemical shift between
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end-groups and monomers from the backbone , and an entropic contribution originated
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from the self-organisation of the chains in the immediate vicinity of the interface formation
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of loops . We find that enthalpic contributions are not able to account for the decrease of
surface tension with molecular weight, and plausibly enough, the entropic contribution that
we have considered is responsible for this feature. ᮊ 2001 Elsevier Science B.V. All rights
reserved.
Keywords: Entropic; Enthalpic; Surface tension; Polymer melts
Contents
1. Introduction
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22
2. Enthalpic contribution to the surface tension
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23
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Corresponding author.
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E-mail address: mmanghi@cea.fr M. Manghi .
0001-8686r01r$ - see front matter ᮊ 2001 Elsevier Science B.V. All rights reserved.
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PII: S 0 0 0 1 - 8 6 8 6 0 1 00052-5