Ultralow interfacial tensions of polymer/polymer interfaces with diblock copolymer surfactants

Kwanho Chang, Christopher W. Macosko, David C. Morse

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The interfacial tension γ between polyisoprene (PI) and polydimethylsiloxane (PDMS) homopolymers mixed with poly(isoprene-b- dimethylsiloxane) (IDMS) diblock copolymers has been measured with a spinning drop tensiometer. Measurements have been conducted for mixtures containing each of 12 copolymers, in which the PDMS volume fraction fDMS varies from 0.49 to 0.73, and for mixtures containing a symmetric copolymer and PI homopolymers of varying molecular weight. The measured interfacial tension is found to be independent of copolymer concentration above an apparent critical concentration of order 0.1 wt % copolymer. Mixtures with a nearly symmetric copolymer are found to exhibit ultralow interfacial tensions, up to 3 orders of magnitude less than that of the bare PI/PDMS interface. Results are compared to the predictions of a numerical self-consistent field theory for the interfacial tension of an interface between a PDMS phase containing swollen spherical micelles and a phase of nearly pure PI. Agreement between theory and experiment is excellent for sufficiently asymmetric copolymers, with fDMS > 0.63. Measured values of γ are significantly lower than predictions for 0.5 < fDMS < 0.6, however, and depend very sensitively upon fDMs over a narrow range 0.60 ≤ fDMS ≤ 0.63. Kinetic limitations that may be relevant to these experiments are also analyzed and discussed.

Original languageEnglish (US)
Pages (from-to)3819-3830
Number of pages12
JournalMacromolecules
Volume40
Issue number10
DOIs
StatePublished - May 15 2007

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