Evidence for the Existence of an Effective Interfacial Tension Between Miscible Fluids. 2. Dodecyl acrylate-poly(dodecyl acrylate) in a Spinning Drop Tensiometer

Authors

Brian Zoltowski, University of Southern MississippiFollow
Yuri A. Chekanov, University of Southern MississippiFollow
Jonathan Masere, University of Southern Mississippi
John A. Pojman, University of Southern MississippiFollow
Vitaly Volpert, Université LyonFollow

Document Type

Article

Publication Date

5-8-2007

Department

Chemistry and Biochemistry

School

Mathematics and Natural Sciences

Abstract

We studied drops of dodecyl acrylate in poly(dodecyl acrylate) (molecular weight of 25 000) in a spinning drop tensiometer to determine whether an effective interfacial tension (EIT) existed between these two miscible fluids. We found convincing evidence. We estimated the mechanical relaxation time from an immiscible analogue (1-propanol and poly(dodecyl acrylate)) and showed that the dodecyl acrylate drops maintained quasi-steady diameters long after this relaxation period. Drops continuously grew in length and became more diffuse, but the width of the transition zone did not grow with t^1/2 as expected from Fick's law although this system had been shown to follow Fick's law in a static configuration (Antrim, D.; Bunton, P.; Lewis, L. L.; Zoltowski, B. D.; Pojman, J. A. J. Phys. Chem. B2005, 109, 11842−11849). The EIT was determined from Vonnegut's equation, EIT = (Δρ)ω²r³/4; both the inner and outer diameters were measured, yielding values of 0.002 and 0.02 mN m^-1, respectively. The EIT was found to be independent of the rotation rate above 6000 rpm and independent of the initial drop volume. The EIT was found to decrease with temperature and increase with the difference in concentration between the monomer drop and polymer−monomer fluid. The square gradient parameter, k, was determined from EIT = k(Δc²/δ), where Δc is the difference in mole fraction and δ is the width of the transition zone. The square gradient parameter was on the order of 10^-9 N. The square gradient parameter was found to decrease with temperature, to be independent of concentration, and to increase with the molecular weight of the polymer.

Publication Title

Langmuir

Volume

23

Issue

10

First Page

5522

Last Page

5531

Recommended Citation

Zoltowski, B., Chekanov, Y. A., Masere, J., Pojman, J. A., Volpert, V. (2007). Evidence for the Existence of an Effective Interfacial Tension Between Miscible Fluids. 2. Dodecyl acrylate-poly(dodecyl acrylate) in a Spinning Drop Tensiometer. Langmuir, 23(10), 5522-5531.
Available at: https://aquila.usm.edu/fac_pubs/9018