Evidence for the Existence of an Effective Interfacial Tension between Miscible Fluids. 2. Dodecyl Acrylate-Poly(dodecyl acrylate) in a Spinning Drop Tensiometer
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- 作者：Brian Zoltowski ; Yuri Chekanov ; Jonathan Masere ; John A Pojman ; Vitaly Volpert
- 刊名：Langmuir
- 出版年：2007
- 出版时间：May 8, 2007
- 年：2007
- 卷：23
- 期：10
- 页码：5522 - 5531
- 全文大小：396K
- 年卷期：v.23,no.10(May 8, 2007)
- ISSN：1520-5827
文摘
We studied drops of dodecyl acrylate in poly(dodecyl acrylate) (molecular weight of 25 000) in a spinning droptensiometer to determine whether an effective interfacial tension (EIT) existed between these two miscible fluids. Wefound convincing evidence. We estimated the mechanical relaxation time from an immiscible analogue (1-propanoland poly(dodecyl acrylate)) and showed that the dodecyl acrylate drops maintained quasi-steady diameters long afterthis relaxation period. Drops continuously grew in length and became more diffuse, but the width of the transitionzone did not grow with t1/2 as expected from Fick's law although this system had been shown to follow Fick's lawin a static configuration (Antrim, D.; Bunton, P.; Lewis, L. L.; Zoltowski, B. D.; Pojman, J. A. J. Phys. Chem. B 2005,109, 11842-11849). The EIT was determined from Vonnegut's equation, EIT = (
)
2r3/4; both the inner and outerdiameters were measured, yielding values of 0.002 and 0.02 mN m-1, respectively. The EIT was found to be independentof the rotation rate above 6000 rpm and independent of the initial drop volume. The EIT was found to decrease withtemperature and increase with the difference in concentration between the monomer drop and polymer-monomerfluid. The square gradient parameter, k, was determined from EIT = k(c2/
), where c is the difference in molefraction and is the width of the transition zone. The square gradient parameter was on the order of 10-9 N. Thesquare gradient parameter was found to decrease with temperature, to be independent of concentration, and to increasewith the molecular weight of the polymer.
)2r3/4; both the inner and outerdiameters were measured, yielding values of 0.002 and 0.02 mN m-1, respectively. The EIT was found to be independentof the rotation rate above 6000 rpm and independent of the initial drop volume. The EIT was found to decrease withtemperature and increase with the difference in concentration between the monomer drop and polymer-monomerfluid. The square gradient parameter, k, was determined from EIT = k(c2/), where c is the difference in molefraction and is the width of the transition zone. The square gradient parameter was on the order of 10-9 N. Thesquare gradient parameter was found to decrease with temperature, to be independent of concentration, and to increasewith the molecular weight of the polymer.