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HYDRODYNAMICS AND LINE TENSION OF LANGMUIR FILMS AT THE AIR-WATER INTERFACE

ZOU, LU
http://rave.ohiolink.edu/etdc/view?acc_num=kent1195625894

Abstract Details

2007, PHD, Kent State University, College of Arts and Sciences / Department of Physics.
A Langmuir film is a well-controllable structure defined as a molecularly thin layer at the gas-fluid interface. This film forms quasi-two-dimensional analogues of gas, liquid, liquid-crystal, solid, and yet other phases if multilayers are possible. Any two of these phases may coexist, with energy associated with the boundary. This energy per unit length, defined as line tension, determines the shape and dynamics of coexisting phases, with possible applications to the multi-component biological cell membranes. A good understanding of this line tension will lead to a better idea of what controls the membrane configuration. In this work, I use Brewster angle microscopy, the Langmuir trough, the Wilhelmy plate technique, the four-roll mill, and other techniques to study the behaviors of different coexistence systems, including polymers and liquid crystals, in Langmuir films at the air-water interface. I use the dynamic response of the monolayers to explore line tension. Previous theories connecting dynamics and line tension in Langmuir films are limited and hard to access experimentally. I have collaborated with a group of mathematicians, physicists, and engineers on developing a hydrodynamic theory considering the coupling between the bulk subfluid phase and the surface phases, which gives a boundary-integral formulation that can be efficiently treated both analytically and numerically. Two cases were considered: hole-closing and domain relaxation. With modifications on some practical experimental techniques to reach the goal of this work, I directly compare these experiments to both analytic and numerical results, in order to both confirm the results and help to develop the new theory. The case of hole-closing in a polymer monolayer directly confronts the usual approximation of strictly horizontal flow. Line tension analyzed with new theory allows a factor of ten improvement in the accuracy and precision of line tension measurements. In the specific case of the coexistence of 4’-n-octyl-4-cyanobiphenyl (8CB) multilayers with different thicknesses, line tension is explored as a function of the thickness difference, which provides a better idea of the structure at the boundary for a case in which existing continuum elasticity theories present a reasonable, testable, first approximation for line tension.
Elizabeth Mann (Advisor)
235 p.
Langmuir film; thin film; air-water interface; Brewster angle microscope; line tension; hydrodynamics; 8CB; edge dislocation; phase coexistence

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Citations

  • ZOU, L. (2007). HYDRODYNAMICS AND LINE TENSION OF LANGMUIR FILMS AT THE AIR-WATER INTERFACE [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1195625894

    APA Style (7th edition)

  • ZOU, LU. HYDRODYNAMICS AND LINE TENSION OF LANGMUIR FILMS AT THE AIR-WATER INTERFACE. 2007. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1195625894.

    MLA Style (8th edition)

  • ZOU, LU. "HYDRODYNAMICS AND LINE TENSION OF LANGMUIR FILMS AT THE AIR-WATER INTERFACE." Doctoral dissertation, Kent State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=kent1195625894

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.