CAREER: Polymer Langmuir Monolayers: Boundaries, Dynamics and Thermodynamics

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The aim of this project is to investigate the boundary tension and surface viscosity of Langmuir films at the air/water interface, and to determine how to control the structure and dynamic response of Langmuir monolayers. When molecules align at a surface, symmetry is broken leading to long -range electrostatic repulsion between surface molecules. Movement within the monolayer is coupled to the substrate. The combination of hydrodynamics and electrostatics leads to long lived metastable states within the film. The formation of these states, and the relaxation from them, determines the structure and dynamics of biomembranes and are crucial in making Langmuir-Blodgett films. This project will focus on the rheology of isolated islands of dense, phase-separated polymers as monolayer films. The boundary tension will be determined as a function of various parameters such as temperature and molecular weight, and the results compared with theoretical and numerical results. With copolymers, the influence of liquid crystal side chains in increasing fractions on the boundary energy and structure will be explored. A major educational goal is to attract and train a diverse group of students at every educational level, and to encourage interdisciplinary collaborations in addressing the fundamental science of technologically important questions.%%%Langmuir films consisting of molecules self-confined at a fluid surface serve as model quasi-two dimensional systems of technologically and biologically important systems such as foams, emulsions, Langmuir-Blodgett multilayers, and biological membranes. Langmuir-Blodgett films, when sufficiently controlled, are used as liquid crystal alignment layers, as films for non-linear optics, and for modeling bio-membranes.