John P. Hagen
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Research Interests


  Membrane and Surfactant Biophysics

  We study lipid monolayers at the air water interface. A lipid monolayer is essentially half a cell membrane: the polar ends of the lipid molecules are in water, while the non-polar tails extend into the air above the water. In the past, my students have studied monolayers composed of synthetic lipids, and from natural lipids extracted from milk. Students on this project use a Langmuir trough, fluorescence microscopy, and surface potential measurement. 

 
Micelles 
 
  We study the relationship between surfactant and solvent structure and critical micelle concentration. Micelles are of interdisciplinary interest; they have been used to study membrane/water partition coefficients, photosynthesis, the role of lipids in hormone binding, decontamination of polluted water, and drug delivery. My students have used surface tensiometry, conductivity, and light scattering measurements to determine CMC. Light scattering also allows us to monitor micelle size as a function of composition and temperature. One of my students is now using rheometry (the study of liquid flow resistance) to study the sphere-to-rod transition in surfactant solutions. micelle
 
Fluid-Phase Equilibria
 

We study the miscibility of ternary liquid mixtures. Phase diagrams of ternary liquid systems can be used to determine which mixtures will remove chemical wastes from contaminated soil and groundwater most efficiently and to design the separations of liquid mixtures. My students determine the phase diagrams for their systems, and then fit their experimental data to regular solution theory and a temperature-dependent mixing theory.




Chemical Education


  Over the past four years, we have developed an introductory chemistry lab in which students extract natural rubber from milkweed leaves and a general chemistry lab in which students smelt copper. I am now looking for a student to help me design, test, and implement a new general chemistry lab. In this lab, the students would make photosensitive copper foil.  
     
 
Tools
   
  Using ImageJ to determine area fraction