When 3:30 PM - 5:00 PM Nov 15, 2013
Where 1670 Beyster Building
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Capturing the Dynamics of Structure Development in Liquid-Applied Coating and Printing Processes


Lorraine Francis
University of Minnesota, Department of Chemical Engineering and Materials Science

A wide variety of products, including paints, adhesives, membranes, fuel cell components, printed electronic circuits and newsprint, are produced by liquid-applied coating and printing processes. A coating or printing process has two main steps: deposition of a liquid (e.g., solution, dispersion) onto a substrate and solidification of the liquid layer, typically by drying or curing, into a functional coating or printed patch. This seminar will focus on our efforts to understand and characterize the tremendous changes in properties and structure that occur dynamically during drying and curing of a coating or printed pattern.  Two of these special techniques will be discussed: cryoSEM and microrheology.  Cryogenic SEM (cryo-SEM) involves freezing coatings at different stages of drying, fracturing to reveal cross-sections, subliming for contrast and imaging with an SEM equipped with a cryostage. Magnetic microrheology has been developed as a tool to characterize the viscosity of a coating in situ.  A small quantity of magnetic particles is added to the coating liquid, which is then deposited onto a substrate and mounted in a specially designed apparatus.  A magnetic field is applied and the velocity of the particles is then monitored with an optical microscope. Both methods have been applied to a variety of coating and printing systems, including block copolymer solutions, polymer latex, ceramic colloidal dispersions, and silver nanoparticle inks, and the results have revealed new and important details of the structure development. 

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