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SUMMARY:Patterning of Colloidal Particles via Infrared Radiation-Assisted 
 Evaporative Lithography - J.L. Keddie  Department of Physics\, University 
 of Surrey
DTSTART:20120607T103000Z
DTEND:20120607T113000Z
UID:TALK37691@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Colloidal particles in a volatile fluid can be driven laterall
 y by a non-uniformity of the evaporation rate. In the process called evapo
 rative lithography\, the evaporation rate is modulated by holding a mask c
 lose to the fluid surface.  The particles are carried with the water flow 
 to the fast evaporating regions under the open regions in the mask.  Thus\
 , periodic patterns of particles can be created on a surface. We have exte
 nded evaporative lithography by directing infrared radiation through a mas
 k onto concentrated dispersions of polymer particles. Radiative heating in
 creases the evaporation rate locally under the open regions of the mask\, 
 leading to pattern formation.  Furthermore\, the polymer particles are hea
 ted above its glass transition temperature and sinter into a coherent text
 ured coating. We have found that the height of the coating’s topography 
 increases with an increase in several key parameters:  the initial thickne
 ss of the film\, the volume fraction of particles\, and the pitch of the p
 attern.  The results are interpreted by using models of geometry and parti
 cle transport.  The patterned coatings can function as “paintable” mic
 rolens arrays\, applicable to nearly any surface.  Compared with existing 
 methods for creating textured coatings\, IRAEL is simpler\, inexpensive\, 
 able to create a wide variety of bespoke surfaces\, and applicable to near
 ly any substrate without prior preparation.
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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