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BEGIN:VEVENT
DTSTAMP:20261020T151404Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20120406T140000Z
DTEND:20120406T150000Z
UID:event910@bu.edu
URL:http://physics.bu.edu/internal/events/show/910
SUMMARY:The Effect of Solvent Swelling on the Properties of Polystyrene Thi
	n Films
DESCRIPTION:Featuring Andrew Clough\n\nPart of the Preliminary Oral Exam.\n
	\nExamining Committee:  Ophelia Tsui\, Rama Bansil\, Edward Kearns\, A
	natoli Polkovnikov\nAbstract:\nSeveral properties of polymer thin films\, i
	ncluding viscosity and glass transition temperature\, exhibit deviations fr
	om the bulk.  While the thin film behavior is likely due to the increa
	sing importance of both surface effects and confinement of the polymer chai
	ns as the film thickness decreases\, there is currently no consensus on exa
	ctly what is responsible for many experimental observations.  In addit
	ion\, it has been observed that sample preparation and history can influenc
	e certain properties of polymer thin films.  In particular\, by spin-c
	oating from solutions of different solvent qualities the resulting films wi
	ll have different initial chain conformations.  We surmise that upon f
	ormation by spin-coating\, the chain conformation of a film is still adjust
	able by means of solvent swelling\, resulting in modifications to the amoun
	t of entanglement and free volume.  Initial measurements of thermal ex
	pansion upon heating after swelling suggest that there is a difference betw
	een polystyrene films swelled with a good solvent and a near-theta solvent.
	  A more detailed investigation studying the effect of swelling on the
	 dewetting behavior of the film indicates that the quality of the solvent a
	ffects the characteristic aging time associated with the growth rate of dew
	etting holes.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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