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# Eric Mock <ericmock@uiuc.edu>
# requesting 2 days, at minimum=2 days
# beamline 33ID, Structure of Anisotropic Nanoparticles
# instrument 33ID-D SRUSAXS
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# top:/home/www/beamtime-requests/req00980.txt
# UNICAT Member Beam Time Request  #980
# Original UNICAT Member Beam Time Request  #948
# created Tue Apr 25 17:46:28 CDT 2006
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apsrun:
	2006-02

beamline:
	33ID

collaboration:
	Yes

contact:
	ericmock@uiuc.edu

days:
	2

description:
	Anisotropic colloid particles are encountered in applications including coatings, impact modifiers, and photonic crystals. We are interested in controlling the anisotropy of nanoparticles with the goal of building novel microstructures to enhance macroscopic properties.

Previously, we performed side bounce ultra-small angle x-ray scattering (SBUSAXS) on polystyrene spherical and anisotropic nanoparticles in Figure 1. These particles were suspended in sucrose and concentrated to volume fractions of 45%, where they were irridescent, suggesting the particles were ordered. Plotting the scattering intensity of each suspension as a function of wave vector, Q, normailzed by the radius of gyration, it can be seen that the peaks of the anisotropic nanoparticles nearly line up with those of the spheres at such volume fractions (Figure 2), suggesting that the dicolloids order like spheres at volume fractions up to 45%. The spheres and homo dicolloids were further concentrated to volume fractions of 70% in water, where they were in the form of an irridescent powder, suggesting there was order in this highly concentrated phase. Upon plotting the scattering intensity as a function of Q normallized by the radius of gyration, distinct differences are observed between the homo dicolloids and spheres (Figure 3). These results imply that homo dicolloids order in more complex arrangements than spheres at high volume fractions, and that there may be a solid/solid phase transition for the homo dicolloids between a volume fraction of 45% and 70%.

To further explore the ordered structures of anisotropic nanoparticles, we would like to perform experiments on suspensions of small, medium, and large dicolloids at volume fractions of 70% to see if they order differently than spheres, and whether structure is changed as anisotropy is changed.  Then we would like to investigate volume fractions between 45% and 70% in small increments, to explore possible solid/solid phase transitions.

equipment_required:
	

experiment:
	Structure of Anisotropic Nanoparticles

foreign_nationals:
	

hazards:
	There are no hazards associated with the materials, samples, or procedures involved with this experiment.

instrument:
	33ID-D SRUSAXS

instrument_other:
	

minimumdays:
	2

name:
	Eric Mock

nonmembers:
	

submit:
	Submit

unacceptable_dates:
	

z34ID_details:
	


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