The Preparation and Characterization of Polymer Nanospheres and Inverse Photonic Crystals

2003 Summer Research Students: Bill Schreiter ('04) and Snadra Obeng ('05)

2004 Summer Research Student: Richard Amankwah ('06) (chemistry)

The preparation of several sizes of polymer (polymethyl methacrylate, PMMA) nanoparticles involves the polymerization of methyl methacrylate in water, (Figure 1).Centrifuging the solutions of the nanospheres causes them to form a close-packed structure, whose order causes the samples to exhibit an opalescence in visible light. The color of this opalescence is again dependent on the size of the nanospheres. From these nanospheres, we can prepare inverse photonic crystals whose pore sizes correlate to the sizes of the nanospheres used in the preparation. Both the nanospheres and inverse photonic crystals can be characterized with a conventional light microscope. In addition, students can bring their samples to campus and use the scanning electron microscope (SEM) to further characterize the spheres (Figure 2) and inverse photonic crystals.

Figure 1: The set-up for the one-pot synthesis of the PMMA nanospheres.

Reference: R. Schroden, N. Balakrishnan, An Inverse Opal Photonic Crystals Laboratory Guide, 2001, University of Minnesota, http://www.mrsec.umn.edu/ehr/learningmod.shtml

Link: Synthesis of PMMA spheres and inverse photonic crystals
Link: Characterization of PMMA spheres by colloidal crystal diffraction

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Last updated February , 2006

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