Semiconductor quantum dot sensitized multiphoton polymerization

PHYS 132

Nicholas C. Strandwitz, nstrand@engineering.ucsb.edu1, Anzar Khan2, Shannon W. Boettcher, sboettcher@chem.ucsb.edu3, Alexander Mikhailovsky3, Craig J. Hawker, hawker@mrl.ucsb.edu2, Thuc-Quyen Nguyen, quyen@chem.ucsb.edu3, and Galen D. Stucky3. (1) Materials Department, University of California, Santa Barbara, Santa Barbara, CA 93106, (2) Materials Research Laboratory, University of California, Santa Barbara, CA 93106, (3) Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, CA 93106
Colloidal semiconductor nanocrystal quantum dots (QDs) have enormous potential as photosensitizers for inducing chemical transformations due to their ultra-large linear and two-photon absorption (TPA) cross sections, facile synthesis, and low cost processing. TPA potentially allows one to spatially direct chemical transformations by confining excitations in 3D with 100 nm resolution. However, chemical methods have not been developed to translate QD excitations into desired chemical transformations, such as radical polymerization reactions. Here, we present CdS QD surface modifications using amine co-initiators which increase the fraction of excited states that result in polymer formation. We characterize the effects of the amine co-initiators on the QD surface and fluorescence behavior. These amine co-initiator-modified QDs are utilized as photosensitizers for one- and two-photon induced polymerization. Our initial results of increased initiation efficiency coupled with large TPA cross-section values present QDs as possibly the most highly efficient two-photon polymerization photosensitizers to date.
 

Spectroscopy, Chemistry, and Imaging through Nanophotonics
8:20 AM-12:00 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 340/341, Oral

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008