eprintid: 17375 rev_number: 19 userid: 1419 dir: disk0/00/01/73/75 datestamp: 2013-02-27 18:49:36 lastmod: 2019-02-02 16:55:10 status_changed: 2013-02-27 18:49:36 type: article metadata_visibility: show item_issues_count: 0 eprint_status: archive creators_name: Xu, X creators_name: Friedman, G creators_name: Humfeld, KD creators_name: Majetich, SA creators_name: Asher, SA creators_email: creators_email: creators_email: creators_email: creators_email: asher@pitt.edu creators_id: creators_id: creators_id: creators_id: creators_id: ASHER title: Synthesis and utilization of monodisperse superparamagnetic colloidal particles for magnetically controllable photonic crystals ispublished: pub divisions: sch_as_chemistry full_text_status: public abstract: We demonstrate fabrication of novel magnetically controllable photonic crystals formed through the self-assembly of highly charged, monodisperse superparamagnetic colloidal spheres. These superparamagnetic monodisperse charged polystyrene particles containing nanoscale iron oxide nanoparticles were synthesized through emulsion polymerization. They self-assemble into crystalline colloidal arrays (CCAs) in deionized water and Bragg diffract visible light. The diffraction from these superparamagnetic CCAs can be controlled by imposition of magnetic fields, which readily alter the CCA lattice constant. We also observe magnetically induced self-assembly of these superparamagnetic particles into CCAs in media such as NaCl aqueous solutions and organic polar solvents, which normally do not permit spontaneous CCA self-assembly. We also find that magnetic fields can strain the face-centered cubic lattice of superparamagnetic CCAs polymerized within hydrogels. The lattice symmetry of this photonic crystal becomes tetragonal. The observed magnetically induced CCA self-assembly enables the development of novel photonic crystal materials and devices. date: 2002-04-09 date_type: published publication: Chemistry of Materials volume: 14 number: 3 pagerange: 1249 - 1256 refereed: TRUE issn: 0897-4756 id_number: 10.1021/cm010811h citation: Xu, X and Friedman, G and Humfeld, KD and Majetich, SA and Asher, SA (2002) Synthesis and utilization of monodisperse superparamagnetic colloidal particles for magnetically controllable photonic crystals. Chemistry of Materials, 14 (3). 1249 - 1256. ISSN 0897-4756 document_url: http://d-scholarship-dev.library.pitt.edu/17375/1/licence.txt