DR. MATTHEW MOFFITT Ph.D. 1998, McGill University (A. Eisenberg) NSERC Postdoc, University of  Toronto (M. Winnik)   Phone: 721-7162 Fax: 721-7147 E-mail: mmoffitt@uvic.ca

    PROJECTS                                                        THE GROUP                                    STRUCTURAL GALLERY

Structural hierarchy is found everywhere around us: Nature is the grand architect of complex systems with function arising from organization on a multitude of length scales. Spurred by the growing need for a new generation of advanced materials for computing, data storage and information transfer (among other applications), chemists have just recently begun to follow Nature's lead-- creating specially-designed nanoscale building blocks which self-assemble into complex structures under controlled conditions. Research in our group targets the use of spontaneous structure-forming processes in polymer systems (e.g. phase separation, dewetting, micellization) for the design of polymer/inorganic nanocomposites with properties determined by organization on a combination of length scales. "Tuning in" of specific function is the ultimate goal, by establishing precise control over (1) the size and (2) the organization (patterning) of nano-sized inorganic structural elements (quantum dots) in a polymer matrix. These issues are addressed using self-assembly strategies to pattern hybrid polymer/nanoparticle building blocks over length scales ranging from a few nanometers to several micrometers.

Block copolymers are synthesized in our group using controlled anionic polymerization techniques. The self-assembly of these materials in various environments (e.g. solutions, polymer blends, surfaces) results in a wide range of polymer and polymer/nanoparticle structures, which are probed over a range of length scales using transmission and scanning electron microscopy (TEM, SEM), atomic force microscopy (AFM), laser scanning confocal fluorescence microscopy (LSCFM), and light scattering.  Various spectroscopic techniques, including static and time-resolved fluorescence, optical reflectance and UV-vis absorption spectroscopy, are used to establish relationships between structure and optical properties, exploring the potential for new nonlinear optical materials, photonic bandgap colloidal crystals, and light-emitting elements for photonic circuits.

(a) Synergistic self-assembly of polystyrene-stabilized CdS nanoparticles (PS-CdS) and polystyrene-b-poly(ethylene oxide) (PS-b-PEO) copolymer results in hierarchical nanoparticle/polymer features at the air-water interface; (b) atomic force microscopy and (c) transmission electron microscopy of the resulting nanoparticle/polymer nanowires. In (c), a nanowire is being stretched by tensile forces exerted by a rip in the formvar substrate; the CdS nanoparticles are visible dispersed within the polymer matrix.

4. Yusuf, H.; Kim W.-G.; Lee, D. H.; Aloshyna, M.; Brolo, A. G.; Moffitt, M. G., 2007 A Hierarchical Self-Assembly Route to Three-Dimensional Polymer-Quantum Dot Photonic Arrays. Langmuir, 23, 5251-5254.

Interesting Links

BC Research in Nano Optics (BC-RiNO)