Polymer Thin Film Platforms with Nanostructure and Functions
This event is part of the Biophysics/Condensed Matter Seminar Series.
Abstract: Polymer thin films with nanostructure and functions have recently received much attention due to many important potential applications such as nanolithography and nanopatterning for nanodevices, biologically relevant surfaces for sensors and drug delivery, photonic or electronic devices, and many others. Many nano-objects (such as quantum dots, nanotubes or nanowires, and nanosheets) carrying unique functions should be incorporated into the polymer thin films to achieve such practical goals.
As the first part of this presentation, I will discuss the recent progress in our laboratory in block copolymer thin films: perpendicular orientation and defect minimization of block domains as well as hierarchical structure based on anisotropic buckling. Orientation of block copolymers (BCPs) in thin films is crucial to fully exploit the potential of these materials for applications in nanotechnology. A new approach will be introduced to induce the perpendicular orientation without using neutral brushes (i.e., directly on low-k organosilicate dielectrics). The buckling of mechanically heterogeneous, patterned top films placed on top of elastomeric PDMS substrates will also be presented. Mechanically heterogeneous top films were prepared by either polystyrene (PS) films with topographic patterns or by block copolymer thin films with selective etch. Buckling instability was induced by applying mechanical stresses to the PS-PDMS bilayer. Resulting buckling structure showed the structural change depending on the alignment of the top films with respect to the buckling direction.
In the second part of the presentation, I will demonstrate the formation of functional films incorporating functional nano-objects (such as micelles and QDs). Various functional films can thus be tailored such as tunable optical films, superhydrophobic surfaces (Lotus leaves), QLED devices, and stem cell differentiation (thru porous thin membranes) to name a few.
Considering the wide application areas of both block copolymer and nanocomposite thin films, the approaches taken in present study are likely to open up new possibilities for devices with multifunctional properties.
Biography: Kookheon Char was born in Seoul (Korea) in 1958. He studied Chemical Engineering in the Seoul National University and the Korea Advanced Institute of Science and Technology (KAIST) (both in Korea). He earned his PhD from Stanford University under the joint supervision of Professor Alice P. Gast (president, Imperial College, UK) and Professor Curtis W. Frank (Stanford University, USA). After his post-doctoral research at IBM Almaden Research Center working jointly with Professor Hugh R. Brown (Wollongong University, Australia) and Professor Thomas P. Russell (University of Massachusetts, USA), he returned to Korea to become a professor at the Seoul National University and now a full professor there. He also had work experience in industry (LG Chemical, Korea) and has visited several universities (Cornell University (USA), EPFL (Switzerland), ESPCI (France), and MIT (USA)) during his sabbatical leaves. He published over 280 papers in top-notch journals including papers in Nature Chemistry (2013) and Nature Communications (2011) with over 30 invited talks in major conferences (APS, ACS, MRS etc) during last 3 years. He currently serves as the director of the National Creative Research Initiative Center for Intelligent Hybrids, which is one of the largest funding in Korea by the National Research Foundation of Korea. His awards include the American Physical Society Fellow (USA), the Gutenberg Research College Fellow (Germany), the Gutenberg Research Award (Germany), the National Academy of Engineering of Korea Award for the Best Engineer (Korea), the Best Chemical Engineer Award from KIChE (Korea) among others. He also serves as full members of the National Academy of Engineering of Korea (NAEK) and the Korean Academy of Science & Technology (KAST, Korea).