Abstract
Facile directed self-assembly (DSA) of multicomponent thin films is important for potential technological applications. This requires a fine control of a complex interplay of processing parameters that need to be properly optimized for different organized structures. This talk will discuss some of our recent success towards realizing tunable DSA of soft matter multicomponent systems involving a dispersion of polymer-grafted nanoparticles in block copolymer or homopolymer matrices. DSA methods for such multicomponent films will be discussed. These include the use of zone-annealing with soft-shear to create highly anisotropic nanoparticle arrays, while direct immersion annealing (DIA) has been used to order nanoparticle filled films by dipping the films into controlled solvent quality solvent mixtures. A recently observed phenomenon of confinement driven entropic order and phase segregation of polymer grafted nanoparticles in similar and dissimilar polymer matrices in melt state will be discussed. A high density of nano particles of different types ranging from metallic to inorganic to organic were patterned almost exclusively into channels via topographical soft confinement using entropic forces. Enthalpic interactions between the nanoparticle grafted layer and the polymer matrix could be used as a further handle to tune the directed assembly of the nanoparticles. The phenomena will be discussed in terms of confinement parameters, partition coefficient, free energy gain and entropic versus enthalpic interactions.
Biography
Alamgir Karim is professor in the Department of Polymer Engineering at the University of Akron, where he holds the Goodyear chair, and is Director of Materials of the Akron Functional Materials Center. From 2010 to 2015, he served as Associate Dean (Research) and Director of Maurice Morton Institute. Previously, Karim was at the National Institute of Standards at Technology NIST where he led the Nanostructured Materials and Combinatorial groups of the Polymers Division, MSEL (1993-2008). Karim is a pioneer of interdiffusion studies in polymer thin films, primarily using neutron reflection, and was awarded his PhD (Northwestern 1991) with P. Dutta, G Felcher (Argonne) and T. Russell (IBM), followed by a postdoc at the University of Minnesota with Frank Bates and Matt Tirrell. He has authored over 200 research articles, reviews and books, is the recipient of numerous awards, and is a Fellow of the American Physical Society (APS, 2005) and the American Association for the Advancement of Science (AAAS, 2012).