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Laser Light as Directing Agent for Ordering Self-Assembling Nanomaterials

March 30 , 13:00 14:00

Speaker: Prof. Paweł Majewski
Affiliation: Faculty of Chemistry, University of Warsaw, Warsaw, Poland
Link to MSTeams meeting

Block copolymers (BCPs) due to chemical incompatibility between the blocks undergo microphase separation and self-assemble into a variety of periodic nanostructures. Although at equilibrium the morphology of these nanostructures is primarily defined by the chemical makeup of the polymer chains and free-energy minimization principles, BCP self-assembly is frequently not reaching a thermodynamically defined state, i.e., a monodomain.  The morphologies which form in the absence of directing biases tend to be kinetically trapped in local energy minima and their evolution towards the global minimum is effectively stopped. In our work, we investigate photothermal methods for block copolymer processing in lieu of conventional thermal methods, i.e. oven annealing. We have shown how the process of self-assembly can be accelerated and directed by steep temperature gradients induced in BCP thin films by irradiation with a high-intensity laser beam and how laser-annealed BCP films can be further used for surface nanopatterning, e.g., formation of optically anisotropic arrays of metallic nanowires and multilayered nanomeshes. Currently, we focus on in-situ investigations of the mechanism of laser-driven self-assembly extending our studies to other soft materials such as liquid crystals and liquid crystal nanoparticle composites. We utilize the photothermal approach to direct the ordering of these materials and to control their morphology both at shortest length scales determined by thermally activated supramolecular interactions and at the macroscopic level controlled by laser light distribution, enabling formation of complex geometrical patterns with spatially-controlled optical properties.

Chaiman: Prof. Jacek Gapiński

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