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Center for Nonlinear Studies |
Smart polymers are a modern class of soft materials that shows drastic changes in their physical properties by a slight change in external stimuli. One such phenomenon is known as co-non-solvency. Co-non-solvency occurs when a polymer is added to a mixture of two (perfectly) miscible and competing good solvents. As a result, the same polymer collapses into a globule within intermediate mixing ratios. More interestingly, polymer collapses despite the fact that the solvent quality remains good or even gets increasingly better by the addition of the better cosolvent [1]. This puzzling phenomenon, where the solvent quality is completely decoupled from the polymer conformation, is driven by strong local preferential adsorption of better cosolvent with the polymer [1,2]. Because of this discrete particle based nature of the interactions, Flory-Huggins type mean-field arguments become unsuitable. Furthermore, the depletion forces, that are responsible for the standard poor solvent collapse, do not play any role in describing co-non-solvency [3]. This talk will present the microscopic origin of co-non-solvency within a unified framework consisting of grand-canonical (multiscale) modelling, generic simulation and theoretical study to explain the behavior of smart polymers in solvent mixtures. It will be shown that the co-non-solvency phenomenon can be understood within a universal (generic) concept. Therefore, a broad range of polymers is expected to exhibit co-non-solvency and the specific chemical details do not play any role in understanding these complex conformational behaviors [4]. References: [1] D. Mukherji and K. Kremer, Macromolecules 46, 9158 (2013). [2] D. Mukherji, C. M. Marques, and K. Kremer, Nature Communications 5, 4882 (2014). [3] T. E. de Oliviera, P. A. Netz, D. Mukherji, and K. Kremer, Soft Matter 11, 8599 (2015). [4] D. Mukherji, C. M. Marques, T. Stuehn and K. Kremer, Journal of Chemical Physics 142, 114903 (2015). Biography: Debashish Mukherji is a Computation Soft Matter Physicist. He studied Physics at the Banaras Hindu University, India, completing a Masters degree. For his doctoral studies he moved to the University of Western Ontario, Canada. He was then appointed as a research associate within the Army Material Center of Excellence at Drexel University, USA. In September 2010, he joined the theory group of the Max Planck Institute for Polymer Research in Mainz, Germany, where he is currently working as a scientist. His research is concerned with the large-scale molecular dynamics simulations of soft matter properties, which ranges from the polymer physics to (bio)macromolecular solvation. Within this field, he is involved in the development of the scale-bridging (grand canonical) multiscale methods and coarse-grained models for bio-inspired complex systems. He also applies these methods to the realistic systems that include - understanding macromolecular solvation, polymer friction under strong geometric confinements and structure-function relationship of the nano-composites. [More details about this research, publications and academic background can be found on his personal website: http://www2.mpip-mainz.mpg.de/~mukherji/ ]
Host: Stephan Eidenbenz