PhD Oral Qualifying Examination : Polymer Transport in Porous Media

Speaker Nagarajan Karthik (Supervisor: A/Prof Chen Shing Bor)

Host Department of Chemical and Biomolecular Engineering

Date/Time 16 Apr - 16 Apr, 2.00PM

Venue E3-06-12 , Faculty of Engineering, National University of Singapore

Synopsis

The diffusion of linear, ring and star polymers in ordered arrays of spherical cavities and cubic obstacles has been investigated using dissipative particle dynamics (DPD), which rigorously accounts for hydrodynamic interactions and the obstruction effect of the solid mass. The radius of gyration may exhibit non-monotonic variation with the pore size for linear and ring polymers but always decreases with the pore size for stars. The mean square displacement (MSD) of the chains’ centre-of-mass exhibits a sub-diffusive regime under sufficiently strong confinement for both types of porous media. The long-time diffusivity, D, shows a stronger dependence upon the chain length in porous media as compared to free solvent. For cavities, the scaling exponent of D with chain length for linear polymers is consistent with previously reported experimental and Brownian dynamics simulation results. The screening of intra-chain hydrodynamic interactions (HI) was investigated by calculating the short-time MSD of monomers and the relaxation time. For a particular medium, the screening effect is stronger for star polymers as compared to linear or ring polymers.

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