The Interfacial Physics Group

Carnegie Mellon University, Department of Physics

Dissolution of a Physically Entangled Polymer Solution at a Few Times the Overlap Concentration
by Parv Jain



The behavior of a physically entangled, semi-dilute polymer solution at a few times its overlap concentration in contact with its solvent is not very well understood. The thesis provides a physical picture of how the dissolution occurs.
      The local viscoelastic properties of a simple uncross-linked flexible polymer of 2.1 wt% 1,000,000 Da Polyethylene oxide solution (PEO) which is at 14 times its overlap concentration in 50%-50% H2O-D2O mixture are measured. The PEO solution is placed in contact with pure solvent and the local viscoelastic properties of the solution (both on the PEO solution and H2O-D2O mixture sides of the interface formed) are measured by characterizing the thermal motion of micron sized carboxylate modified fluorescent polystyrene beads as a function of distance from the interface and time across the solution using one point microrheology.
      Two major conclusions are drawn.  (1.) The PEO phase swells due to water flux into the polymer network.  The swelling is monotonically increasing with time at a fixed distance from the interface and monotonically decreasing with distance from the interface in the PEO phase at a fixed time after the interface is formed. (2.) Little or no polymer escapes from the entangled network of the polymer matrix and moves across the water region above the interface.