Compression of Nanoslit Confined Polymer Solutions

Many systems of biophysical and technological interest consist of multiple interpenetrating chains in a confined volume, i.e. a confined polymer solution. Using nanofluidic approaches developed originally for the study of single chains in confined geometries, we develop an assay to create confined polymer solutions on-chip, and then probe the solution response to applied compressive forcing. In our approach, multiple chains are introduced into a nanoslit via hydrodynamic flow, and are then concentrated against a barrier that is permeable only to solvent. For sufficiently high concentration, the compressed solution profile can be described by a mean-field polymer model based on Doi’s two-fluid approach, with the chain free energy described by a Ginzburg type free energy functional. This theory furnishes a partial differential equation based description of the concentration profile in terms of a nonlinear Schrödinger type equation, providing a general theoretical framework for modelling confined polymer solution dynamics.