Abstract
Thermally activated flow dynamics of polystyrene films supported by silicon is studied for a wide range of film thickness (h0) and molecular weights (Mw). At low Mw, the effective viscosity of the nanometer thin films is smaller than the bulk and decreases with decreasing h0. This is due to enhancement of the total shear flow by the augmented mobility at the free surface. As Mw increases, with h0 becoming smaller than the polymer radius of gyration (Rg), the effective viscosity switches from being substrate-independent to substrate-dependent. We propose that interfacial slippage then dominates and leads to plug flow. The friction coefficient is found to increase with h0 providing h0/Rg < ∼1, demonstrating a surface-promoted confinement effect.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
