2836
Macromolecules 1988,21, 2836-2841
Molecular Organization and Viscosity of a Thin Film of Molten Polymer between Two Surfaces As Probed by Force Measurements R. G.Horn*pt and J. N. Israelachvilit Department of Applied Mathematics, Research School of Physical Sciences, Australian National University, GPO Box 4, Canberra 2601, Australia. Received J u n e I, 1987; Revised Manuscript Received February 12, 1988 ABSTRACT Measurements are presented of the force between two molecularly smooth mica surfaces immersed in liquid poly(dimethylsil0xane) (Dow Coming 200 of nominal viscosity 50 cS) over a range of film thicknesses from 3 to 200 nm. There is a repulsion, attributed to conformational restrictions, when the polymer molecules are confined to a gap less than about 15 nm thick. In extremely thin films (
