Shear-induced stretching of adsorbed polymer chains

Shear-induced stretching of polymer chains adsorbed on a planar substrate is explored by atomic force microscopy experiments to visualize chain configurations of a dried spinning droplet containing poly[methacryloyloxyethyl- dimethyl-(3-pyrrol-1-yl-propyl)ammonium bromide] (PME-D-AB) in solution. For increasing shear rates, a considerable proportion of stretched chain configurations is found, which is characterized by an increasing (positive) skewness of the chain size distribution function. This behavior is also reproduced by Brownian dynamics computer simulations if the shear gradient direction is perpendicular to the wall, but not for the situation where the shear vorticity is normal to the wall.