Gas Sorption into Surface of Poly(methyl methacrylate) Films at Atmospheric Pressure

Abstract

ABSTRACT:Interfacial structure of deuterated poly(methyl methacrylate) (dPMMA) and polystyrene (dPS) films with gases such as carbon dioxide (CO 2 ) and nitrogen (N 2 ) under a pressure of 0.1 MPa was examined by neutron reflectivity (NR). The interface was analyzed using a model that the density of the outermost region of the films was lower than that of the interior region. The density profile was expressed by a single exponential equation with a decay length (). The values for the dPMMA films under CO 2 and N 2 were larger than that under vacuum at a given temperature, and the extent was more remarkable under CO 2 than under N 2 . On the other hand, such a gas sorption was not clearly discerned for the dPS films. Finally, the surface relaxation in the dPMMA and dPS films under CO 2 and N 2 was discussed on the basis of lateral force measurements.

Load-Induced Frictional Transition at a Well-Defined Alkane Loop Surface

“…A +x/−x pair of scan lines gave a frictional loop, whose average voltage difference for back and forth is a measure of frictional force. 28 The scanning rate was kept at 1.0 μm•s −1 , while the load applied to the cantilever was varied from 4 to 22 nN. For each data point, three frictional loops at different locations on the same sample were collected to average over them.…”

“…The extent of the torsion of the cantilever was detected. A + x /– x pair of scan lines gave a frictional loop, whose average voltage difference for back and forth is a measure of frictional force . The scanning rate was kept at 1.0 μm·s –1 , while the load applied to the cantilever was varied from 4 to 22 nN.…”