SWELLING IN ORGANIC-INORGANIC MULTILAYER SYSTEMS

We have investigated the swelling of organic-inorganic structures base d on fluorocarbon polymer (CF2) layers sandwiched by two layers of ino rganic ionic (HfO2) and inorganic covalent (CdS) materials. The swelli ng of the CF2 layer produces cracks on the uppermost inorganic layer. The cracks form a network of hexagonal defects with random distributio n. The extension of the pattern and the mean unit size have been measu red for different solvents by using a purposely developed optical prof ilometer. We show that the swelling phenomenon strongly depends on the polar forces between the: molecules of the solvent and those of the i norganic layers. The electric dipole moment of the solvents and the io nicity of the inorganic materials are thus the crucial parameters infl uencing the crack density and shape. (C) 1998 American lnstitute of Ph ysics.