Polymerization of organic compounds in an electrodeless glow discharge. X. Internal stress in plasma polymers

Owing to the unique mechanisms operative in plasma polymerization, a thin layer of plasma polymer deposited on the surface of a substrate shows a tendency to expand, indicating an internal stress in the layer. This stress, σ s , has been estimated from the observed curling of composite membranes in which the thickness of the plasma coating, d , is much smaller than the thickness of a flexible substrate, D , according to the relation\documentclass{article}\pagestyle{empty}\begin{document}$$ \sigma _S = ED^2 /6Rd $$\end{document} where R is the radius of the roll into which the composite films curl up and E is the modulus of the substrate polymer. The stress σ s is found to depend on the kind of monomer used and to be of the order of magnitude 10 8 –10 9 dynes/cm 2 with most of the monomers here employed.