Effect of the chain length of the molecule of saturated hydrocarbons on the chemical structure and morphology of polymer films formed in low temperature plasma

Abstract

Previously, we have investigated the formation of polymer films from heptane on the surface of a metal substrate in low-temperature plasma (LTP) by varying the mode and time of plasma treatment [1–3]. It was found that the formation of the films occurs in three stages, each being characterized by certain topography, chemical structure, and mechanical properties of the films. In the first stage, continuous films are formed that mimic the substrate topography, smoothing it. The films are homogeneous in their chemical structure, have a low hardness, high permeability, and hydrophilicity. In the second stage, the films grow via the formation of isolated macromolecular entities, “islets.” At the end of the second step, the entire surface of the films is covered by the islets, and the films have a maximum hardness, low permeability, and hydrophobicity. In the third stage, the polymer chains undergo degradation accompanied by the intense etching of the film, which manifest itself in a reduction of its thickness, smoothing of the topography, enhancement of permeability, and surface hydrophilicity. In this study, we examined the effect of the chain length of saturated hydrocarbon molecules on the chemical structure and morphology of the polymer films formed in low-temperature plasma.