Angle‐Resolved XPS Study of Plasma‐Deposited Polystyrene Films after Oxygen Plasma Treatment

Abstract

Plasma oxidation of plasma deposited polystyrene (pPS) films was performed in an inductively coupled plasma reactor. Reconstruction of the oxygen concentration depth profiles based on angle‐resolved XPS data showed that two competitive mechanisms (functionalization and etching) happened during the oxygen plasma treatment. Static water contact angle measurements confirmed this result. Oxidized pPS films were also not stable with time; a loss of hydrophilicity was observed and reorganization of the topmost functionalized surface occurred involving diffusion of oxygen groups from the surface towards the bulk and re‐contamination by reaction of trapped radicals with hydrocarbon molecules present in ambient air.

Study of plasma‐polyethylene interactions using electron beam‐generated plasmas produced in Ar/SF6 mixtures

“…The recovery of oxygenated polymers after plasma treatment is well documented and is caused by migration of polar oxygen functionalities from the surface of the polymer toward the bulk. 18,29,30 For the longest treatment time, essentially no change in surface energy was observed. A number of mechanisms could be responsible for this.…”

On the Hydrophilicity and Water Resistance Effect of Styrene‐Acrylonitrile Copolymer Treated by CF4 and O2 Plasmas

“…This phenomenon may be ascribed to the desorption of low molecular weight oxidized materials (LMWOM) in the atmosphere, the diffusion of surface functionalities from the surface into the bulk, as polymer surfaces try to minimize their surface energy, and finally the further reaction of free radicals trapped inside the polymer with unsaturated hydrocarbon, and reactive species from the atmosphere . Molecular rearrangements (possibly the restore of aromaticity) lead to this trait which differs from the ones of aliphatic polymer, such as polypropylene or polyethylene . Concerning the ageing of specimens treated with CF 4 plasmas, they remained non‐wettable even after two weeks of storage, having a small variation of merely 6° within a range of 94−100°, where 94° was the most frequent value measured during the ageing experiments.…”

“…[28][29][30] Molecular rearrangements (possibly the restore of aromaticity) lead to this trait which differs from the ones of aliphatic polymer, such as polypropylene or polyethylene. [31,32] Concerning the ageing of specimens treated with CF 4 plasmas, they remained non-wettable even after two weeks of storage, having a small variation of merely 68 within a range of 94À1008, where 948 was the most frequent value measured during the ageing experiments. There was an increase of at least 168 in the water contact angle, since the water contact angle of SAN was 788.…”

Ultra-Shallow Chemical Characterization of Organic Thin Films Deposited by Plasma and Vacuum-Ultraviolet, Using Angle- and Excitation Energy-Resolved XPS

“…The former is well known as angle-resolved XPS (ARXPS) [7][8][9][10][11][12][13][14][15][16] (references cited here deal exclusively with plasma-prepared materials), while the latter typically involves modulation of the excitation energy by using X-rays from synchrotron sources: Named energyresolved XPS (ERXPS), it was only recently developed and is so far the object of just a few contributions relating to catalysis and to organic materials [17][18][19][20][21][22].…”