Effect of Irradiation Power on Surface Modification of Polyester by Ammonia Plasma Treatment

Abstract

The power dependence of nitrogen functional group introduction treated with ammonia plasma on poly(ethylene terephthalate) (PET) and liquid crystal polymer (LCP) was investigated. The ratios of NH2 and N–C=O groups, which are the introduced functional groups, differ depending on the power used for plasma generation. The ratio of N–C=O groups increases with increasing power. For PET, the introduction of oxygen functional groups occurs at low power. Power dependences of contact angles were found for PET and LCP. They are related to the different types and quantities of functional groups with respect to the power. A considerable decrease in contact angles is apparent at the low-power side of 0–15 W.

Nitrogen plasma functionalization of low density polyethylene

“…This supports that the new oxygen functional groups incorporated onto the surface during the conventional plasma treatments are mainly responsible for this macroscopic modification of the surface properties. Although further studies are still necessary (e.g., to discard the effect of the different surface topographies on the WCA variations or to ensure that the amine groups on the surface are not affected/removed when the polymer is brought in contact with the water droplets used for WCA measurements [50]), we can conclude that, contrary to what has been previously claimed in literature [16,19,41,42], nitrogen functional groups, including amine groups, do not induce a significant surface hydrophilicity. In a similar line of reasoning, it can be tentatively proposed that the partial solubility of nitrogen plasma treated polymers reported by Girard-Lauriault et al [50] can be due to the simultaneous incorporation of oxygen functional groups on the polymer surfaces.…”

“…This shoulder increased slightly in intensity after the treatment of the untreated samples with the different plasmas. Such an increase has been usually attributed to the surface incorporation of oxygen and/or nitrogen functional groups characterized by different binding energies: C-N/C-O (285.9 eV), C≡N (286.7 eV), N-CjO/CjO (287.6 eV) and N-C(jO)-N/O-CjO (288.9 eV) [31,[39][40][41][42]. Because of the superposition in this spectral region of the possible contribution of quite different functional groups of carbon bonded to oxygen and/or nitrogen, no fitting analysis will be intended here.…”

“…An important point in this regard is to determine whether the amine and/or the oxygen functional groups incorporated onto the surface are responsible for the modification of the surface energy after plasma treatments. This point is controversial as most plasma activation experiments aiming at the amine functionalization of polymer surfaces end up with the simultaneous incorporation of oxygen functional groups [42]. A related open question is the solubility of amine groups in water and other solvents.…”

Low Pressure Radio Frequency Ammonia Plasma Surface Modification on Poly(ethylene terephthalate) Films and Fibers: Effect of the Polymer Forming Process

“…Indeed, Narushima et al described various ester scission mechanisms in ammonia plasma leading either to carboxylic acid, amide, and amine group formation through the decarboxylation process [15]. Moreover, several authors clearly demonstrated that the aromatic ring is a key parameter in amine formation, as the benzene ring allows for the stabilisation of the radical that is formed following the decarboxylation process [1,[15][16][17]. However, these authors reported a decrease of the aromatic ring p -p* shake-up band, with no further explanations.…”

“…Plasma treatment is a popular technique because it is a dry process (environmentally friendly) and allows for greater uniformity of the modified surface, hence it is widely used for industrial applications [2,14]. Furthermore, plasma treatments enable the modification of the first atomic layers of the surface without changing the bulk properties of the material [2,6,8,15,16]. Moreover, depending on the plasma gaseous environments and experimental parameters, surface modification can be modulated to privilege etching (degradation of polymeric chains) or/and surface functionalisation [1,2,14,15,[17][18][19][20][21].…”