Significance of Hydrogen–Deuterium Exchange at Polyolefin Surfaces on Exposure to Ammonia Low-Pressure Plasma

Abstract

Since more than 40 years ammonia plasma exposure of polyolefins is used for introduction of primary amino groups. The selectivity of this reaction and the yield in primary amino groups was found to be low. Here, a prominent side-reactions of this process was investigated, the hydrogenation by NH 3 plasma. For identification of hydrogenation ammonia (NH 3 ) and deuterated ammonia (ND 3 ) were exposed to polyethylene (h-PE) and fully deuterated polyethylene (d-PE) as well as hexatriacontane (h-HTC) and fully deuterated hexatriacontane (d-HTC) as low-molecular weight model for PE. H-D exchange was assumed and detected by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflectance (ATR-FTIR) and 1 H and 2 H Nuclear magnetic Resonance. Results show a significant H-D exchange within the sampling depth of ATR (2.5 lm). However, N-and NH 2 introduction was limited to the topmost surface as shown by SIMS and XPS (a few nanometers).

Adhesion promotion of thick fire-retardant melamine polymer dip-coatings at polyolefin surfaces by using plasma polymers

“…[21] Schiff's base or azomethine bonds were formed. 1 PFBA molecule was bonded to 1 NH 2 group [22,23]:…”

E‐ and H‐mode transition in a low pressure inductively coupled ammonia plasma

“…[27] Common techniques for characterizing ammonia plasma include chemical ionization mass spectrometry (CIMS), [28] infrared absorption spectroscopy (FTIR), [24] Langmuir probes, [20] optical emission spectroscopy (OES), [9,12,13,16,18,[20][21][22] laser interferometry, [9] and mass spectroscopy by RGA. [9,21] Many of the experimentalists used RF inductively (ICP) [9,11,12,[15][16][17][18][19][20][21]23,27,29] and capacitively (CCP) [8,22,24,30] coupled systems for generating the discharge. Details about the experimental setup are rarely described in the cited literature; often only external parameters, such as the gas pressure and discharge power, at which the experiment was performed, are given.…”

Molecular Surface Analysis and Depth-Profiling of Polyethylene Modified by an Atmospheric Ar-D2O Post-Discharge

“…In that investigation, H 2 O was replaced by D 2 O in order to discriminate the H contributions coming from the polymer itself and the atmospheric moisture from the water deliberately mixed to the plasmogen gas. This approach exploited the high sensitivity and selectivity of the SIMS technique for the detection of H isotopes contained in molecular ion fragments present in the outermost layer of the specimen, a capability that is out of reach of XPS . The H‐D exchange in the surface region was thoroughly studied.…”

“…This approach exploited the high sensitivity and selectivity of the SIMS technique for the detection of H isotopes contained in molecular ion fragments present in the outermost layer of the specimen, a capability that is out of reach of XPS. [20][21][22][23][24] The H-D exchange in the surface region was thoroughly studied. It was found that the most important modifications of the LDPE take place for a torch-sample distance of 5 mm, with 25% of deuterated repeat units at the surface.…”