Abstract:Plasma polymers have been formed from acrylic acid using a pulsed power source. An on-pulse duration of 100 micros was used with a range of discharge off-times between 0 (continuous wave) and 20,000 micros. X-ray photoelectron spectroscopy (XPS) has been used in combination with trifluoroethanol (TFE) derivatization to quantify the surface concentration of the carboxylic acid functionality in the deposit. Retention of this functionality from the monomer varied from 2% to 65%. When input power was expressed as … Show more
“…The simultaneous synthesis and deposition of thin polymeric coatings via plasma sustained in organic vapors to form plasma polymers has attracted significant interest for a wide range of applications [1]. However, the numerous applications of plasma deposition require an optimization of the process to obtain a high degree of preservation of the functional groups of the monomers.…”
Thin poly(acrylic acid) PAA films were deposited by pulsed plasma polymerization on different organic and inorganic substrates. The structure-property relationships of the deposited acrylic acid polymers were studied in dependence on the monomer pressure by various techniques and probes. The surface and bulk properties of the plasma deposited films were investigated by X-ray photoelectron spectroscopy, attenuated total reflection infrared, and broad band dielectric spectroscopy. The experimental infrared frequencies of PAA films are compared with those predicted from quantum mechanical calculation. The concentration of the COOH groups in the film (stored in ambient air) decreased by about 15 % compared to the as-prepared sample. The plasma deposited PAA probably form a highly branched product. However, the dielectric measurements show that in addition to the hydrogen bonds, self condensation process was able to hinder the localized fluctuation as well. These processes lead to form a cross-linked network polymer film. Nevertheless, a low energy is sufficient to break these processes during heating at atmospheric pressure. Therefore, homogenized samples with free branches (functional group) were obtained after a first heating with structures close to conventional polymerized acrylic acid. Thus, a thermally stable product was obtained.
“…The simultaneous synthesis and deposition of thin polymeric coatings via plasma sustained in organic vapors to form plasma polymers has attracted significant interest for a wide range of applications [1]. However, the numerous applications of plasma deposition require an optimization of the process to obtain a high degree of preservation of the functional groups of the monomers.…”
Thin poly(acrylic acid) PAA films were deposited by pulsed plasma polymerization on different organic and inorganic substrates. The structure-property relationships of the deposited acrylic acid polymers were studied in dependence on the monomer pressure by various techniques and probes. The surface and bulk properties of the plasma deposited films were investigated by X-ray photoelectron spectroscopy, attenuated total reflection infrared, and broad band dielectric spectroscopy. The experimental infrared frequencies of PAA films are compared with those predicted from quantum mechanical calculation. The concentration of the COOH groups in the film (stored in ambient air) decreased by about 15 % compared to the as-prepared sample. The plasma deposited PAA probably form a highly branched product. However, the dielectric measurements show that in addition to the hydrogen bonds, self condensation process was able to hinder the localized fluctuation as well. These processes lead to form a cross-linked network polymer film. Nevertheless, a low energy is sufficient to break these processes during heating at atmospheric pressure. Therefore, homogenized samples with free branches (functional group) were obtained after a first heating with structures close to conventional polymerized acrylic acid. Thus, a thermally stable product was obtained.
“…[4,7,23] The influence of both plasma-chemical (gas phase) and physical (ioninduced) effects have been discussed in order to explain this finding. [24][25][26] Considering the enormous difficulties associated with the application of microscopic kinetics to plasma chemistry, a coarser method, macroscopic kinetics, is used in this work to examine the deposition of a-C:H(O) coatings from CO 2 /C 2 H 4 RF discharges.…”
“…The plasma ''on-time'' (t on ) was fixed at 0.5 ms which was more than enough for the plasma to reach a steady state (which takes typically 0.02-0.05 ms). [32] The peak power (P peak ) was kept constant at 100W corresponding to an inductive coupling. [18] Table 1 summarizes the different experimental conditions employed in this work.…”
Section: Methodsmentioning
confidence: 99%
“…For sake of clarity, due to the high production of atomic and molecular hydrogen in the discharge as usually encountered in plasma polymerization, the spectra are presented from m/z ¼ 10 to 100. [23] In order to take into account the fragmentation of the precursor in the spectrometer itself, each signal recorded in the plasma was treated following Equation (3): [32] I c ðmÞ ¼ I m ðPlasma ONÞ À I m ðPlasma OFFÞ:…”
In this work, the plasma polymerization of propanethiol is investigated with the aim to control the thiol density [SH] in the coatings. The results reveal a nearly constant evolution of [SH] regarding the mean power dissipated in the discharge. This peculiar behavior is explained considering (i) mass spectrometry data revealing a similar relative concentration of condensable SH-bearing species in the plasma and (ii) similar energetic conditions at the growing film/plasma interface. Finally, it is observed that the low hPi synthesized films are not chemically stable in solution likely due to the release of H 2 S molecules trapped in the material network. The whole set of our data allows to provide a deeper understanding of the growth mechanism of propanethiol plasma polymer, essential for future development.
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