Study of the plasma polymerization of 3-aminopropyltrietoxysilane (APTES) by an open-air atmospheric arc plasma jet for in-line treatments
Abstract
Non-equilibrium atmospheric pressure plasma jet (APPJ) are extensively used for
many in-line industrial treatments related to cleaning, bonding, surface activation or
coating. In this work, an open-air arc plasma jet has been used to polymerize 3-
aminopropyelthrietoxysilane (APTES), which is the most commonly used reagent to
functionalize silica surfaces with amine groups, on various substrates from air/APTES
mixtures.
Nitrogen containing silicon oxide coatings have indeed many interesting applications
ranging from cell culture or protein adhesion to bonding, and the challenge of plasma
deposition is to control the retention of functional groups to satisfy the desired application.
The plasma jet was generated by introducing 1000 L/h of compressed air into a blown arc
plasma torch, with a pulse frequency of 25 kHz. The precursor was introduced as a vapor
by using an evaporator system at heated 220°C for different APTES flow and a varied
interval treatment. The pulsed arc plasma jet used in this work has been characterized by
different diagnostics elsewhere [1].
Briefly, the rotational and vibrational temperatures are respectively around 1000-
1500K and 3000-4000K, while the emission spectra is dominated by the NO2 continuum
chemiluminescence of NO2. Therefore, in such a hot and oxidative environment, one
would not except to have any retention of amine groups which are sensitive to temperature
and oxidation.
Indeed, APTES polymerization has been reported at atmospheric pressure in He DBD
[2], N2 plasma jet [3, 4] or post-discharge of Ar-O2 (1-2%) or Ar-N2 (8%) microwave
plasma [5, 6], but not in hot air discharges.
The results show that the 500 nm thick plasma polymerized APTES coatings deposited
by arc plasma jet are characterized by a relatively high content of nitrogen (2%-8%) as
compared to the monomer (7%). The effect of the APTES Flow and the interval treatment
on the structure of APTES films was investigated via ATR-FTIR, XPS and (SEM)-FEG
in order to analyze the coatings and Both of XPS and ATR-FTIR analysis indicated the
presence of amine nitrogen groups, up to 86% in the films [7], as well as amides or oximes.
[1] Dowling et al., Plasma Process. Polym. 8, (2011), 717-727;
[2] Lachmann et al., Proc. of ISPC 20, 24-29 July, (2011), Philadelphia, US;
[3] Alba-Elias et al., Thin Solid Films (2013), 540, 125-134;
[4] Mugica-Vidal et al., Surf. Coat. Technol. (2014), 259374-385;
[5] Lecoq et al., Plasma Process. Polym. (2013),10, 250-261;
[6] Gueye et al., Proc. of ISPC 22, 5-10 July (2015), Antwerp, Belgium;
[7] Ben Saïd et al., Plasma Process. Polym. (2016), 13(10), 1025-1035.