Soft polymerization of hexamethyldisiloxane by coupling pulsed direct‐liquid injections with dielectric barrier discharge

Abstract

This work examines the combination of pulsed direct-liquid injections with dielectric barrier discharge at atmospheric pressure for the deposition of organosilicon coatings using hexamethyldisiloxane (HMDSO) as the precursor and nitrogen as the carrier gas. In such conditions, deposition relies on the charging of micrometer droplets and their transport toward the substrate by the Coulomb force. The thin-film morphology and extent of precursor fragmentation are strongly linked to the amount of energy provided by the filamentary discharge to HMDSO droplets. While cross-linked and smooth coatings were achieved at low energies as in standard gas phase plasma polymers, viscous and droplet-like structured thin films were deposited at higher energies. The latter material is attributed to the soft polymerization of HMDSO droplets related to plasma-droplet interactions.

Direct Liquid Reactor-Injector of Nanoparticles: A Safer-by-Design Aerosol Injection for Nanocomposite Thin-Film Deposition Adapted to Various Plasma-Assisted Processes

“…Indeed, a 5 nm nanoparticle will be charged within 5 ns. Since this charging time was much shorter than (i) the period of the applied electric field (1 ms at 1 kHz), and (ii) the gas residence times linked to pulsed (>3 ms) and continuous carrier gas injections (>50 ms), one could safely assume that all nanoparticles were charged [36]. For a steady-state charge of ~5 electrons per 5 nm ZnO nanoparticles (and thus a massto-charge ratio ~10 −4 kg/C), the amplitude of oscillations of charged nanoparticles in a 4 kV.mm −1 electric field at 1 kHz became much more than to the gas gap (~1 mm).…”

“…However, as reported in Figure 9c,d, the gradients of n and k and, consequ fluorescence previously attributed to ZnO nanoparticles, were smaller in this c reveals that the volume fraction was lower than in the DLRI mode. Indeed, trapp liquid droplets, ZnO nanoparticles transport and deposition were directly cont the droplet transport and deposition [36], i.e., the transport of charged liquid dro their evacuation by the carrier gas. The mass balance thus led to a smaller volum of ZnO nanoparticles [36].…”

“…Indeed, trapp liquid droplets, ZnO nanoparticles transport and deposition were directly cont the droplet transport and deposition [36], i.e., the transport of charged liquid dro their evacuation by the carrier gas. The mass balance thus led to a smaller volum of ZnO nanoparticles [36]. Overall, nanocomposite thin films with ultrafine nan (<10 nm) were prepared by coupling a DLRI system with atmospheric-pressure However, as reported in Figure 9c,d, the gradients of n and k and, consequently, the fluorescence previously attributed to ZnO nanoparticles, were smaller in this case.…”

“…The charging of droplets in plasmas also promotes their electrical confinement enhancing their residence time in the plasma volume [29]. Consequently, plasmadroplet interactions can have a significant effect, not only on the plasma behavior (e.g., electron temperatures, plasma densities, and transport properties [30][31][32][33]), but also on the plasmadeposition process (e.g., precursor fragmentation [34], thin-film deposition rates [18,35], and degree of plasma polymerization [36,37]).…”

Pulsed-aerosol assisted low-pressure plasma for thin film deposition

“…However, it is more complex in the presence of slightly volatile liquids, liquid mixtures, liquid solutions with highly reactive molecules [27][28] or colloidal solutions [29] [30] [24]. In these cases, aerosol injection becomes an alternative [31], [32]: it consists of micrometric liquid droplets suspended in a gaseous medium that can be injected either at low or atmospheric pressure and behaved as reservoirs of neutral species.…”