Efficient Flame Retardant Thin Films Synthesized by Atmospheric Pressure PECVD through the High Co-deposition Rate of Hexamethyldisiloxane and Triethylphosphate on Polycarbonate and Polyamide-6 Substrates.

An innovative approach to produce high-performance and halogen-free flame-retardant thin films at atmospheric pressure is reported. PDMS-based coatings with embedded dopant-rich polyphosphates are elaborated thanks to a straightforward approach, using an atmospheric pressure dielectric barrier discharge (AP-DBD). Deposition conditions have been tailored to elaborate various thin films that can match the fire performance requirements. Morphology, chemical composition, and structure are investigated, and results show that the coatings performances are increased by taking advantage of the synergistic effect of P and Si flame retardant compounds. More specifically, this study relates the possibility to obtain flame retardant properties on PolyCarbonate and PolyAmide-6 thanks to their covering by a 5 µm thick coating, i.e. very thin films for this field of application, yet quite substantial for plasma processes. Hence, this approach enables deposition of flame retardant coatings onto different polymer substrates, providing a versatile fireproofing solution for different natures of polymer substrates. The presence of an expanded charred layer at the surface acts as a protective barrier limiting heat and mass transfer. This latter retains and consumes a part of the PC or PA-6 degradation byproducts and then minimizes the released flammable gases. It may also insulate the substrate from the flame and limit mass transfers of remaining volatile gases. Moreover, reactions in the condensed phase have also been highlighted despite the relatively thin thickness of the deposited layers. As a result of these phenomena, excellent performances are obtained, illustrated by a decrease of the peak of the heat release rate (pHRR) and an increase of the time to ignition (TTI).

Organosilicon coatings deposited in atmospheric pressure townsend discharge for gas barrier purpose: effect of substrate temperature on structure and properties.

Organosilicon plasma polymer and silicalike layers are deposited at different temperatures in a dielectric barrier discharge at atmospheric pressure operating in the Townsend regime. Final properties of these two kinds of layers can be finely tuned by the plasma process conditions. In particular, influence of deposition temperature is investigated when hexamethyldisiloxane based monolayers are deposited on poly(ethylene naphtalate) substrate. Coating chemical structure is tested by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Their thickness, topography, and mechanical properties are evaluated by ellipsometry, scanning electron microscopy observation of coatings cross sections, atomic force microscopy, and nanoscratch testing. Permeability of coated polymer is measured for transparent silicalike layers, and the effect of coating structure on the oxygen gas permeability is discussed. The deposition temperature of coatings at 90 °C provides a strong improvement in barrier property compared to room temperature deposition, thanks to a densification of the SiO2 matrix and to a decrease in the silanol group content.

Ultrasmooth silver thin film electrodes with high polar liquid wettability for OLED microcavity application.

For a lab-on-chip application, we fabricate a blue bottom emitting strong microcavity organic light emitting diode (OLED), using very smooth and optically thin (25 nm) silver film as anode on a glass substrate. To improve the hole injection in the OLED device, PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid)) has been used, so the silver anode must present not only a very smooth surface but also a strong adherence on the glass and a high wettability to allow a good PEDOT-PSS spin coating deposition. To obtain these physical properties, different 5 nm thick nucleation layers (germanium, chromium, and hydrogenated amorphous carbon) have been used to grow the silver thin films by e-beam deposition. The Ge/Ag bilayer presents all the desired properties: this bilayer, investigated by ellipsometry, optical profilometry, contact angle measurements, and XPS analysis, highlights an ultrasmooth surface correlated with the film growth mode and a high wettability related to its surface chemical composition.