HEALTHYGLASS

HEALTHYGLASS will determine innovative, thermally activated chemical vapor deposition (CVD) processes of amorphous silicon oxide (SiO2) oxynitrides (SiOxNy) and oxycarbides (SiOxCy) on the internal surface of pharmaceutic vials, and will define their appropriate composition and structural characteristics in order to obtain efficient and sustainable barrier properties. The targeted function of these coatings is to limit the interaction between the stored drug and the glass vial, and thus allow to new advanced pharmaceutic molecules, especially in oncology, which are sensitive or aggressive towards the glass, to be commercialized. The generated innovation by the project in terms of materials solutions and deposition processes will thus allow pharmaceutic companies to dispose of high tech, chemical resistant vials, whose internal coating can be adapted to the characteristics of the stored drugs. There is limited information in the literature on the deposition of SiO2, SiOxNy and SiOxCy films with respect to the specifications defined by the project, namely atmospheric pressure and moderate deposition temperature (<570 °C), leading to dense and chemically inert films deposited on confined surfaces at high growth rate. The project team has recently tuned a deposition process of SiO2 at the internal surface of vials from mixtures of tetraethyl orthosilicate (TEOS) and oxygen. However, these films presented insufficient corrosion resistance in severe tests recommended by the US Pharmacopeia. In the frame of this project SiO2, SiOxNy and SiOxCy will be processed from TEOS and O3 based chemical systems including reactive compounds which activate radical mechanisms to enrich the films with nitrogen and carbon. CVD of SiO2 will be first investigated as starting point prior focusing on SiOxNy and SiOxCy which present remarkable barrier properties due to the densification of the network obtained from the partial replacement of O anions by highly coordinated N and C ones. State of the art protocols for the physico-chemical, structural and mechanical characterization, including microscopy, ellipsometry, nuclear and vibrational spectroscopies, atom probe tomography and nanomechanics tests, will provide information on these complex systems, including their surface and their interface with the glass substrate. The quantification of the connectivity of the silicate network, the structural disorder, the distortion of the Si environment, and the distribution of the oxynitrides and oxycarbide species will be monitored by solid state 29Si and 13C NMR, combined with XPS and µ-FTIR. High resolution 1H NMR and the very recent and challenging Dynamic Nuclear Polarization will reveal the hydrated species which are present on or by the surface. The hydrolytic resistance and the durability of the coatings will be evaluated by sterilization cycles preconized by the European and US Pharmacopeias. The most promising coatings will be tested in more severe conditions, e.g. ageing over a period of several weeks in basic and acid pH solutions. The releasing and corrosion mechanisms will be investigated and correlations among process conditions, structure and barrier properties will be established. HEALTHYGLASS will establish process/structure/properties/performance correlations which will lead to outstanding progress at fundamental level and will pave the way towards the application of these multifunctional and durable materials in complementary sectors concerned by the functionalization of complex surfaces such as micro- and nano-electronics, plastics, medical devices and implants, or gas sensors.