The stability of interfaces between polymethyl methacrylate (PMMA) and titanium (Ti) are tested in a Ringer solution that is an aggressive medium usually used for biomaterial evaluation. The devices are PMMA-grafted/Ti elaborated via a “grafting-from” method involving three steps, the alkali activation of Ti sheets, their functionalization with an initiator of polymerization through a phosphonate anchoring group and the growth of PMMA brushes. Electrochemical characterizations demonstrate that the stability of the PMMA-grafted/Ti interface in biological medium is satisfactory and that the grafting of PMMA is even acting as a protective barrier for titanium. Indeed, PMMA-grafted/Ti remains passive in Ringer solution until at least +3 V/SCE (saturated calomel electrode), even under inflammatory conditions, while localized corrosion was measured on as-received titanium in similar conditions. This protecting role is attributed to the grafted interface, since spin-coated PMMA does not decrease the corrosion sensitivity of titanium.

In terms of current needs for renewable resources, geothermal energy is one of the future solutions for heat and electricity generation. However, geothermal plants are exposed to very aggressive media (high-temperature [HT], salt-rich fluid, etc.), leading to extensive corrosion of the metallic parts. Should the corrosion inhibitors work at HT, their injection would be mandatory to ensure the reasonable lifetime of geothermal plants. The first part of this review concerns the degradations observed in geothermal plants, which depend on the site properties and the methods for evaluating the corrosion intensity of such systems. Autoclave experiments, although rarely used for geothermal applications, maybe the most appropriate to measure the representative corrosion rate, that is, under use temperature and pressure conditions. In the second part, clues to evaluate the performance and mechanism of corrosion inhibitors are mentioned, and molecules already used to protect steel are reported. However, this review also highlights the lack of data on HT inhibitors, especially for geothermal applications, where the efficiency of a given molecule is strongly related to the real medium. Thus, the protection of new geothermal plants where HT is reached requires the search for products that are stable and efficient under such conditions.Using the heat derived from the Earth's core, geothermal energy constitutes a renewable solution for future energy. It is already widely used worldwide, especially in Europe with several sites in Iceland and in the Dogger aquifer, Paris basin. Additional sites were recently identified, for example, in Upper Rhine Graben, where the composition of the media and use temperatures may differ from the already established plants.However, due to the aggressiveness of geothermal fluids, one major issue is the reduced lifetime of geothermal plants. Indeed, the steel tubes of such | © 2022 Wiley-VCH GmbH.

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