Table 2.

The most relevant review manuscripts focused on OIH sol–gel materials published in the last few years.

Year	Reference	Discussed subject matter
2016	[183]	Principles and morphologies of microcapsules, purpose of microencapsulation,physical, and chemical techniques and healing mechanisms for the coating industry were debated.
	[184]	The progress made in the synthesis of several sol–gel-derived materials was reviewed. The main achievements in the field of anticorrosion coatings were also debated.
	[37]	Summary of the main research achievements in the development, of OIH sol–gel coatings for corrosion mitigation of steel and aluminum substrates.
	[185]	The general features of OIH coatings, and recent developments were summarized.
	[137]	Summary of the latest achievements and strategies for the sol–gel process parameters and other factors that influence the corrosion properties of the OIH coatings for corrosion protection of aluminum-based alloys.
	[20]	Overview of sol–gel technology where the fabric functions that can be achieved by this technology are debated including anticorrosion coatings.
2017	[186]	Advances in smart coatings, including OIH coatings, with response to different stimuli and damage modes were reviewed. Emphasis was on corrosion sensing, self-cleaning, anti-fouling, and self-healing polymeric coating systems.
	[187]	Recent applications using PDMS polymers for anticorrosion, anti-biofouling, anti-icing, flame-resistant and self-cleaning, anti-reflection were reviewed.
	[188]	Overview of the superhydrophobic coatings (including OIH sol–gel) reported in literature for steel protection and their performances.
2018	[138]	Different solutions for slow down the corrosion processes of metallic substrates by using the oxides and doped oxides obtained by the sol–gel method were discussed.
	[189]	Analysis of some of the most representative examples of the application of electrochemical techniques such as EIS, PDP; SVET, SIET, SKP and LEIS to determine the exact mechanism of protection offered by sol–gel coatings on metallic substrates.
	[78]	Description of the historical perception of OIH material science. The major periods linked to the genesis of OIH materials were discussed.
2019	[190]	The main aspects of the use of silicon polymers for coatings were debated. The advantages and disadvantages of these materials, and the processing methods developed were discussed.