Particular types of oih materials have also been

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Particular types of OIH materials have also been named, either as ORMOSILs (acronym generated from ORganically MOdified SILicates) or OMOCERs (from ORganically MOdified CERamics) depending on the precursors used (Table 1 ) and synthesis method. The most effective approach in the production of OIH materials seems to be the sol–gel technique with its specific ability to create a spacious network (mac- romolecular network) containing M–O bonds under mild (room temperature) synthesis conditions either with or without a solvent. 21 , 38 Their properties are highly dependent on the degree of mutual phase dispersion (therefore dependent on the organic/inor- ganic ratio), the reactivity of crosslinking alkoxide reagents, the processing steps, and the solvents. 39 The presence of polymeric chains within the OIH matrix contributes to the material’s high electrical resistivity and impermeability, providing similar properties to the usual painting materials. The hybrid structure maximizes the preparation of materials that could lead to efficient coatings against corrosion as wellas ensuring primary technological needs. 40 Over time, several review papers have been period- ically published about OIH gels, giving an up-to-date description of state of the art contributions. The most important reviews published since 2000 are listed chronologically in Table 2 . M O R1 O R1 O O O M M O O O R1 R1 R1 H R1 O R1 O R1 O R1 R1 N (M represents a network–forming element such as Si, Ti, Zr, Al, B, etc. R 1 is typically an alkyl group) Fig. 7: Organic–inorganic interactions for OIHs class III (adapted from Prado et al. 21 ) 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 Years 0 880 1760 2640 3520 4400 Number of publications Fig. 8: Bar chart of scientific publications published from 1990 until 2013 found in Science Direct, Springerlink, ECS Digital Library, and ACS Publications using the key words ‘‘organic–inorganic hybrids’’ J. Coat. Technol. Res.
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In the nineties, 53 the OIH concept firmly emerged and an increased number of papers focusing on this area were published within a short period of time. In 2001, several important review papers on this subject were published. Schottner 54 and Walcarius 55 reviewed the perspectives of the hybrid sol–gel-derived polymers and reported the applications of OIH materials in the various fields of electrochemistry. Mitzi 56 selected examples of OIH films and discussed the techniques used on the deposition of OIH sol–gel materials. Several authors focused review papers on aspects related with gel synthesis processes, like Hay and Raval 57 who reported on the use of the nonhydrolytic sol–gel route to synthesize OIHs. Arkhireeva et al. 58 synthesized in 2004 OIHs using both the hydrolytic and nonhydrolytic sol–gel routes. The authors showed that both routes produced OIHs. However, an improved control of the shape and particle size was obtained using the hydrolytic process. In the same year, Castelvetro et al.
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  • 1984, oIh, OIH coatings

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