Structure and properties of epoxy-siloxane-silica nanocomposite coatings for corrosion protection

• Autor(a) principal: Torrico, Ruben F.A.O. [UNESP]
• Data de Publicação: 2018
• Outros Autores: Harb, Samarah V. [UNESP], Trentin, Andressa [UNESP], Uvida, Mayara C. [UNESP], Pulcinelli, Sandra H. [UNESP], Santilli, Celso V. [UNESP], Hammer, Peter [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.jcis.2017.11.069; http://hdl.handle.net/11449/179403
• topic: Corrosion protection; Multifunctional coatings; Organic-inorganic hybrid; Sol-gel process; Structural properties

Hypothesis The fraction of the silica/siloxane phase is a crucial parameter, which determines the structure and thus the properties of epoxy-siloxane-silica hybrid coatings. A careful adjustment of the colloidal precursor formulation allows tuning the nanostructure towards a highly condensed and cross-linked hybrid nanocomposite, suitable as an efficient anticorrosive coating. Experiments Novel epoxy-siloxane-silica hybrids have been prepared through the curing reaction of poly(bisphenol A-co-epichlorohydrin) (DGEBA) with diethyltriamine (DETA) and (3-glycidoxypropyl)methyltriethoxysilane (GPTMS), followed by hydrolytic condensation of tetraethoxysilane (TEOS) and GPTMS. At a constant proportion of the organic phase, the effects of the varying molar proportions of siloxane (GPTMS) and silica (TEOS) on the film properties have been investigated. Findings A detailed structural analysis suggests for intermediate TEOS to GPTMS ratios a structure of highly condensed silica-siloxane domains covalently bonded to the embedding epoxy phase. The homogeneous distribution of the quasi-spherical sub-nonmetric silica-siloxane nodes is in agreement with low surface roughness (<5 nm), observed by atomic force microscopy. This dense nanostructure results in high thermal stability (>300 °C), strong adhesion to steel substrate and excellent barrier property in saline solution, with corrosion resistance in the GΩ cm2 range.