X-ray absorption investigation of the local structural and electronic properties of cerium doped organic-inorganic hybrid coatings

• Grant number: 16/02201-1
• Support type: Scholarships abroad - Research Internship - Doctorate
• Effective date (Start): October 01, 2016
• Effective date (End): September 28, 2017
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Peter Hammer
• Grantee: Fábio Cesar dos Santos
• Supervisor abroad: Laura Simonelli
• Home Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Local de pesquisa : ALBA Synchrotron Light Source, Spain
• Associated to the scholarship: 14/09547-5 - Study on the influence of synthesis conditions on the properties of pure and Ce(IV) modified organic-inorganic hybrids, BP.DR

Abstract

The project proposes to employ the X-ray absorption spectroscopy to investigate the relationship between structure and properties of cerium doped organic-inorganic hybrids of the siloxane-methacrylate system prepared by the sol-gel process. The main emphasis will be given on the effects of cerium (IV) doping on the formation of a hybrid network and the self-healing ability of hybrid coatings in corrosive environments. Siloxane-PMMA hybrids will be prepared from the polymerization of methyl methacrylate (MMA) and 3-(Trimethoxysilyl)propyl methacrylate (MPTS) followed by hydrolysis and condensation of tetraethylorthosilicate (TEOS). Different amounts of Ce(IV) will be added in three different stages of the hybrid synthesis: polymerization of the organic phase, inorganic hydrolysis/condensation and the final hybrid solution. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) will be applied to investigate the local structure of cerium, to access its oxidation state and to verify the formation of cerium oxides and hydroxides. The obtained results will be correlated with structural characteristics of the different hybrid matrices determined using Raman spectroscopy, and with the anticorrosive properties of the coatings, studied by electrochemical impedance spectroscopy. All results obtained upon Ce doping will be discussed in the context of structure and properties of undoped hybrid matrices, optimized using the multivariate analysis. (AU)