A Comparative Study on Graphene Oxide and Carbon Nanotube Reinforcement of PMMA-Siloxane-Silica Anticorrosive Coatings

Author(s)

Harb, Samarah V. ^[1] ; Pulcinelli, Sandra H. ^[1] ; Santilli, Celso V. ^[1] ; Knowles, Kevin M. ^[2] ; Hammer, Peter ^[1]

Affiliation

^[1] UNESP Univ Estadual Paulista, Inst Quim, BR-14800060 Araraquara, SP - Brazil

^[2] Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS - England

• Document type: Journal article
• Source: ACS APPLIED MATERIALS & INTERFACES; v. 8, n. 25, p. 16339-16350, JUN 29 2016.
• Web of Science Citations: 14

Abstract

Carbon nanotubes (CNTs) and graphene oxide (GO) have been used to reinforce PMMA-siloxane-silica nanocomposites considered to be promising candidates for environmentally compliant anticorrosive coatings. The organic inorganic hybrids were prepared by benzoyl peroxide (BPO)-induced polymerization of methyl methacrylate (MMA) covalently bonded through 3-(trimethoxysilyl)propyl methacrylate (MPTS) to silica domains formed by hydrolytic condensation of tetraethoxysilane (TEOS). Single-walled carbon nanotubes and graphene oxide nanosheets were dispersed by surfactant addition and in a water/ethanol solution, respectively. These were added to PMMA-siloxane-silica hybrids at a carbon (CNT or GO) to silicon (TEOS and MPTS) molar ratio of 0.05% in two different matrices, both prepared at BPO/MMA molar ratios of 0.01 and 0.05. Atomic force microscopy and scanning electron microscopy showed very smooth, homogeneous, and defect-free surfaces of approximately 3-7 mu m thick coatings deposited onto A1020 carbon steel by dip coating. Mechanical testing and thermogravimetric analysis confirmed that both additives CNT and GO improved the scratch resistance, adhesion, wear resistance, and thermal stability of PMMA-siloxane-silica coatings. Results of electrochemical impedance spectroscopy in 3.5% NaCl solution, discussed in terms of equivalent circuits, showed that the reinforced hybrid coatings act as a very efficient anticorrosive barrier with an impedance modulus up to 1 G Omega cm(2), approximately 5 orders of magnitude higher than that of bare carbon steel. In the case of GO addition, the high corrosion resistance was maintained for more than 6 months in saline medium. These results suggest that both carbon nanostructures can be used as structural reinforcement agents, improving the thermal and mechanical resistance of high performance anticorrosive PMMA-siloxane-silica coatings and thus extending their application range to abrasive environments. (AU)

• FAPESP's process: 14/12182-9 - Mechanical analysis by nanoindentation, microscratch and wear tests of anticorrosive siloxane-PMMA hybrid coatings reinforced by carbon nanotubes and graphene
• Grantee: Samarah Vargas Harb
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 13/04314-0 - Development of siloxane-PMMA coatings reinforced by carbon nanotubes and graphene for anticorrosive applications
• Grantee: Samarah Vargas Harb
• Support Opportunities: Scholarships in Brazil - Master