Polyelectrolyte-modified layered double hydroxide nanocontainers as vehicles for combined inhibitors

Abstract

Forsyth and co-workers reported studies on combination of rare earth metallic element with a multifunctional organic component to achieve synergistic corrosion protection of AA2024. 24,25 Recently, Kallip and co-workers reported the synergistic inhibition of galvanically coupled Ze + Fe metals, when 1,2,3-benzotriazole and Ce(NO 3 ) 3 were combined. 26One topic that has not yet been covered in detail is the co-intercalation of different corrosion inhibitors within the same carrier. The incorporation of MBT in cerium molybdate hollow nanospheres were found to render corrosion protection to galvanized steel substrates when combined in coatings with LDH-MBT. 12 In this case, authors suggested that the inhibiting effect could be associated with MBT, as well as to dissolution of cerium and molybdate ions from the nanospheres under acidic conditions. Very recently, Ferrer and co-workers reported the preparation of NaY zeolites with cerium and diethyldithiocarbamate corrosion inhibitors, investigating the effect of this double-doped zeolite for corrosion protection of AA2024 alloy.27 Positive results were obtained with the zeolites in solution and when added to sol-gel coatings. Apart from these works, not much has been done in the co-intercalation of corrosion inhibitors.In this paper we go beyond mono-, towards multiintercalation and release of corrosion inhibitors in a controlled manner (Scheme 1). The strategy followed consists of using a system well known for its intrinsic controlled release mechanism (LDHs), modifying its surface with polyelectrolytes by the Layer-by-Layer (LbL) technique. The use of polyelectrolytes allows the intercalation of additional corrosion inhibitors between layers, which can be released due to pHdependent permeability of polyelectrolytes. 28,29The objective of this work is to investigate Zn-Al LDHs as containers for two corrosion inhibitors simultaneously. 2-mercaptobenthiazole (MBT), a well-known corrosion inhibitor for AA2024, 30 was intercalated in interlayer of the LDH structure by anion-exchange according to a procedure described in the literature, 31 while Ce 3+ , also known as an effective corrosion inhibitor for AA2024, 32 was adsorbed between polyelectrolyte layers on the surface of LDH-MBT platelets. The modied LDH particles (LDH-Mod) were characterized by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). Furthermore, the inuence of LDH surface modication in the release of MBT was investigated by UV-visible spectrophotometry and correlated with electrochemical studies by DC polarization and electrochemical impedance spectroscopy (EIS), in solution and as additives to a hybrid sol-gel coating. Experimental MaterialsAll the chemicals were obtained from Aldrich, Fluka, and Riedel-de Haen, with $98% of ground substance, and used as received. AA2024-T3 with the following composition was used: Cu 3.8-4.9%, Mg 1.2-1.8%, Mn 0.3-0.9%, Fe 0.5%, Si 0.5%, Zn 0.25%, Ti 0.15%, Cr 0.1%, other 0.15%, balance Al. All the alloy pane...

Antimicrobial activity of 2-mercaptobenzothiazole released from environmentally friendly nanostructured layered double hydroxides

“…and are in agreement with previously reported publications from our group for these LDH compositions (Carneiro et al . ). The XRD pattern of LDH loaded with nitrate anions shows peaks at low 2θ angles (≈10°, 20°, 30°) corresponding to (00 l ) reflections ( d = 0·90 nm).…”

“…; Carneiro et al . ). The process is divided into two main steps: synthesis of LDHs intercalated with easily displaceable nitrate ions (LDH‐NO 3 ), followed by anion‐exchange reaction with a concentrated solution of 2‐MBT, a well‐known corrosion inhibitor with biocidal properties (Poznyak et al .…”

“…The synthesis of LDHs intercalated with MBT is described elsewhere (Poznyak et al 2009;Carneiro et al 2015). The process is divided into two main steps: synthesis of LDHs intercalated with easily displaceable nitrate ions (LDH-NO 3 ), followed by anion-exchange reaction with a concentrated solution of 2-MBT, a well-known corrosion inhibitor with biocidal properties (Poznyak et al 2009;Carneiro et al 2015;Maia et al 2015).…”

Inhibition of Steel Corrosion and Alkaline Zinc Oxide Dissolution by Dicarboxylate Bola-Amphiphiles: Self-Assembly Supersedes Host-Guest Conception

“…1) have been tested as a conversion coating on galvanized steel 15 and with intercalated corrosion inhibitor as a hybrid filler in an organic coating on AA2024-T3 aluminum alloy 16 . Predominantly tested on aluminum alloys, numerous further systems have been described 17 , including direct growth of an LDH surface layer on copper-rich domains 18 , synergistic inhibitor types 19 and -amino acid interleaved LDH for environmentally friendly inhibition 20 .

Figure 1( a ) Sketch of LDH platelets with intercalated sherical anions (hydrogens are omitted for clarity). ( b ) Formulae of bola-amphiphiles b-HBA and b-PES with octenyl groups “R1” as well as non-bola type polyester PES-NB (cf.

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Smart Nanocontainers: Preparation, Loading/Release Processes and Applications

“…Regarding the nanostructures, nanocontainer can be divided into 3 main groups including: i) nanoparticles based nanomaterials (three-dimensional nanostructure) [1][2][3][4], ii) nanotubes (one dimension) [5][6][7][8], and iii) nanolayers based nanomaterials (two-dimensional nanostructure) [9][10][11]. Similarly, in terms of synthetic materials, nanocontainers consist of organic or inorganic scaffolds in which the encapsulation of active substances has been carried out.…”