This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect.

Organic coatings based on inhibitor loaded inorganic containers for smart corrosion inhibition are presented. The overall coating performance is strongly infl uenced by the containers as well as their inhibitor capacity, compatibility with the coating matrix, and size. The important effect of container size is described for the fi rst time in this work by investigating two types of mesoporous silica containers of different diameters: 80 and 700 nm. The coating physical properties (thickness and adhesion) are comparable for both container types. In contrast, the coating barrier properties are strongly infl uenced by the container size as assessed with electrochemical impedance spectroscopy (EIS). The incorporation of bigger containers reduces the coating resistance by a factor of two. Surprisingly, despite the similar amounts (20 wt%) of loaded inhibitor (2-mercaptobenzothiazole), different active inhibition ability is detected with the scanning vibrating electrode technique (SVET). Therefore, it is found that coatings with smaller containers exhibit better self-healing performance.

This work presents an effective anticorrosive coating for the industrially important aluminum alloy, AA2024-T3. The protective coating was designed by dispersing mesoporous silica nanocontainers, loaded with the nontoxic corrosion inhibitor, 2-mercaptobenzothiazole, in a hybrid sol-gel (SiOx/ZrOx) layer. The concentration of the embedded nanocontainers was varied (0.04-1.7 wt %) to ascertain the optimum conditions for anticorrosion performance. Attaining high efficiency was found to be a compromise between delivering sufficient corrosion inhibitor and preserving the coating barrier properties. The impact of nanocontainer concentration on the thickness and adhesion of freshly cured coatings was also investigated. The barrier properties of the intact coatings were assessed by electrochemical impedance spectroscopy. The active corrosion inhibition was evaluated during a simulated corrosion process by the scanning vibrating electrode technique. This study has led to a better understanding of the factors influencing the anticorrosion performance and properties of active anticorrosive coatings with embedded nanocontainers.

Application of mesoporous silica nanoparticles (MSNs) as delivery tools for self-healing coatings is limited by spontaneous leakage and specifically responsive release of small molecular inhibitors. In this work, a pH/sulfide ion responsive release system based on MSNs using a Cu-BTA complex forms at the openings of the mesopores into which BTA (corrosion inhibitor) and benzalkonium chloride (biocide) are loaded. The spontaneous leakage of active species is completely avoided and premature release of the loaded composition was lowered to 0.02. The responsive release begins when the pH is lower than 5 or [S^2-] is higher than 0.02 mM (about 0.6 ppm). The hybrid coating containing the responsive release system exhibits feedback self-healing property sensitive to lowering of pH and sulfide ion concentration and, at the same time, provides a high barrier level for a long time. Due to incorporation of biocide in the release system, the coating is also provided with antifouling properties

Since the first development of surfactant-templated mesoporous silicas, the underlying mechanisms behind the formation of their structures have been under debate. Here, for the first time, time-resolved small-angle neutron scattering (tr-SANS) is applied to study the complete formation of mesoporous silica nanoparticles. A distinct advantage of this technique is the ability to detect contributions from the whole system, enabling the visualization not only of particle genesis and growth but also the concurrent changes to the coexistent micelle population. In addition, using contrast-matching tr-SANS, it is possible to highlight the individual contributions from the silica and surfactant. An analysis of the data agrees well with the previously proposed "current bun" model describing particle growth: Condensing silica oligomers adsorb to micelles, reducing intermicellar repulsion and resulting in aggregation to form initial particle nuclei. From this point, the growth occurs in a cooperative manner, with condensing silica filling the gaps between further aggregating micelles. The mechanistic results are discussed with respect to different reaction conditions by changing either the concentration of the silica precursor or the temperature. In doing so the importance of in situ techniques is highlighted, in particular, tr-SANS, for mechanism elucidation in the broad field of materials science.

The present work contributes to the coating design of active anticorrosive coatings for the aluminum alloy, AA2024-T3. Part II is a continuation of Part I: Influence of Nanocontainer Concentration and describes further surprising aspects of the design of nanocontainer based active anticorrosive coatings, which influence their performance. The studied coating system consists of a passive sol-gel (SiO(x)/ZrO(x)) matrix and inhibitor (2-mercaptobenzothiazole) loaded mesoporous silica nanocontainers (MBT@NCs), which are dispersed only in half of the coating volume. Varying position and concentration of MBT@NCs the synergetic effect of inhibitor amount and path length on the metal surface were analyzed, considering the balance between optimum barrier properties, active protection and adhesion. The impact of MBT@NC position on passive and active corrosion resistance was investigated by electrochemical impedance spectroscopy and scanning vibrating electrode technique. Increasing the distance between MBT@NCs and metal surface led to better barrier properties but worse active corrosion inhibition. These findings improve the understanding of the factors influencing the overall performance of active anticorrosive coatings and enable the development of a coating system with optimum anticorrosion efficiency.

Hybrid coatings are formed by dispersing inhibitor (benzotriazole) containing functionalized mesoporous silica nanoparticles throughout a polyester primer. They outperform the primer in corrosion tests both when intact and scratched. Adding the inhibitor directly (without encapsulation into nanoparticles) is found to be less effective. Given the afforded holistic protection, these hybrid coatings represent an excellent model for future coating design.

Nanoplasmonic biosensors based on gold nanoparticle functionalized smooth silica and porous calcium carbonate particles are presented. It is identified in this comparative study the role of porosity for adsorbing gold nanoparticles and subsequent detection of biomarkers. That is further applied in this study for detection of biomarkers. Detection of glucose a biomarker of diabetes is studied together with that of bovine serum albumin a very relevant bio-molecule. Raman scattering is used for label-free detection of molecules in the sub-mu MmM range detection capabilities, which covers the range corresponding to healthy and diseased persons. Implications of current study for detection and identification of biomarkers are discussed