Due to the wide-ranging of preservative surfaces applications, there is a need for a fundamental understanding of not only how to produce such exceptional surfaces but also to know how specific surface properties affect coatings pore wettability, for example, morphology and chemical comprehending. Silica-based hybrid coatings as advanced hybrid polymers have been shown to exhibit excellent chemical stability with a chance to functionalize combined with reducing the corrosion of metal substrates. However, researches show that sol-gel only has some limitations in terms of the period of anti-corrosive properties due to the high porosity. Therefore, this work will report the preliminary performance of the diffusion prevention in a silica-based hybrid sol-gel coating that has been enhanced by adding Oleic acid (OA) to the sol-gel formula. The evaluation of the effect of the adsorption mechanism of OA on aluminium alloys surface was studied based upon using infrared analysis (FTIR) as a non-destructive test separately. The chemical confirmation of adding OA to Sol-gel was done by infrared spectroscopy (ATR-FTIR) and supported by analyzing the morphology of the surface by using scanning electron microscopy (SEM) and water contact angle test (WCA). Furthermore, the coatings' corrosion performances were studied using electrochemical impedance spectroscopy (EIS) and Potential-dynamic polarization scanning (PDPS). As a result, the Oleic acid - silica-based hybrid coating exhibited exceptional functionalized pore-blocking, hydrophobic and anti-corrosion properties, providing mimicked active protection on the aluminium alloy 2024-T3 samples compared to sol-gel-only and non-coated samples.

Zinc oxide is an active, inorganic material for a number of important applications. Zinc Oxide have wide properties for industrial applications which has been further increased by making the use of it in nanoscale size that fit in the corrosion resistant coatings. Nanoparticles have unique properties such as large surface area and nanoscale size due to which it possess various application in coatings and paints. Coating is a covering which when applied to the surface forms a layer and act as a protective barrier to the surface based on the property of the coating. Nanocomposite coatings are comparatively low cost and have more applications like dealing with the corrosion and radiation resistivity. Incorporation of nanoparticles in coating enhance its property by reducing the void and expected to induce barrier property for corrosion.

For this purpose, zinc oxide nanoparticles were synthesized using wet chemical method. The effect of reactants (base) used in ZnO synthesis was studied from pH 9 to 11 and was characterized using XRD, FT-IR, SEM-EDX, etc. To increase the hydrophobicity and to make them suitable to disperse in polymeric binder, synthesized ZnO nanoparticles, have been surface modified with different silanes such as aminopropyl triethoxy silane (APTES), hexadecyl trimethoxy silane (HDTMS) and vinyltriethoxy silane (VTES). Surface modification was examined by FTIR, TGA, SEM-EDX and Contact angle analysis and VTES was found suitable for surface modification. Surface modified ZnO nanoparticles have been dispersed in polymeric binder (liquid EPDM) with other additives to form coating formulations. These coating formulations were applied on MS panels and it was observed that developed coating formulations have good mechanical and physical properties and high corrosion resistance.

A high efficiency, low band-gap photocatalyst is presented. The platform consists of gold nanoparticles (AuNPs) confined in the pores of a silicon substrate. Careful fabrication of the pores and choice of the particles allows for a maximum of two AuNPs within a single pore, preventing agglomeration. The nanoporous substrate is produced by first, creating a mask with block copolymer templating and metal infiltration on a silicon substrate, and second, reactive ion etching to remove the silicon, which has not been masked by the template. In this work, the pores are 60 nm in depth and 25 nm in diameter and the AuNPs are 18 nm in diameter. The AuNPs’ access to the analyte, provides more active sites for redox reaction, leading to enhanced efficiency. While proximity of nanoparticles enhances coupling efficiency, confinement prevents rapid recombination of photogenerated charge carriers, a major factor contributing to low efficiency of photocatalytic materials. Degradation of methyl orange (MO) is used to determine the photocatalytic efficacy of AuNSM compared to (i) bare silicon and (ii) AuNPs randomly dispersed on silicon. After 90 minutes exposure to UV light (λ = 353 nm) in the AuNSM, the MO absorption is <1%, indicating near complete degradation, while it is still 85% and 70% for systems (i) and (ii), respectively. Finite Element Method simulations of the confined structure suggest that the AuNPs act as a mediator/receptacle for photogenerated charges rather than a source of them at this wavelength and thus enhance the performance of the photocatalyst by creating more effective Schottky junctions—preventing recombination of electrons and holes—rather than by a localised surface plasmonic resonance effect.

The interaction of polyelectrolyte-surfactant with interfaces plays a very important role in many technological fields, including cosmetics, food science or drug delivery. This has stimulated the research trying to shed light on the most fundamental aspects governing the adsorption processes and the equilibration of the interfacial layers. The current knowledge of the physico-chemistry of polyelectrolyte-surfactant systems has evidenced that in most of the cases, the association process of polyelectrolyte and surfactant molecules in the bulk is guided by non-equilibrium effects, even though the control of the mixing protocol allows obtaining reproducible aggregates (kinetically trapped-aggregates), with these non-equilibrium effects impacting decisively on their interfacial properties of polyelelectrolyte-surfactant systems. Therefore, the understanding of the interfacial processes involving polyelectrolyte-surfactant mixtures makes necessary the analysis of the association phenomena occurring in the bulk, i.e. the formation of the so-called polyelectrolyte-surfactant complexes, and their impact on the equilibration of the interface.

This work addresses the main physico-chemical aspects related to the formation of polyelectrolyte-surfactant layers at fluid interfaces, combining a careful examination of the equilibrium and rheological properties of the interfacial films with the structural and compositional information obtained using neutron reflectometry. Furthermore, the assembly of the mixtures will be correlated to the bulk association processes trying to provide a comprehensive picture describing the interfacial behavior of polyelectrolyte-surfactant mixtures at fluid interface. This requires the study of combinations of different polycations (poly(diallyldimethylammonium chloride) and chitosan) with surfactant bearing different charge (neutral, anionic and zwitterionic). Thus, it will be possible to obtain a whole perspective of the role of the association processes on the structure and properties of the interfacial layers.

In December 2019, a novel strain of coronavirus, SARS-CoV-2, was identified. Hoping to prevent transmission, many countries adopted a mandatory mask use in closed public spaces. However, most mask options display a passive-like action against COVID-19. To overcome such restrictions, this work proposes the incorporation of anti-viral essential oils (EOs) loaded onto a nanofibrous layer that can be adapted to both community and commercial masks.

Twenty EOs selected based on their antimicrobial nature were examined for the first time against the Escherichia virus MS2. The most effective were the lemongrass (LO), Niaouli (NO) and eucalyptus (ELO) with a minimum inhibitory concentration (MIC) of 356.0 mg/mL, 365.2 mg/mL and 586.0 mg/mL, respectively. Polycaprolactone (PCL) was prepared at 14 wt% in chloroform/dimethylformamide (DMF) and processed via electrospinning, with processing parameters being optimized to 23 kV, 0.7 mL/h and 26 cm. Uniform, beadless nanofibers were obtained. Mats were characterized as mechanically resilient, to endure movements arising from mask positioning, and hydrophobic in nature, to repel droplets coming from the exterior. Loading of the nanofibrous mats was accomplished via two ways: (1) physisorption and (2) by combining the EOs with the polymer solution. In both cases, EOs were loaded at 10% of MIC concentration (saturation) for 24 h. Presence of the EOs was confirmed along the mats (UV-visible). Antimicrobial testing via halo determination, verified their diffusion abilities. More importantly, time-kill kinetics testing of the loaded mats attested to the EOs capability to fight the virus MS2 even when bonded to the nanofibers at a smaller concentration than MIC. EOs-physisorbed mats were quicker in their action, while those entrapping the EOs in their polymeric matrix retained the antiviral activity of the mat for longer. Data demonstrated the potential of these EOs-loaded PCL nanofibers mats to work as COVID-19 active barriers for individual protection masks.