Wettability of Graffiti Coatings by Green Nanostructured Fluids.

Green nanostructured fluids (GNFs), specifically water-in-oil nanoemulsions (w/o NEs), were investigated as professional "brush on, wipe off" nanodetergents for the effective removal of various challenging graffiti coatings. The efficacy of the advanced nanodetergents in eradicating resilient graffiti coatings was evaluated using various methods to assess the surface properties of forming graffiti coatings. The surface properties of these coatings were examined by assessing their wettability by water, surface free energy, and topography to obtain information on the intermolecular interactions with the nanodetergent during the wetting and graffiti removal process. Our findings revealed significant variations in the coating removal rate and efficacy of green nanostructured fluids, which are stabilized using surfactants derived from saccharides or amino acids. A water-in-oil nanoemulsion, stabilized by caprylyl/capryl glucoside, demonstrated exceptional efficiency at cleaning graffiti paints based on alkyd resin and containing various additives such as nitrocellulose or bitumen, from any hard surface within a short time period. However, a w/o NE, stabilized by sodium cocoyl glycinate, also showed effective removal of graffiti paints containing durable bitumen, albeit at a slower rate on. These green nanostructured fluids can be used as specific nanodetergents for the comprehensive removal of various graffiti coatings, but require a specified action time to prevent damage to the original substrate beneath the paint coating.

Multiheaded Cationic Surfactants with Dedicated Functionalities: Design, Synthetic Strategies, Self-Assembly and Performance.

Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant's molecular structure with respect to the conventional single-head-single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.