Synthesis and controlled release kinetics of pH-sensitive hollow polyaniline microspheres encapsuled with the corrosion inhibitor

Constructing chitosan microcapsules using hydroxypropyl methylcellulose for self-healing antibacterial wood coating

This study presents the development of a multifunctional, smart wood coating incorporating advanced micro-nano technologies to achieve self-healing, antibacterial, and pH-responsive properties. Chitosan, known for its biocompatibility and biodegradability, was combined with lipophilic TiO₂ and hydroxypropyl methylcellulose (HPMC) as wall materials, while wood wax oil served as the core material to synthesize microcapsules. These microcapsules were integrated into a UV-cured coating. The results indicated that microcapsules formulated with 20.0 % lipophilic TiO₂ and 40.0 % HPMC exhibited the highest encapsulation efficiency and yield, along with enhanced thermal stability and prolonged release. When applied to Fagus sylvatica wood at microcapsule mass fraction of 2.0, 5.0, 8.0 and 10.0 %, the coating effectively repaired simulated blade damage within six days, achieving a recovery rate of 69.04 % with the microcapsule mass fraction is 2.0 %. This formulation also demonstrated strong antibacterial activity, with inhibition rates of 92.0 % against Escherichia coli (E. coli) and 75.82 % against Staphylococcus aureus (S. aureus). When the mass fraction of microcapsules is 2.0 %, the comprehensive performance of the coating is optimal. These findings highlight the potential of this dual-functional, self-healing, and antibacterial wood coating, offering promising directions for advancing multifunctional wood surface technologies.

3-APTES on Dendritic Fibrous Mesoporous Silica Nanoparticles for the pH-Controlled Release of Corrosion Inhibitors

Mesoporous silica nanoparticles (MSNPs) are currently used in different fields like catalysis, nanomedicine, and conservation science, taking advantage of their high surface area. Here, we synthesized and functionalized mesoporous dendritic fibrous nanoparticles to realize a smart delivery system of protective agents for metals. Different MSNPs were obtained via the microemulsion method followed by a hydrothermal or refluxing treatment at different w/o ratios, times, and temperatures. Dendritic spherical silica nanoparticles with specific features such as an appropriate size (450 nm), a very large surface area (600 m2 g-1), and a high yield synthesis (86%) were selected for surface modification. The fiber surface of the selected MSNPs was functionalized with 3-aminopropyl triethoxysilane (3-APTES). 3-APTES works as a pH-driven "nanogate", suppressing the immediate leakage of the total guest molecule load and modulating the release as a function of pH conditions. Surface-modified MSNPs were tested as a reservoir of the most diffused corrosion inhibitors: Mercaptobenzothiazole (MBT) and 1H-Benzotriazole (BTA); their release properties were studied in solutions with pH = 4 and 7. Functionalized and non-functionalized MSNPs showed a good loading efficiency of guest molecules (34-64%) and a pH-dependent release of the corrosion inhibitors on a timescale of several hours.

Designing Smart Microcapsules with Natural Polyelectrolytes to Improve Self-Healing Performance for Water-Based Polyurethane Coatings

Active anticorrosive organic coatings adopting microcapsules (MCs) have lately attracted extensive attention as they were proven to be effective to minimize metal corrosions and offer a long-lasting protection performance. Herein, a novel environmental-friendly active corrosion protection system was designed for aluminum alloy 2024 (AA2024) based on water-based polyurethane coatings with the addition of water and alkaline pH-responsive smart MCs, which is fabricated by utilizing 2-mercaptobenzothiazole (2-MBT) as an inhibitor, halloysite clay nanotubes (HNTs) as an inhibitor carrier, and the natural polyelectrolytes ε-poly-l-lysine (ε-PLL) and sodium alginate (SA) as layer-by-layer (LBL) encapsulation polyelectrolytes. Salt spray tests and electrochemical measurements prove that the scratched coatings with embedded MCs possess an excellent self-healing performance by forming an adsorption layer of released 2-MBT on the AA2024 surface, thereby providing over 90% inhibition efficiency within 6 days' immersion. The UV-vis spectrophotometer results further showed that the release of 2-MBT is a three-stage long-term process sensitive to water and alkaline pH value, while the outward release rate is both regulated by the solubility of 2-MBT and the SA layer. The fabricated MCs not only offer a great promise to provide an excellent self-healing performance but also shed light on the future design of advanced MCs on demand based on the LBL technique.