Corrosion Resistance of Epoxy Coatings Modified by Bis-Silane Prepolymer on Aluminum Alloy

In this communication, a bis-silane prepolymer was used to modify epoxy resin, aiming to enhance the corrosion resistance of epoxy coatings on aluminum alloy substrates. The bis-silane prepolymer was prepared by tetraethoxysilane (TEOS) and γ-glycidoxypropyl trimethoxysilane (GPTMS). The corrosion behavior of silane-epoxy coatings was studied. Compared with silane monomer-modified epoxy coatings, bis-silane-modified epoxy coatings have lower coating capacitance (Cc), higher charge transfer resistances (Rdl), and lower double layer capacitance (Cdl) during long-time immersion. It indicates that bis-silane-modified epoxy coating has stronger waterproof permeability and substrate corrosion protection ability. In addition, due to the leaching of the silane component and cross-linking reaction between different silanes during the immersion process, the bis-silane-modified epoxy coatings exhibit much stronger “self-healing” ability.

Engineering of super bactericidal cotton using pyridinium/di-N-chloramine siloxane with intensified synergism

Tuning the ratio of complementary biocidal groups in a composite unit is proved to be a tactic to better minimize their weaknesses to realize higher synergism. A silane monomer, 6-(pyridin-4-yl)-3-(3-(trimethoxysilyl)propyl)-1,3,5-triazinane-2,4-dione, with biocidal precursors of one pyridinium and two N-chloramine sites was synthesized, hydrolyzed and dehydrocondensed on cotton cellulose. Specially, isonicotinaldehyde was ammonolyzed with biuret to produce 6-(pyridin-4-yl)-1,3,5-triazinane-2,4-dione that subsequently reacted with (γ-chloropropyl)trimethoxysilane to synthesize the silane monomer through nucleophilic substitution. The modifier on cotton was quaternized and chlorinated to transform the one pyridine and two amide N−H structures in each unit of the silicone to pyridinium and N-chloramine counterparts. The cationic pyridinium increases the hydrophilicity of the unit and electrically draws anionic bacteria to its two adjacent highly fatal N-chloramine sites, achieving a faster contact-killing rate than not only monofunctionality but also basic synergistic integration of one cationic center and one N-chloramine. This phenomenon is therefore referred to as “intensified synergism” and provides crucial information for the design of more powerful biocides. The pyridinium/di-N-chloramine silicone coating exhibited extraordinary durability towards UV irradiation, washing cycles and long-term storage due to the good UV resistance and chemical inertness of pyridinium and silicone backbone.

Vinyltrimethoxy Silane and Aminopropyl Triethoxysilane: Excellent Silane Coupling Agents for Cotton Fiber Functionalization

Vinyltrimethoxy silane and aminopropyl triethoxysilane were used for surface functionalization to enhance the textile performance of cotton. The process was carried out in an ethanol-water medium, which accelerated the cross-linking reaction between fiber and silane monomers. The process was optimized carefully as a function of fiber weight gain. The optimized modification conditions were silane monomer concentration 600 and 300% (on weight of fiber), ethanol-water ratio 60:40 and 80:20, pH 3.5 and 5, reaction time 90 and 60 min at room temperature (30°C), for VTMS and APTES, respectively. The silane-modified cotton fiber showed improved tensile strength, water repellency, thermal stability and wrinkle recovery. These improvements are due to flexibility of the Si-O bond and the fiber matrix interfacial strength properties. Instrumental analyses, such as FTIR, TGA, DTG, SEM and EDX, were carried out successfully. FTIR was used to identify the Si-O-Si group of VTMS and the Si-O-CH3 of APTES on modified cotton fibers, and TGA and DTG were used to evaluate the modification's effect on the thermal stability of the fiber. SEM was used to study the surface morphology after modification and EDX was used to measure the quantity of elemental silicon atoms on the fiber backbone. Finally, unmodified and silane-modified cotton fibers were dyed with two reactive dyes and the modified cotton fiber showed better ability to accept dye than that of the unmodified fiber.

Synthesis of Poly(methyl methacrylate-co-butyl acrylate)/Perfluorosilyl Methacrylate Core-Shell Nanoparticles: Novel Approach for Optimization of Coating Process

In this study, the coating order of two monomers in the shell polymerization process of core-shell nanoparticles was altered to facilitate easy coating and optimize the properties of the coated surface to simplify the additional coating formulation process. To obtain a glass transition temperature suitable for coating, a core was synthesized by the copolymerization of an acryl monomer. A perfluoro monomer and silane monomer were additionally added to synthesize nanoparticles exhibiting both water–oil repellency and anchoring properties. In order to realize various surface properties, the nanoparticles underwent surface modification and cellulose fiber was introduced. Through the various data described in this text, the surface properties improved with the order of the introduction of the two monomers.

Synthesis of Poly (Methyl Methacrylate-Co-Butyl Acrylate)/Perfluorosilyl Methacrylate Core–Shell Nanoparticles: Novel Approach for Optimization of Coating Process

In this study, the coating order of two monomers in the shell polymerization process of core–shell nanoparticles was altered to facilitate easy coating and optimize the properties of the coated surface to simplify the additional coating formulation process. To obtain a glass transition temperature suitable for coating, a core was synthesized by the copolymerization of an acryl monomer. A perfluoro monomer and silane monomer were additionally added to synthesize nanoparticles exhibiting both water–oil repellency and anchoring properties. In order to realize various surface properties, the nanoparticles underwent surface modification and cellulose fiber was introduced. Through the various data described in this text, the surface properties improved with the order of introduction of the two monomers.

From a silane monomer to anisotropic buckled silica nanospheres: a polymer-mediated, solvent-free and one-pot synthesis

Silica nanospheres with surface buckling and NO releasing properties are efficiently synthesized using a one-step, polymer-assisted, and solvent-free approach.

Effect of Octyl-Triethoxysilane Emulsion on Protection of Concrete

In this study, octyl-triethoxysilane emulsion was prepared using octyl-triethoxysilane monomer. The protective effect of the silane monomer and emulsion was investigated on the concrete with different water to cement ratios (0.4 and 0.5). The results showed that octyl-triethoxysilane emulsion displayed efficient protection of concrete. Octyl-triethoxysilane emulsion acquired excellent penetration depth (> 3.7 mm), the water absorption coefficient was reduced by 83.4%, and the chloride ion diffusion coefficient was only 1.8 × 10−12 m2 s−1, reduced by 71.3%. The emulsion also showed good resistance to carbonization and freezing-thawing. The carbonation depth of concrete was reduced by 42%, while the silane monomer has little effect on carbonization. Good protection performance was obtained in the freezing-thawing cycle tests. The relative dynamic elastic modulus was increased by 27%; the mass loss was reduced by 49% after 300 cycles. The protective effect of silane emulsion was also related with the water cement ratio of concrete and the test method. Silane monomer had good waterproof effect and chloride resistance, but poor resistance to carbonization and freezing-thawing. Silane emulsion was a better choice for concrete protection, for it displayed lower rate of volatilization, insignificant toxicity, and better retainment of the active ingredient.