A Novel Hybrid Polymer Network for Efficient Anticorrosive and Antibacterial Coatings

Difunctional Silicon Dioxide Combined with Graphene Oxide Nanocomposite to Enhance the Anticorrosion Performance of Epoxy Coatings

The nanocomposite BTA-SiO₂-GO was fabricated for the purpose of metal corrosion protection. Herein, the BTA-loaded mesoporous silica nanocontainers were prepared through a facile one-step synthetic method. Subsequently, graphene oxide (GO) was combined with the resultant BTA-SiO₂ compound because GO had a superior barrier property and impermeability. We must note that the double functional groups exist on SiO₂. Benzotriazole (BTA), as an inhibitor, can be loaded into the nanocontainer and GO can also be modified by it, resulting in excellent dispersion in epoxy coatings, which were conducive to enhancing its anticorrosion performance. In this way, the nanocomposite endows the coating system with both self-healing and physical barrier abilities. The EIS results indicated that the impedance value of the BTA-SiO₂-GO composite coatings was up to 1.2 × 10⁹ Ω cm², which indicated excellent corrosion resistant properties.

New Mussel Inspired Polydopamine-Like Silica-Based Material for Dye Adsorption

A straightforward and economic procedure has been developed for the synthesis of a new polydopamine-like silica-based material that has been obtained by oxidation of catechol with KIO4 followed by reaction with 3-aminopropyltrimethoxysilane. All techniques adopted for characterization showed that the obtained material is rich in different functional groups and the morphological analyses revealed dimensions in the nanometric range. The hybrid material has been characterized by several techniques showing its polydopamine-like nature, and preliminary observations for dye adsorption have been reported.

Heparin Immobilized on Multiwalled Carbon Nanotubes for Catalytic Conversion of Fructose in Water with High Yield and Selectivity

Being a member of the glycosaminoglycan family of carbohydrates, native heparin is a highly sulfated polysaccharide. Herein, heparin was grafted onto polydopamine (PDA)- and poly(ethylene imine) (PEI)-coated multiwalled carbon nanotubes (MWCNTs) (heparin-PEI@PDA@MWCNT). The immobilized heparin consists of a sulfated repeating disaccharide unit, conferring a unique microenvironment when catalyzing fructose dehydration into 5-hydroxymethylfurfural (HMF). The hydrogen bonding interactions naturally occur between the disaccharide unit of heparin and the monosaccharide fructose, and the adjacent sulfonic acid groups catalyze the fructose dehydration. The reactions were performed in water, and heparin-PEI@PDA@MWCNT achieved an HMF yield of 46.2% and an HMF selectivity of 82.2%. For the dehydration of fructose in water, heparin-PEI@PDA@MWCNT exhibits advantages over published heterogeneous catalysts on the basis of HMF yield and HMF selectivity. Three aspects contribute to the environmentally benign processing: (1) the catalyst heparin is a natural sulfated polysaccharide; (2) the catalysis is carried out in water and not in organic solvents; and (3) fructose can be produced from a biomass resource.

Detection of in Situ Early Corrosion on Polymer-Coated Metal Substrates

Protective coating systems (PCS) are a common and facile method to protect metal substrates from corrosion. The corrosion control performance of polymer-coated metal substrates is still predominantly evaluated by visual assessment. Unfortunately, for many decades, PCS material development and performance testing has basically been a complicated process of waiting to determine which coating, in relative terms, allows corrosion to occur first from an intentionally created breach through the coating. This type of testing provides only relative ratings between PCS performance. Electrochemical methods, such as electrochemical impedance spectroscopy, each have caveats and pitfalls for qualifying or quantifying polymer-coated metal substrates. When these data are studied carefully, these measurements result in many false positive and false negative results compared with real environmental testing and the paths to failure vary dramatically. The critical issue is that these methods do not result in a scientific basis for understanding either the pathway(s) or progressive milestones toward diminished PCS performance, failure, and the loss of substrate structural integrity for coated substrates. Data supports that ultimately all PCS fail to provide the necessary substrate protection. However, to make substantive gains, scientists and engineers require a rational basis to design, engineer, test, quantify, and/or estimate service life and remaining service life and repair future generations of PCS. Our research goal was to establish a quantifiable characterization protocol (CP) that directly detected, monitored, and ideally quantified the pathway(s) and important milestones of PCS corrosion spatially and temporally, with or without defects which related with testing and assessment variables regardless of environmental severity (real, laboratory, or accelerated). We report herein the CP and the results from an embedded pH-sensitive "turn-on" fluorescent probe blended with a simplified thermoplastic model PCS. The results support that the average-localized macroscopic pH is detected and tracked, and these "molecular titrations" result in values consistent with literature pH citations for premacroscopic corrosion processes, that is, before delamination and a detectable breach. The CP results are an improvement over visual corrosion detection and yet proportional to the steel substrate corrosion. The CP results deliver extreme early detection (within minutes), spatial and temporal tracking, and potentially quantifiable performance differences for the pathways and milestones toward failure of coated substrates with validated sensitivity to variables such as defect versus defect-free films, blending solvent type(s) influence, differences from varied degrees of annealing relative to T_g (thermoplastic films), substrate topography, and preparation differences. The CP utilizes small sample areas (25 mm spheres) and gathers data in a manner designed to improve statistical relevancy, provide results within short timeframes using real-time testing, diminish materials-testing timelines, and connect results with laboratory, accelerated, and real environmental severity differences. The results support that the CP directly measured the earliest possible in situ corrosion processes using defect and defect-free simplified model PCS.