Synthesis and surface properties of semi-interpenetrating fluorine-containing polyacrylate and epoxy resin networks

Structural Properties of Epoxy–Silica Barrier Coatings for Corrosion Protection of Reinforcing Steel

Reinforcement steel extensively applied in civil construction is susceptible to corrosion due to the carbonation process in reinforced concrete and chloride ions diffusion. Epoxy-silica-based coatings are a promising option to guarantee the long-term stability of reinforced concrete structures. In this study, the influence of the proportion between the poly (bisphenol-A-co-epichlorhydrin) resin (DGEBA) and the curing agent diethylenetriamine (DETA) on the structural, morphological, and barrier properties of epoxy–silica nanocomposites were evaluated. To simulate different stages of concrete aging, electrochemical impedance spectroscopy (EIS) assays were performed for coated samples in a 3.5 wt.% NaCl solution (pH 7) and in simulated concrete pore solutions (SCPS), which represent the hydration environment in fresh concrete (SCPS1, pH 8) and after carbonation (SCPS2, pH 14). The results showed that coatings with an intermediate DETA to DGEBA ratio of 0.4, presented the best long-term corrosion protection with a low-frequency impedance modulus of up to 3.8 GΩ cm2 in NaCl and SCPS1 solutions. Small-angle X-ray scattering and atomic force microscopy analysis revealed that the best performance observed for the intermediate DETA proportion is associated with the presence of larger silica nanodomains, which act as a filler in the cross-linked epoxy matrix, thus favoring the formation of an efficient diffusion barrier.

Antibody Micropatterned Lubricant-Infused Biosensors Enable Sub-Picogram Immunofluorescence Detection of Interleukin 6 in Human Whole Plasma

Recent studies have shown a correlation between elevated interleukin 6 (IL-6) concentrations and the risk of respiratory failure in COVID-19 patients. Therefore, detection of IL-6 at low concentrations permits early diagnosis of worst-case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL-6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL^-1 . The sensitivity of the developed lubricant-infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL-6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy-based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant-infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.

Superhydrophobic and flame retardant cotton modified with DOPO and fluorine-silicon-containing crosslinked polymer

Modification of cotton fabric to achieve superhydrophobic, self-cleaning and heat resistance is of particular interest for practical applications. Herein, a simple surface modification route is designed to introduce flame retardant component 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and low surface energy crosslinked polymer network comprising both fluorine and silicon elements on the surface of cotton fabric. The modified cotton fabric shows characteristic of superhydrophobic property with water contact angle of 154.8°, and exhibits promising self-cleaning performance. With the characters of hydrophobicity and lipophilicity, the modified cotton fabric can efficiently separate oil-water mixture and even emulsion. Moreover, the introduction of DOPO and fluorine-silicon-containing coating not only enhances the heat resistance of cotton, but also improves the flame retardant property.