Articles
Iranian Journal of Polymer Science and Technology (10163255)
Hypothesis: Metal corrosion, an inevitable and detrimental phenomenon, poses significant economic, environmental, and engineering challenges across various industries. The Polyurethane coatings, renowned for their excellent adhesion to metal surfaces, mechanical strength, and chemical resistance, have emerged as a cost-effective and efficient solution to mitigate corrosion. Recent research has focused on advancing these coatings to eliminate volatile organic compounds (VOCs), incorporate natural materials, and enhance their corrosion resistance through the integration of nanoparticles.
Methods: In this study, waterborne polyurethanes (WPUs) were initially synthesized using renewable and biocompatible castor oil as a polyol. To enhance the corrosion resistance of the prepared coatings, two waterborne PU coatings containing pristine graphene oxide (GO) nanoparticles and graphene oxide (GO) nanoparticles modified with para-tert-butylcalix[4]arene (BC4A) were prepared via in-situ polymerization method. The structural properties of the nanocomposites were characterized using ATR-FTIR, NMR, XRD, contact angle measurements, SEM, and TGA. Subsequently, the corrosion resistance of these coatings was investigated using EIS and PDS techniques.
Findings: DLS analysis confirmed the stability of the dispersions. SEM images revealed that C4A-GO nanosheets exhibited superior dispersion within the polymer matrix compared to unmodified GO nanosheets. To assess the corrosion resistance of the coatings, EIS and PDS tests were conducted. The corrosion current density (icorr) and charge transfer resistance (Rct) values for the WPU/C4A-GO sample were 8 × 10^-9 A/cm² and 629610 Ω.cm², respectively, indicating its potential as a corrosion-inhibiting filler. Overall, the in-situ synthesis of polyurethane with nanoparticles significantly enhanced the corrosion resistance of the coatings. This improvement is attributed to the incorporation of nanoparticles into the polymer matrix, the formation of cross-links within the polyurethane structure, and increased surface hydrophobicity.
An advanced, eco-friendly, and fully bio-based flame retardant (FR) system has been created and applied to the cellulose structure of the cotton fabric through a layer-by-layer coating method. This study examines the flame-retardant mechanism of protein-based and phosphorus-containing coatings to improve fire resistance. During combustion, the phosphate groups (−PO₄2−) in phosphorus containing flame retardant layers interact with the amino groups (–NH2) of protein, forming ester bonds, which results in the generation of a crosslinked network between the amino groups and the phosphate groups. This structure greatly enhances the thermal stability of the residual char, hence improving fire resistance. Cone calorimeter and flammability tests show significant improvements in fire safety, including lower peak heat release rates, reduced smoke production, and higher char residue, all contributing to better flame-retardant performance. pHRR, THR, and TSP of the flame-retarded cotton fabric demonstrated 25, 54, and 72% reduction, respectively. These findings suggest that LbL-assembled protein–phosphorus-based coatings provide a promising, sustainable solution for creating efficient flame-retardant materials. © 2025 by the authors.
The rapid development of chemical industries and oil spills during extraction and transportation have caused severe environmental pollution. Polyurethane foams “PUF” are widely used to remove oil from water due to their three-dimensional porous networks, which provide high absorption capacity. However, their effectiveness in oil/water separation applications, may decrease with repeated use as a result of structural and chemical degradation, and loss of hydrophobicity. In this research, to address this limitation and increase in their long-term stability and durability, fluorinated waterborne polyurethanes containing Fluorolink E10-H-modified nano-silica (WPU/Fl@SiO2) were synthesized and applied to coat PUFs by the dip-coating technique. This strategy offers several advantages, including low VOC emissions, a one-stage and scalable modification method, minimal material usage, and reduced time and energy consumption. The prepared nanostructures, WPU nanocomposites, and modified foams were analyzed by FTIR, XRD, TGA, DLS, FE-SEM, contact angle, and oil/solvents removal tests. The findings confirmed that the PUF/W10 sample, coated with WPU-Fl@SiO2 containing 10 wt% of nanostructures, in addition to the high surface roughness, has the highest contact angle (164.9°) and superior adsorption capacity for Xylene (42 g/g) and ethyl acetate (52 g/g). Moreover PUF/W10 sample showed an acceptable oil/water performance after 50 absorption cycles compared to unmodified and other modified foam samples The PUF/W10 sample performed well in different temperature ranges and corrosive environments, including acidic, alkaline, and strong salt solutions. Moreover, this foam displayed a continuous, efficient, and selective oil/water separation capability under a simple vacuum system. This research highlights the potential of PUFs coated with WPU-Fl@SiO2 aqueous dispersion as effective and durable materials for oil/solvent separation from water. © 2024 Elsevier B.V.
