High protection performance based on corrosion media-consumption and barrier properties of the supramolecular polymer reinforced graphene oxide composite coatings

Halloysite clay nanotubes were investigated as a tubular container for the corrosion inhibitor benzotriazole. Halloysite is a naturally occurring cylindrical clay mineral with an internal diameter in the nanometer range and a length up to several micrometers, yielding a high-aspect-ratio hollow tube structure. Halloysite may be used as an additive in paints to produce a functional composite coating material. A maximum benzotriazole loading of 5% by weight was achieved for clay tubes of 50 nm external diameters and lumen of 15 nm. Variable release rates of the corrosion inhibitor were possible in a range between 5 and 100 h, as was demonstrated by formation of stoppers at tube openings. The anticorrosive performance of the sol-gel coating and paint loaded with 2-5% of halloysite-entrapped benzotriazole was tested on copper and on 2024-aluminum alloy by direct exposure of the metal plates to corrosive media. Kinetics of the corrosion spot formation at the coating defects was analyzed by the scanning vibrating electrode technique, and an essential damping of corrosion development was demonstrated for halloysite-loaded samples.

Hydrogels based on natural polymers have bright application prospects in biomedical fields due to their outstanding biocompatibility and biodegradability. However, the poor mechanical performances of pure natural polymer-based hydrogels greatly limit their application prospects. Recently, a variety of strategies has been applied to prepare natural polymer-based hydrogels with enhanced mechanical properties, which generally exhibit stiffening, strengthening, and stretchable behaviors. This article summarizes the recent progress of natural polymer-based hydrogels with enhanced mechanical properties. From a structure point of view, four kinds of hydrogel are reviewed; double network hydrogels, nanocomposite hydrogels, click chemistry-based hydrogels, and supramolecular hydrogels. For each typical hydrogel, its preparation, structure, and mechanical performance are introduced in detail. At the end of this article, the current challenges and future prospects of hydrogels based on natural polymers are discussed and it is pointed out that 3D printing may offer a new platform for the development of natural polymer-based hydrogels.