ENGINEERING TECHNOLOGY

New advances in underwater adaptively enhanced adhesives


Wet adhesion plays an important role in areas such as mechanical engineering, marine technology and medical science. However, in the process of solid-solid interface water-containing bonding, the presence of water molecules can easily lead to bonding failure, mainly because the interface water hinders the contact between the adhesive and the substrate and the formation of intermolecular interactions. For the removal of interface water, researchers have made various attempts, such as interface water absorption, hydrophobic repulsion and extrusion, but these methods can not achieve complete removal of interface water, and it is difficult to ensure high-performance adhesion of the interface.

Recently, the research team of Zhou Feng, State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, proposed a multi-scale deep dehydration mechanism based on physicochemical coupling, and developed an underwater adaptive enhanced adhesive based on this mechanism, which realized strong underwater bonding in harsh environments (high/low pH, seawater), and obtained application verification in underwater sand fixation, underwater repair and adhesion failure detection. The results of the study were published in PNAS.

The multi-scale dehydration mechanism of physicochemical coupling includes the physical substitution of interfacial water at the millimeter scale with excellent wettability. Through the chemical reaction of isocyanate fragments and water in the adhesive to form a gas film, the physical shielding of interface water at the micron scale and the consumption of interfacial bound water at the molecular scale are realized. Underwater adaptively reinforced adhesives are a series of instantaneous and spontaneous contact, spreading, wetting and gelling processes that provide a strong bond to the substrate surface.

The underwater adaptive reinforced adhesive exhibits excellent underwater adhesion performance and a wide range of substrate applicability, and achieves high-performance adhesion from inorganic to organic material surfaces in freshwater, seawater and water with a peak value of more than 1600kPa. Good adhesion performance and adaptive enhancement characteristics without external energy input make underwater adaptive reinforcement adhesives show great application potential in underwater sand fixation, underwater repair and even adhesion fault detection.

Aiming at the study of the influence mechanism of interface water on underwater adhesion during solid-solid adhesion, the researchers proposed a multi-scale dewatering mechanism with physicochemical coupling, which realized the deep removal of adhesion interface water, shielded the influence of water on interface adhesion, and obtained underwater high-strength adhesion with adaptive gelation of adhesive. The multi-scale deep dehydration mechanism coupled with physics and chemistry has certain guiding significance for the design of underwater adhesion materials. (Source: Ye Manshan, China Science News)

Related paper information:https://doi.org/10.1073/pnas.2301364120

Schematic diagram of underwater adhesive dehydration process and adaptive adhesion. Photo courtesy of Lanzhou Chemical Institute.



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