Reusable Underwater Adhesive Bonds in Ten Seconds

A newly developed adhesive can form a strong bond underwater within ten seconds. The experimental material could simplify repairs to submerged infrastructure, while its reversible molecular structure allows it to be removed and reused.

Researchers from Hunan University and other institutions developed the adhesive and presented their findings in Nature Communications. It adheres to various materials, including ceramics, epoxy and several plastics. After ten seconds underwater, the researchers measured an adhesive strength of up to approximately 1.1 megapascals.

The resulting bond also offers long-term water resistance. In one demonstration, an adhesive joint held a two-kilogram weight for more than three years while remaining continuously submerged.

Water Activates The Adhesive

Water usually prevents adhesives from forming strong bonds. Molecules accumulate on wet surfaces and create a microscopic hydration layer. Consequently, an adhesive must first penetrate this barrier before it can make direct contact with the underlying material.

The new adhesive turns this problem into part of the bonding process. It contains a supramolecular ionic liquid called BP16TPB, combined with dimethyl sulfoxide (DMSO). When the mixture contacts water, a solvent exchange begins. This process rearranges the molecules and creates a dense network through hydrogen bonds, electrostatic forces and π–π interactions.

Initially, the material flows easily across the surface. Underwater, however, it rapidly self-assembles into a strong, water-resistant layer.

Surface Tension Improves Bonding

The Marangoni effect also contributes to the adhesive’s performance. This physical phenomenon causes liquids to move in response to differences in surface tension. Within the adhesive, this movement helps distribute the material quickly across the target surface.

At the same time, the flow accelerates molecular assembly and helps the adhesive break through the hydration layer. Its water-repellent properties then push moisture away from the contact area. Unlike many conventional underwater adhesives, water therefore triggers the formation of the final bond instead of weakening it.

Reversible Connections For Underwater Repairs

The researchers detached and reapplied the adhesive underwater during testing. It continued to perform well after eight reuse cycles. This reversibility results from molecular interactions that can separate and subsequently reorganise, rather than relying entirely on permanent chemical bonds.

Tests also demonstrated adhesion in acidic, alkaline and saline environments. Potential applications include the repair of pipelines, offshore installations, ships and other structures that cannot easily be dried. However, performance decreases above approximately 70°C, and the technology remains at the experimental stage.

For architects, product designers and engineers, the research presents an interesting direction for fast, durable and potentially recyclable bonding in wet or submerged environments.

Source: TW
Photo: Michael M