Generally speaking, adhesives do not stick to wet surfaces very well. The moisture on the material prevents the adhesive to take hold. Researchers have been able to develop an adhesive that can quickly and securely stick to wet surfaces. The adhesive was made from a polymer that includes polyacrylic acid; this is a highly absorbent material that is used in diapers to soak up liquids. Once the liquid is removed, the adhesive can then bond with the wet surface. The bond however, was a weak one; therefore, the engineers in an effort to stabilize and strengthen the bond, added NHS esters.
It worked. The resulting adhesive tape provided a super-strong bond with wet surfaces. The potential applications of an adhesive tape like this are many, including ones in the medical field. The tape can be used to seam rips and tears in the body, such as in the lungs or intestines, or to attach implants and medical devices to organs, like the heart.
However, the bond that was created with this adhesive was too strong. It could not be removed without damaging the tissue to which it was attached. The engineers went back to the drawing board to make the adhesive detachable.
The engineers found that adding a disulfide linker molecule between the bonds made it possible to detach the adhesive when a certain reducing agent is introduced. When the reducing agent, made of glutathione and sodium bicarbonate, is sprayed onto the tape, the tape was able to be easily peeled away without any harm to the tissue below, no matter how long the tape had been on. The researchers went a step further introducing channels into the tape so that the reducing agent can be sent through, in cases where spraying is not an option; for example, when the tape was used to attach implants or devices.
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