Engineers from Massachusetts Institute of Technology have developed a hydrogel SuperGlue that boast toughness comparable to bonds between animals cartilages, tendons and bones, yet is made up of 90 percent water.

Nature has its own way of promoting unprecedented adhesive powers that animals are benefiting from. For example, mussels are able to stick to whale skin, cliff edges and ship hulls. Aside from that, some animals are able to enjoy having access to efficient adhesive features, such as those found on their skeletal structures.

The natural sticky power comes from what is called hydrogel, which is a combination of water and gummy substance that forms a durable and sturdy bond.

In their experiment, MIT researchers showcased the resilience of hydrogel by applying a small dollop between two glass plates and hung a 55-pound weight from it. In another investigation, the scientists applied hydrogel to a silicon wafer and pounded it with a hammer. The result? The wafer fragmented yet the pieces remained in place due to the stick hydrogel.

To create the hydrogel, the researchers led by Hyunwoo Yuk, a mechanical engineering graduate student at MIT, mixed water with a dissipative agent to form a stretchy solution. He then applied it on top of different surfaces including glass, titanium and aluminum, which were all altered with functional silanes - an inorganic compound that formed chemical chains between the surfaces and the hydrogel.

"It's a pretty tough and adhesive gel that's mostly water," said Yuk. "Basically, it's tough, bonding water."

Hydrogel that is both durable and flexible yet still has powerful bonding powers necessitates two properties: energy dissipation and chemical anchorage. Hydrogel that disperse energy is vital in exhibiting stretchy characteristics without preserving all the energy utilized to stretch it. Chemical anchorage comes in handy as it enables hydrogel to stick to a surface by covalently bonding its polymer system to that surface.

The durability of hydrogel may be beneficial in numerous applications, particularly in protective underwater coatings for water vehicles like boats and submarines. Because natural hydrogel is biocompatible, it may also enhance the manufacturing of medical equipment that needs biomedical coverings such as catheters and sensor implants.

"You can imagine new applications with this very robust, adhesive, yet soft material," said Xuanhe Zhao, associate professor in the Department of Mechanical Engineering at the MIT. Zhao and colleagues are currently working on an experiment that explores the use of hydrogel in soft robotics, specifically in making synthetic joints, tendons and cartilages.

The study was published in the journal Nature materials on Monday, Nov. 9.

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