Strong shape-memory adhesive could put Spider-Man to shame

You can stop skulking around labs trying to get bitten by radioactive spiders – a new breakthrough could make it easier than ever to get Spider-Man’s wall-crawling powers. Scientists in Singapore have created a strong and reusable adhesive out of a shape-memory polymer, sticking to and detaching from surfaces by changing the temperature.

The polymer is called E44 epoxy, and at room temperature it’s a stiff and glassy plastic, but once heated up it becomes soft and rubbery. In that state, it can ooze into the tiny crannies and crevices of another surface, allowing it to form extra-strong bonds if it’s then cooled down. If you later want to remove it, all you need to do is heat it back up.

In tests conducted by scientists at Nanyang Technological University (NTU) Singapore, the adhesive was able to grab onto a range of different textures and didn’t leave any sticky residue behind. Through experimentation, the team found that the best shape for the material was a series of hair-like structures called fibrils, each a few millimeters wide.

For example, one setup used fibrils with a cross section of 19.6 mm2 (0.03 in2), with each being able to hold up to 1.56 kg (3.4 lb). Adding more fibrils increases the maximum weight the material can hold, with a palm-sized pad of 37 fibrils holding a 60-kg (132-lb) weight.

“The technology will be very useful in adhesive grippers and climbing robots and might one day let humans climb walls like a real-life Spider-Man,” said Professor Jimmy Hsia, lead author of the study.

Don’t bother getting your spandex suit ready just yet, though – this shape-memory adhesive isn’t quite ready for prime time. For starters, it needs to be heated to 60 °C (140 °F) to detach from a surface, which takes up to a minute to reach using a hair dryer. Once pressed against a surface, it then takes about three minutes to cool down enough to lock into place. That’s not a practical temperature or speed for many uses, although it might work for industrial uses like robotic grippers carrying heavy loads, if they aren’t in a hurry. But the team says that with more work, it should be possible to change those triggers.

“Our findings show that reducing the wait times to mere seconds is possible, and the switching temperatures can be lowered to near body temperature, dramatically opening up application possibilities,” said Dr. Linghu Changhong, first author of the study. “The stimuli to switch the material from one state to another can also be different, such as using electrical current or light instead.”

Eventually, the team says that this technique could be used to make robots that can climb surfaces, or for climbing gear like gloves and boots for humans to wear.

The research was published in the journal National Science Review. Check out the adhesive in action in the video below.

NTU Singapore scientists develop a smart, reusable adhesive that sticks on various surfaces

Source: NTU Singapore

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