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Despite the efforts of people, but the strength of man-made fibers still can not match the strength of natural fibers.

Recently, US scientists used natural silk fibers as raw materials to successfully prepare new materials that are several times harder than natural silk fibers, with complex and diverse shapes and structures. They call this new material "recycled silk fiber (RSF)." The research was published in Nature Communications, a collaboration between researchers at MIT and Tufts University.

Natural silk fiber is a natural protein fiber secreted by insects such as silkworm, spider and so on. Spider silk is one of the hardest materials known. However, spiders have the same type of eating personality, can not be high-density farming, and silkworm can solve this problem, produce a lot of fiber. All along, many researchers have tried to prepare pure synthetic silk, but the product strength is not as good as natural silk fiber. As a result, the Buehler team has developed a new approach that takes advantage of the natural properties of natural silk itself and increases its strength, as well as the novel shapes and structures that natural silk can not form.

They use natural silk as the basic raw material, destroy them first, and then recombine to obtain regenerated silk fiber.

The key to this method is to partially destroy natural silk. They dissolve the cocoon, but do not break the molecular structure, but rather get an intermediate for microfibril formation. These small filamentous intermediates retain an important hierarchical structure, and it is these structures that give silk high strength.

Buehler, director of the Department of Civil and Environmental Engineering, compared the recycling of this natural material to the demolition of an old brick house, but instead of disassembling the house into a pile of rubble, he completely removed each brick, Then use them to build new structures. "It is the use of natural materials that makes the unique strength and stretch properties of regenerated silk fibers, and we harness the power of nature," he said.

The prepared regenerated silk fiber is 2 times harder than the traditional silk fiber and has a hardness close to that of spider dragging silk.

Researchers are able to make a wide variety of shapes that natural silk can not reproduce, such as webs, tubes, thicker fibers than natural silk, coils and sheets. These different shapes can be prepared using a 3D printing system suitable for silk solutions. The researchers said that the traditional preparation method can be used to prepare regenerated silk fiber, it is easy to achieve large-scale production, and by changing the extrusion speed can be adjusted fiber properties.

Although silk and silk are expensive, the cost of this regenerated silk fiber comes primarily from manpower because it is labor-intensive to remove the silk from cocoons and then re-weave them. In fact, the cost of acquiring silkworm and silkworm cocoon is relatively low. Unprocessed high-volume cocoon became only $ 5 / kg.

The study laid the groundwork for a new range of fabric materials and functional composites, with a wide range of applications in the future, such as a new generation of textiles and biosensors. For example, silk is a natural biocompatible material that does not cause any adverse reactions in the human body. Therefore, this new material is suitable for use as a biomaterial such as medical suture or scaffold.

In addition, the regenerated silk fiber is sensitive to humidity and can be made into a conductor by adding a negative electrode material coating such as carbon nanotube. This can be applied to a variety of sensitive components, such as changes in fingertip pressure or in the environment. For example, one possible application is the sheets that can be used as healthcare devices. By monitoring stress, caregivers are automatically alerted when the patient is lying in the same position for too long, helping to prevent bed sores. Such applications can be quickly implemented without any hurdles.