Snap! Scientists make a self-healing rubber band

Anyone who has heard the snap of a rubber band breaking knows it's time to reach for a replacement.

But a group of French scientists have made a self-healing rubber band material that can reclaim its stretchy usefulness by simply pressing the broken edges back together for a few minutes.

The material, described on Wednesday in the journal Nature, can be broken and repaired over and over again.

It is made from simple ingredients -- fatty acids like those found in vegetable oils, and urea, a waste compound in urine that can be made synthetically.

The material would be an asset to industry and might even help shed light on the physics of elasticity, wrote Philippe Cordier and colleagues at the Industrial Physics and Chemistry Higher Educational Institution in Paris.

Standard rubber bands, which can stretch up to several hundred percent then snap back into shape, are made from long chains of cross-linked polymers.

The new material is linked by short chains of a type of molecule called ditopic.

If severed, the material mends itself when the ends are pressed together for a few minutes at room temperature.

"The mended samples are able to sustain large deformations and recover their shape and size when stress is released," Cordier and his colleagues wrote.

The material can "withstand multiple fractures, needs no catalysts and is otherwise straightforward to produce," Justin Mynar and Takuzo Aida of the University of Tokyo wrote in an accompanying article.

"A final blessing is that it can be broken down with heat and easily recycled -- so it is environmentally friendly, too."

(Agencies)

“啪”！橡皮筋断了。遇到这种情况，我们都知道该去换根新的。

不过，法国一组科研人员日前研制出一种可以“自我愈合”的橡皮筋材料，用这种材料制成的橡皮筋断了之后，只需将断裂两端按住几分钟，就能恢复得完好如初。

这个新成果在本周三的《自然》期刊上公布。据介绍，这种材料能够反复地断裂修复。

这种新材料的成分很简单——即蔬菜油及尿素（随尿液排出的一种可合成的化合物）中所含的脂肪酸。

巴黎“工业物理与化学高等教育研究所”的菲利浦•科迪亚及其同事写道，这种材料在工业领域大有用处，而且它甚至能为弹性物理学提供新的信息。

标准橡皮筋由交错连接的长链聚合物制成，能拉伸至原先长度的几倍，释放后可缩回原型。

这种新材料则由一种名叫“ditopic” 的分子短链结构组成。

如果断了，只需在室温条件下将其断裂两端按住几分钟，即可自我修复。

科迪亚及其同事写道：“修复后的皮筋能够承受很大拉力，在外力释放后即可恢复原型。”

东京大学的贾斯汀•麦纳和Takuzo Aida在一篇文章中写道，这种材料“能承受多次断裂，不需要催化剂，而且易于制造。”

“还有一大优点是，这种材料经过加热后能熔解，易于回收，所以，它又是一种环保材料。”

Vocabulary:

shed light on:阐明,把...弄清楚

(news from Chinadaily)