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."
“啪”！橡皮筋斷了。遇到這種情況，我們都知道該去換根新的。

不過，法國一組科研人員日前研制出一種可以“自我愈合”的橡皮筋材料，用這種材料制成的橡皮筋斷了之后，只需將斷裂兩端按住幾分鐘，就能恢復得完好如初。

這個新成果在本周三的《自然》期刊上公布。據介紹，這種材料能夠反復地斷裂修復。

這種新材料的成分很簡單——即蔬菜油及尿素（隨尿液排出的一種可合成的化合物）中所含的脂肪酸。

巴黎“工業物理與化學高等教育研究所”的菲利浦•科迪亞及其同事寫道，這種材料在工業領域大有用處，而且它甚至能為彈性物理學提供新的信息。

標準橡皮筋由交錯連接的長鏈聚合物制成，能拉伸至原先長度的幾倍，釋放后可縮回原型。

這種新材料則由一種名叫“ditopic” 的分子短鏈結構組成。

如果斷了，只需在室溫條件下將其斷裂兩端按住幾分鐘，即可自我修復。

科迪亞及其同事寫道：“修復后的皮筋能夠承受很大拉力，在外力釋放后即可恢復原型。”

東京大學的賈斯汀•麥納和Takuzo Aida在一篇文章中寫道，這種材料“能承受多次斷裂，不需要催化劑，而且易于制造。”

“還有一大優點是，這種材料經過加熱后能熔解，易于回收，所以，它又是一種環保材料。”