Mechanically robust, readily repairable polymers via tailored noncovalent cross-linking:Academic support specialist Yu Yanagisawa, Mr. Yiling Nan, Assistant Professor Kou Okuro, Professor Takuzo Aida,



Yu Yanagisawa, Yiling Nan, kou Okuro, and Takuzo Aida




Expanding the range of healable materials is an important challenge for sustainable societies. Noncrystalline, high molecular weight polymers generally form mechanically robust materials, which, however, are difficult to repair once they are fractured. This is because their polymer chains are heavily entangled and diffuse too sluggishly to unite fractured surfaces within reasonable timescales. Here, we report that low molecular weight polymers, when cross-linked by dense hydrogen bonds, give mechanically robust yet readily repairable materials, despite their extremely slow diffusion dynamics. A key was to utilize thiourea, which anomalously forms a zigzag hydrogen-bonded array that does not induce unfavorable crystallization. Another key was to incorporate a structural element for activating the exchange of hydrogen-bonded pairs, which enables the fractured portions to rejoin readily upon compression.