State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P.R. China.
Angew Chem Int Ed Engl. 2016 Sep 12;55(38):11421-5. doi: 10.1002/anie.201602847. Epub 2016 Jun 8.
Thermoset polymers are known for their superior thermomechanical properties, but the chemical crosslinking typically leads to intractability. This is reflected in the great differences between thermoset and thermoplastic shape-memory polymers; the former exhibit a robust shape memory but are not capable of redefining the permanent shape. Contrary to current knowledge, we reveal here that a classical thermoset shape-memory polyurethane is readily capable of permanent reshaping (plasticity) after a topological network rearrangement that is induced by transcarbamoylation. By employing the Jianzhi technique (also known as kirigami), unexpected shape-shifting versatility was observed for this otherwise classical material. As the essential carbamate moiety in polyurethanes is one of the most common polymer building units, we anticipate that our finding will have significant benefits beyond shape shifting.
热固性聚合物以其优越的热机械性能而闻名，但化学交联通常会导致其不溶。这反映在热固性和热塑性形状记忆聚合物之间的巨大差异上；前者表现出稳健的形状记忆，但不能重新定义永久形状。与当前的认识相反，我们在这里揭示了一种经典的热固性形状记忆聚氨酯在通过转氨甲酰化诱导的拓扑网络重排后，很容易具有永久的可重塑性（塑性）。通过采用 Jianzhi 技术（也称为剪纸），观察到这种经典材料具有意想不到的多变形状能力。由于聚氨酯中的氨基甲酸酯部分是最常见的聚合物结构单元之一，我们预计我们的发现将超越形状变化带来重大益处。
