Bao Xianyang, Chen Zheqi, Nian Guodong, Tan Matthew Wei Ming, Ahn Christine Heera, Kutsovsky Yakov, Suo Zhigang
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China.
Nat Commun. 2025 May 22;16(1):4749. doi: 10.1038/s41467-025-59875-z.
Polymers crosslinked by covalent bonds suffer from a conflict: dense covalent crosslinks increase modulus but decrease fatigue threshold. Polymers crosslinked by physical bonds commonly have large hysteresis. Here we simultaneously achieve high modulus, high fatigue threshold, and low hysteresis in a network of unusually long polymer chains crosslinked by domains of physical bonds. When the network without precrack is pulled by a moderate stress, chains in the domains slip negligibly, so that the domains function like hard particles, leading to high modulus and low hysteresis. When the network with a precrack is stretched, the chains in the domains at the crack tip slip but do not pull out. This enables high tension to transmit over long segments of chains, leading to a high fatigue threshold.
密集的共价交联会提高模量，但会降低疲劳阈值。通过物理键交联的聚合物通常具有较大的滞后现象。在此，我们在由物理键域交联的异常长的聚合物链网络中同时实现了高模量、高疲劳阈值和低滞后现象。当无预裂纹的网络受到适度应力拉伸时，域中的链几乎不发生滑移，因此这些域起到了硬颗粒的作用，从而实现了高模量和低滞后现象。当带有预裂纹的网络被拉伸时，裂纹尖端域中的链会发生滑移但不会被拔出。这使得高张力能够在长链段上传递，从而实现了高疲劳阈值。
