Reversing fatigue in carbon-fiber reinforced vitrimer composites

To address the irreversibility of fatigue in polymer composites, a recent study showed that vitrimeric polymers can be used to reverse the fatigue damage through topological rearrangement of the marcomolecular network, self-healing the polymers.

To study the initial crosslinking of these polymers and the transesterification exchange reactions that result in topological rearrangement of the molecular network, it takes around an hour to heal the vitrimer, which prohibits real-time simulation with conventional reactive molecular dynamics. To overcome this challenge, the researchers in Vashisth Lab used the bond boost accelerated ReaxFF feature (see tutorial). This method allows simulating the exchange reaction at realistic, low temperatures, which helps to mimic chemical reactions seen in experiments and avoids unwanted high-temperature side reactions and still allows the rejection of high-barrier events. The initial polymer structure and the healed polymer structure were characterized for modulus and glass transition temperatures, and showed good comparison with experiments.

Top: vitrimer under 0, 15 and 40% strain, showing breaking of the crosslinking network
Bottom: cross-linking (left) and healing transesterification (right) active atoms in bond boost acceleration
The real and simulated vitrimer shown by Aniruddh Vashisth

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M. Kamble, A. Vashisth, H. Yang, S. Pranompont, C. R.Picu, D. Wang, N. Koratkara, Reversing fatigue in carbon-fiber reinforced vitrimer composites, Carbon 187, 108 (2022)

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