Reactive molecular dynamics simulations of the intra- and intermolecular reactions of hydrogen-abstracted polyethylene chains

HL Li and S Fujiwara and H Nakamura and T Mizuguchi and S Saito and W Sakai, MOLECULAR SIMULATION, 51, 122-127 (2025).

DOI: 10.1080/08927022.2025.2465809

Polymers can be radicalised by radiation, and the reaction of the generated radicals with each other could result in structural changes in the original material. Our previous reactive molecular dynamics (MD) simulations showed that several types of reactions occur at specific locations in polymer structures at low temperatures. However, not much is known about the occurrence of other types of reactions for these materials. In this study, reactive MD simulations were performed on hydrogen-abstracted polyethylene chains to clarify the conditions under which other types of reactions, such as chain scission and crosslinking, occur. Our simulation results showed that chain scission occurred only at a specific location at temperatures of 348 K or higher. Intermolecular crosslinking occurred only when two CH radicals were fixed at a distance of approximately 2.0 & Aring; apart. However, our simulations also indicated that such movement does not occur freely owing to repulsive forces. These findings provide a new understanding of the structural changes and chemical reactions of polymers caused by radiation damage.

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