https://orcid.org/0000-0002-5413-8246
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ABSTRACT
Typically, polyurea is a polymer forming microphase-separated structures. Various coarse-grained (CG) simulation models have been developed to study the microphase structure and viscoelastic properties of polyurea. However, since the hydrogen atoms were modelled implicitly in the existing CG models, the anisotropic hydrogen bonding between urea groups in the hard domain might not be treated properly. Here, we introduce a hybrid all-atom/coarse-grained (AA/CG) model for polyurea, the CGU model, in which atomistic resolution are preserved for the urea groups. This model is proven to reproduce the results of the AA model, despite 24 times faster to run. By comparing the traditional CG model and the CGU model, we found that hydrogen bonding leads to a head-to-tail arrangement of the urea groups and a significant slowdown of the hard segment dynamics. Non-equilibrium simulations of stress relaxation process indicate that hydrogen bonding causes a broad relaxation time spectrum, which is consistent with experiment results.
5. Supplementary material
The supplementary material contains details of the AA MD simulations of polyurea, the IBI method, model validation figures and model parameters.
Acknowledgements
The authors are deeply grateful to Tsinghua University Scientific Research Project (grant number 20194180048) and the financial support from National Natural Science Foundation of China (grant number U1862205, 51473085 and 51673110).
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data available
The data that support the findings of this study are available from the corresponding author upon reasonable request. The parameters of the CG and CGU models can be found in the supplementary material.