Molecular dynamics modelling of polyrotaxane glass: From model construction to structure–property evaluation

Polyrotaxane glass (PRG) is a supramolecular polymer material in which cyclic molecules are threaded onto polymer chains, giving rise to exceptional ductility and toughness. However, the molecular origins of its mechanical behaviour and the influence of key structural design factors remain insufficiently understood, largely due to experimental challenges in observing nanoscale structural evolution during deformation. In this study, a systematic molecular dynamics (MD) modelling framework is developed to investigate the structure–property relationships of propionylated α-cyclodextrin–based PRG. The framework integrates controlled molecular construction, an automated density-based annealing protocol, and a geometry-based visualization strategy to analyse structural evolution during tensile deformation. Tensile simulations are performed with controlled variations in axis-polymer chain length, cyclodextrin (CD) modification degree, and CD coverage. The simulated stress–strain responses are compared with quasi-static experimental results to discuss qualitative consistency in the characteristic deformation sequence of PRG, while the influence of strain rate is also examined. Parametric simulations reveal that increasing chain length enhances deformation continuity and energy absorption, enabling the emergence of strain-hardening behaviour; higher CD modification degrees reduce yield and post-peak stresses by increased steric bulk and decreased packing density; and CD coverage exhibits only a modest effect under high-rate loading, with slight reductions in stress arising from steric congestion introduced by densely threaded rings. Overall, this work presents a systematic modelling framework and provides molecular-level insight into how structural parameters influence the mechanical response of PRG. These findings offer practical guidance for the rational design of next-generation polyrotaxane-based materials with tailored mechanical properties. • A comprehensive atomistic modelling workflow for polyrotaxane glass is developed. • Reliable amorphous multi-chain configurations are enabled by automated annealing. • Strain-rate-dependent behaviour is benchmarked against quasi-static experiments. • Deformation continuity and strain-hardening behaviour are governed by chain length. • Steric effects are introduced by changes in cyclodextrin modification and coverage.