The molecular dynamics of condensed polymers are directly linked to practically important mechanical properties, such as glass transition behavior and impact strength. We present a unique viscoelastic glass-forming polyrotaxane that is comprised of a main chain polymer and threaded cyclodextrins. The abnormally broad glass transition phase is attributed to the segment motion, which is unprecedentedly insusceptible to cooperative motion with neighboring chains until vitrification is completed. Even in the glass state, in which the cyclic components, occupying >80 wt % of the material, are vitrified, the main chain polymer retains high mobility within the glassy porous framework. The anomalous mobility of the polymer chains causes strong subrelaxation that changed the elastic modulus about 3-fold. These results demonstrate that the unique dynamics and mechanics are attributable to the loose correlation between different components, suggesting the possible creation of unprecedented mechanical properties based on the molecular design of mechanically interlocked polymers.
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