The intrinsic conflicts between mechanical performances and processability are main challenges to develop cost-effective impact-resistant materials from polymers as well as their composites. Herein, sub-nanoscale molecular units, polyhedral oligomeric silsesquioxanes (POSSs) are covalently integrated as side chains to polymers with rigid backbones. The 1D rigid topology imposes strong space confinements to realize synergistic physical interactions among POSS units, reinforcing the correlations among polymer chains. The afforded entanglement-free polymers, though possess low molecular weights, demonstrate unprecedented mechanical properties with ultra-stretchability, strengths with extremely high strain rate-dependence, superior impact-resistant capacities as well as feasible processability/recoverability. The hierarchical structures of the hybrid polymers enable the co-existence of multiple dynamic relaxation processes that are responsible for fast energy dissipation and high mechanical strengths. The effective synergistic correlations strategy is entirely distinct from that of covalent and supramolecular systems, which paves a new pathway for the design of advanced cluster-based materials.