Unraveling the ultrahigh modulus of resilience of Core-Shell SU-8 nanocomposite nanopillars fabricated by vapor-phase infiltration

•AlOx/SU-8 nanocomposite nanopillars with core–shell structure were synthesized by Vapor-Phase Infiltration method.•Core shell regions possess unique interconnecting-particulate microstructures that cannot be obtained by a conventional solution-based method.•Polymer-like Young’s modulus and metal-like high yield strength lead to a modulus of resilience close to its theoretical upper limit.•Negligible strain-rate dependence of modulus of resilience attributes to the viscoelasticity of SU-8 with the low degree of cross-linking.•Our work provides an optimized composite microstructural design that can absorb a large amount of elastic energy.