Quantitative investigation on the Young's modulus of ultrathin amorphous PS films attached to different substrates

Abstract

AbstractIn this work, a method combining nanomechanical characterization and finite element analysis (FEA) was applied to reveal the influence mechanism and quantify the effects of the substrate on the mechanical properties of the ultrathin polystyrene (PS) film. SiOx, polylactic acid (PLA), and polydimethylsiloxane (PDMS), respectively, were chosen as the substrate. Results show that PS film exhibits a Young's modulus that is completely different from that of the bulk when the thickness is lower than the end‐to‐end distance of PS, and the value is directly related to the substrate to which the film is attached. The equivalent Young's moduli of the 20 nm PS films attached to SiOx, PLA, and PDMS substrates are 4.9, 3.4, and 1.0 GPa, respectively, which is positively correlated with the Young's modulus of the substrates. It suggests that the substrate has non‐negligible and important influences on the mechanical properties of supported polymer ultrathin films. The results provide new insight into the unique physical properties of polymer ultrathin films and favor the design of polymer‐based nanodevices.