Standardization of nanoscale interfacial experiments using MEMS

A novel experimental method for the interfacial mechanics of nanofibers and nanotubes was developed. The debond force was determined by MEMS devices whose motion was precisely measured from optical images by digital image correlation. Essential elements of this method are the submicron control of nanofiber/nanotube embedded length in a thermoplastic or thermosetting polymer and the application of well controlled pull-out force until terminal debonding. The cross-head displacement resolution is at least 20 nm and the force resolution of the order of nanonewtons. A traceable force calibration technique was integrated to calibrate the MEMS force sensors. The method allows for nanofiber pull-out experiments at time scales varying from microseconds to hours and at hot/cold temperatures. Experiments have been conducted for the first time with ∅150-350 nm carbon nanofibers embedded in EPON epoxy to quantify the role of nanofiber surface functionalization in the interfacial shear strength. It was clearly shown than surface functionalization drastically increases interfacial adhesion by a factor of three. The present experiments are the first of their kind both in terms of experimental fidelity and data coherence compared to prior experimental attempts, pointing out the robustness of this new experimental method.