New nanoindentation methodology for measuring local elastic modulus of nanostructured polymer systems

S. Watcharotone, X. Cheng, Y. Li, L.C. Brinson
NANOTEC, National Science and Technology Development Agency, TH

Keywords: nanoindentation, film, polymer, interface

Summary:

Nanostructured polymers play an important role in functional composite materials and thin films in various applications from electronics to medicine. A method to directly measure local mechanical properties of nanostructured polymer systems will be presented. A nanoindentation technique was implemented to investigate confined polymer systems and deconvolute the effects of substrates and chemical interactions at interfaces. Poly(methyl methacrylate), polystyrene and poly(2-vinyl pyridine) films coated on silica and alumina substrates were measured by nanoindentation. Results show that non-covalent chemical interactions are critical to the local changes of modulus. The chemical interactions at interfaces were determined indirectly by the work of spreading and surface energies based on the acid-base approach. This work sheds light on the roles of confinement and chemistry on mechanical properties.