Quantitative nanoscale mechanical properties of a phase segregated homopolymer surface

Crystallization of poly(ethylene terephthalate) (PET) is accompanied by sig nificant changes in surface topography, easily detected by atomic force mic roscopy (AFM), Phase imaging by AFM qualitatively indicates contrast in mec hanical properties of nanometer scale areas of an annealed PET surface, but cannot provide quantitative data. Using interfacial force microscopy (IFM) , we have, for the first time, made quantitative measurements of the elasti c moduli of such nm-scale areas on a homopolymer surface. Values of 2.2 GPa , 4.3 GPa, and 11.8 GPa, were found, respectively, for amorphous PET and fo r phase segregated regions on the surface of an annealed homopolymer PET sa mple. The method is applicable to any phase segregated surface with nm-size d domains of differing elastic moduli.