Nanoscale DMA with the Atomic Force Microscope: A New Method for Measuring Viscoelastic Properties of Nanostructured Polymer Materials

We introduce nanoscale dynamic mechanical analysis (DMA) based on atomic force microscopy (AFM), a new mode for quantitative viscoelastic analysis of heterogeneous polymer materials at the nanoscale (AFM-nDMA). AFM-nDMA takes advantage of the exquisite force sensitivity, small contact radius, and nanoscale indentation depth of the AFM to provide dynamic mechanical analysis with 10 nm spatial resolution at rheologically relevant frequencies and variable temperature. This novel, non-resonant measurement is embedded in a force curve and typically occurs at a series of frequencies to provide spectra of storage modulus, loss modulus, and loss tangent. By using tailored probes and mitigating the effect of contact radius changes throughout the measurement, quantitative results are obtained that tie directly to bulk DMA and allow for time-temperature superposition analysis. The combination of quantitative results and 10 nm spatial resolution holds promise for the investigation of previously inaccessible microscopic domains, confinement effects, and interphases.