Atomic force probe of mesoscopic dielectric and viscoelastic fluctuations near the glass transition

摘要

We report a new experimental approach to study the glass transition and glassy dynamics on a mesoscopic scale. Non contact atomic force microscopy is employed to measure dielectric fluctuations of glass forming polymers such as PVAc. Force modulation techniques, performed with the same instrument, allow us to study viscoelastic properties. A custom-built variable temperature UHV AFM with exceptional thermal stability utilizing piezoresistive cnatilevers was used. First results on PVAc include large fluctuations of the viscoelastic properties as a function of applied stress below the glass transition.