Thermal transitions of polymers measured by atomic force microscopy

A new method has been developed to measure thermal transitions by atomic force microscopy in the non-contact mode, using it as a dynamic mechanical analyser on a local scale. In this method the cantilever is oscillating above the polymer surface and the resonance frequency is measured as a function of the temperature. Thermal transitions of a polymer are clearly visible as a change in the characteristic-frequency behaviour of the cantilever. This paper introduces a simple model to explain the response of the cantilever caused by the transitions in the polymer and the related form of the frequency/temperature curves. This new technique adds a new dimension to the standard thermal analysis techniques, with which the thermal transitions of different polymer phases can be resolved individually for polymer blends or copolymers, for example in structured multiphase polymers.