Scanning Probe Microscopy: Polymer Characterisation at the Microscale

摘要

Scanning Probe Microscopy (SPM) initially provided three-dimensional visualisation of surfaces down to atomic scale using Scanning Tunnelling (STM) and Atomic Force Microscopy (AFM). Today, a raft of imaging modes and spectroscopic techniques can be used to determine additional information on physical, chemical and thermal properties of polymeric materials. Examples of uses of lateral force microscopy to determine surface friction and force modulation to elucidate surface stiffness will be presented. Pulsed Force Mode now enables both these properties to be displayed simultaneously. Intermittent contact AFM (tapping) combine with phase imaging provides fast imaging of soft polymers combined with simultaneous materials contrast based on surface visco-elastic properties. Hence, the spatial distribution of multi-component polymers is determined. Typical examples include identification of filler/binder materials and calculation of percentage distribution of copolymers. Micro-Thermal Analysis uses a heated probe for thermal conductivity imaging. The same probe performs local calorimetric measurements through Micro Thermal Mechanical Analysis (TMA) and Micro-Differential Thermal Analysis (DTA). Application examples include co-polymer identification in food packaging materials, effects of embedded carbon fibres on matrix cross-linking and transparency films. Alternatively, a sample heating stage can be used to track temperature dependent morphology, stiffness and adhesion changes using Pulsed Force Mode.