Polymer single chain imaging, molecular forces, and nanoscale processes by Atomic Force Microscopy: The ultimate proof of the macromolecular hypothesis

Polymers have dominated materials technology over the last century and remain a major field despite emerging environmental and petroleum-supply-related problems. However, for a long time, covalent macromolecules were considered “fictive constituents of matter”. Scientific evidence supporting Staudinger's hypothesis remained indirect as, for a long time, no real space observation of molecules and phenomena related to single molecules had been possible. This was changed by the widespread introduction and use of scanning probe techniques, in particular, Atomic Force Microscopy (AFM). In macromolecular nanoscience and nanotechnology and in polymer analysis and characterization, AFM and related techniques have become an enabling technology platform. We review major recent developments on the basis of a historical account and summarize some breakthrough results with a focus on single molecule imaging, molecular force measurements, and processes monitored at the molecular scale.