Observation of polymer chain structures in two-dimensional films by atomic force microscopy

Abstract

The visualization of polymer structures at the molecular level is one of the most important issues in polymer science; however, even using scanning probe microscopy techniques such as atomic force microscopy (AFM), it is still challenging to observe soft polymer materials at the molecular level. In this review, we show that using two-dimensional (2D) samples suitable for AFM observation, especially Langmuir-Blodgett films, and by optimizing the scan conditions, it is possible to obtain molecular images of various polymer structures by tapping-mode AFM. The molecular-level observations included isolated polymer chains and their movements on substrates, 2D folded-chain crystals and their melting behavior, crystallization behavior of single isolated chains, supramolecular multistranded stereocomplexes and chain packing in monolayers. The molecular-level information obtained by this type of direct observation is expected to greatly improve our understanding of physical properties of polymers.