Manipulation of a Single Polymer Chain: From the Nanomechanical Properties to Dynamic Structure Evolution

Exploring the relationship between the polymer structure and property/function is a long-lasting topic in polymer science since relevant research is critical for the rational design of polymer materials or the control of biological functions. Due to the complexity of the real material and biological systems, it is quite difficult to establish such a relationship using traditional ensemble measurements. Single-molecule force spectroscopy (SMFS), which can be used to manipulate individual polymer chains, is a powerful technology for investigating the inter- or intramolecular interactions, chain structures and their dynamic behaviors with piconewton force and subnanometer spatial precision at the single-molecule level. In this Perspective, focusing on atomic force microscopy (AFM)-based SMFS, we first highlight recent advances in the AFM-SMFS study of mechanical properties in polymer systems, including the structure–mechanics relationships in polymer single crystal, covalent mechanochemistry of polymer, and polymer–nanoparticle composites. Then we highlight the recent advancement in the exploration of higher-order structures and their dynamic conversion in DNA using SMFS. We emphasize the prominent role of the application expansion of SMFS, innovation of experimental methods and sample preparation. At the end, future challenges and opportunities on single-molecule manipulations of polymers are discussed. We hope that this Perspective will also attract further attention from the material, biological, and computational research community, which would speed up our understanding on the structure–property (function) relationship of polymers.