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

Abstract

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.

Sacrificial Mechanical Bond is as Effective as a Sacrificial Covalent Bond in Increasing Cross-Linked Polymer Toughness

“…For example, our results suggest that the maximum tensile force a rotaxane can withstand without dethreading depends systematically on the steric bulk of the stoppers, potentially enabling the design of rich dynamic behavior resulting from kinetic competition between load relaxation by dethreading and the dissociation of covalent bonds. Such competition has been shown to allow detailed characterization of chain dynamics that is too complex for any alternative method and was previously speculated to enable detailed mechanistic studies and the design of new mechanoresponsive polymers. , Unlike chemical sacrificial bonds, whose capacity to affect bulk ,,,, and single-chain − mechanical properties of polymers has been extensively studied and exploited for several decades now by polymer scientists, biophysicists, and physical chemists, the potential of a mechanical sacrificial bond remains wholly unexplored.…”

Evolution of the Deformation‐ and Flow‐Induced Crystallization and Characterization of the Microstructure of a Single Spherulite, Lamella, and Chain of Isotactic Polypropylene

“…The conformation-dependent chain mobility will produce the force-fingerprint spectrum of the corresponding polymer system, which can be used to identify the chain folding directly. [161,165] Moreover, the AFM-based SMFS could adequately capture the Figure 16. FM-AFM Df error image of uniaxial stretching iPP: a-d) draw ratio 200%, e-h) draw ratio 1500%, i) and j) cross-sectional profile of h).…”

Single-Chain Inherent Elasticity of Macromolecules: From Concept to Applications

“…In the middle of the 20th century, Flory and other pioneers put forward several statistical mechanical models to semiquantitatively describe the single-chain elasticities of polymers in theory. , With the advent of single-molecule atomic force microscopy (AFM), the elastic behaviors of individual macromolecules have been extensively researched experimentally since the 1990s. − Although great progress has been made toward understanding the single-chain properties of macromolecules, many challenges still remain in this field. − With a backbone and side chains, a polymer chain is more complex than a small molecule. Moreover, a single polymer chain is usually placed in a complicated environment such as solvent, cosolute, and solid surface, which significantly affects the behaviors of the chain.…”