Direct Observation of the “End-Capping Effect” of a PEG@α-CD Polypseudorotaxane in Aqueous Media

IF 5.1 1区化学 Q1 POLYMER SCIENCE

Macromolecules Pub Date : 2025-03-04 DOI:10.1021/acs.macromol.4c02491

Ryoga Hori, Ken-ichi Shinohara

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Abstract

This study demonstrates that the shuttling of α-cyclodextrin (α-CD) rings in a poly(ethylene glycol) (PEG) polypseudorotaxane drives the shrinkage and extension of the molecule and that a strong end-capping effect stabilizes the structure at the solid–liquid interface. We performed single-molecule imaging of PEG_100k@α-CD polypseudorotaxane under aqueous solution using fast-scanning atomic force microscopy. The polypseudorotaxane displayed shrinking and extending motions driven by the α-CD rings shuttling along the polymer chain. These motions mainly occurred in exposed, self-shrinking PEG segments, where repeated expansion and reshrinking were observed as α-CD moved. All-atom molecular dynamics simulations corroborated these findings, confirming dynamic structural changes linked to α-CD shuttling. Additionally, globules formed at both ends of the PEG chain caused a strong end-capping effect that stabilized the structure in solution. These insights into the localized structural changes in PEG@α-CD polypseudorotaxane improve our understanding of supramolecular functionality and could inform the design of advanced materials.

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来源期刊

Macromolecules 工程技术-高分子科学

CiteScore

9.30

自引率

16.40%

发文量

942

审稿时长

2 months

期刊介绍： Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.