Water-mediated hydrogen bonds and local side-chain interactions in the cooperative collapse and expansion of PNIPAM oligomers

• 成果类型: Article
• 署名作者: Chen, Wanlin; Gruebele, Martin; Havenith, Martina; Hebel, Kurt J.; Scaletti, Carla
• 署名单位: Ruhr University Bochum; University of Illinois System; University of Illinois Urbana-Champaign; University of Illinois System; University of Illinois Urbana-Champaign; University of Illinois System; University of Illinois Urbana-Champaign; Universite Paris Cite; Centre National de la Recherche Scientifique (CNRS)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2523755123
• 发表日期: 2026-02-10
• 页码: e2523755123
• 关键词: sonification; bound water; wrap water; polymer compactification; water-mediated interactions; molecular-dynamics; SOLUTION BEHAVIOR; POLY(N-ISOPROPYLACRYLAMIDE); TRANSITION; simulation

摘要

Poly(N-isopropylacrylamide) (PNIPAM), a thermoresponsive homopolymer, is a well-established model for investigating coil-to-globule transitions. Here, we combine to elucidate the roles of intramolecular and PNIPAM-solvent hydrogen-bond (H-bond) patterns in the PNIPAM globule-coil equilibrium. Our analysis separates the driving forces for compaction into two contributions: the entropic gain from the loss of hydration water around hydrophobic patches and the enthalpic stabilization from water H-bonded to PNIPAM. We find that the role of the solvent in polymer compaction is more active and complex than has been previously assumed. Our observations indicate that direct, intrachain hydrogen bonds between amide groups (N-H & centerdot;& centerdot;& centerdot;O=C) are not the primary stabilizing force. Instead, the collapsed globule contains an N-H & centerdot;& centerdot;& centerdot;N network of local side-chain interactions and is stabilized by a dynamic network of persistent, with multiple parts of the polymer chain.