在如今科技飞速发展的时代，功能材料和设备不断向小型化迈进，这就要求聚合物薄膜的厚度越来越接近分子长度尺度。当聚合物薄膜处于这种极度受限的环境中时，它的力学性能会与大块材料的表现截然不同。理解这种尺寸效应背后的微观原理，对于从分子层面设计聚合物材料至关重要。科学家们通过结合温控原子力显微镜的挠度测试、单分子力谱以及分子动力学模拟等方法，揭开了超薄聚合物薄膜机械硬化的微观基础。研究发现，随着薄膜厚度的减小，受限环境会改变聚合物链的变形方式。原本依靠分子间较弱的内聚力来传递载荷，逐渐转变为直接的链内拉伸来承受外力。通过对聚碳酸酯和聚甲基丙烯酸甲酯薄膜的对比研究，科学家们还确定了影响薄膜强化程度的关键因素是链的刚性，而不是链的排列方式或者缠结密度。基于这些发现，科学家们提出了“滑动 - 拉伸竞争机制”，这个机制能够解释不同实验技术得出的结果差异。这一研究成果为制造具有机械强度的聚合物纳米薄膜和分层结构提供了分子层面的设计规则，未来有望应用于下一代柔性电子设备和防护涂层等领域。

期刊

Macromolecules

标题

Chain-Rigidity-Governed Mechanical Stiffening of Polymer Ultrathin Films

作者

Zhao Zhang, Jiahao Li, Shuhui Yan, Yafei Wang, Xiqi Wu, Xinshuai Peng, XinAn Chen, YinBo Zhu, HengAn Wu, Guorui Wang, Zhong Zhang

摘要

Increasing the miniaturization of functional materials and devices demands polymer films with thicknesses approaching molecular length scales. Under such extreme confinement, polymer mechanics deviate sharply from bulk behavior. Of particular importance is understanding the microscopic origin of such size effects to build design principles at the molecular level. Here, we uncover the microscopic basis of mechanical stiffening in ultrathin polymer films by integrating temperature-controlled atomic force microscopy-based deflection testing, single-molecule force spectroscopy, and molecular dynamics simulations. We demonstrate that confinement alters chain-level deformation pathways, shifting load transfer from weak intermolecular cohesion to direct intrachain stretching as the thickness decreases. Comparative studies of polycarbonate and poly(methyl methacrylate) films further confirm that chain rigidity─rather than chain alignment or entanglement density─dominates the extent of reinforcement. We unify these findings in a sliding–stretching competition mechanism, which reconciles discrepancies across diverse experimental techniques. This framework establishes molecular-level design rules for creating mechanically robust polymer nanofilms and layered architectures with tailored performance for next-generation flexible electronics and protective coatings.

原文链接

https://pubs.acs.org/doi/10.1021/acs.macromol.5c02437

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静远嘲风-南京（MY Scimage） 成立于2007年，嘲风取自中国传统文化中龙生九子，子子不同的传说，嘲风为守护屋脊之瑞兽，喜登高望远；静远取自成语“宁静致远”，登高莫忘初心，远观而不可务远。

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