Zhenwei Jiang, Weihang Tian, Wenwu Weng, Xiaozhi Zhan, Xianjing Zhou, Jianquan Xu, Tao Zhu, Xinping Wang
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引用次数: 0
Abstract
The free surface effect in nanoconfined polymer systems is important. Hence, understanding the influence of polymer structures on the free surface effect is essential. Herein, the dynamics of the free surface of polystyrene, poly(4-methylstyrene), and poly(4-tert-butylstyrene) with p-substituted methyl and tert-butyl groups in the benzene ring were investigated. An enhanced free surface effect was exhibited by polymers with large side groups and high fragility, which was attributed to the high free volume of the surface and the long distance for this unusual free volume to propagate into the bulk. This phenomenon was proven by deuterium oxide vapor penetration into the film surface via neutron reflectivity. High levels of packing frustration could be relieved on the free surface of fragile polymers during film formation; the chain packing efficiency on the surface was reduced, resulting in a large and broad free volume distribution on the free surface. This study provides a deep understanding of the relationship between the free surface effect and the chemical and physical properties of polymers.
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.
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