Variations of Rheological Properties and Wall Slip of Polyethylene in Nanoconfined Channels Studied by MD Simulation

IF 5.1 1区化学 Q1 POLYMER SCIENCE Macromolecules Pub Date : 2024-11-30 DOI:10.1021/acs.macromol.4c01775

Nana Qiu, Yinxiang Xu, Duo Wang, Huijuan Bai, Junbo Xu, Chao Yang

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Abstract

In this work, the all-atom molecular dynamics (MD) simulation is employed to study the flow characteristics of polyethylene (PE) melts in a nanoconfined system. Except for the wall slip, the deviations of the non-Newtonian index of PE melts in the nanochannel from the bulk fluid were found. The simulation results demonstrated that the slip velocity (v_s) follows the power law v_s = aτ^b_w, and its correlation with the wall–fluid interaction was analyzed. More importantly, the anisotropic conformation of PE molecules and its discrepancy with the nonconfined system was manifested by the radius of gyration. The non-Newtonian index increased closer to 1 as the slit height decreased due to the elongation of polymer chains in the flow direction. The migration of polymer chains became smoother, and two fluid layers near the wall almost not exchanging with bulk region molecules were found. This work provides helpful insights for understanding nanoscale non-Newtonian fluid hydrodynamics behaviors.

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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.