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Morphologies of a spherical bimodal polyelectrolyte brush induced by polydispersity and solvent selectivity 下载免费PDF全文
Qing-Hai Hao 《中国物理 B》2021,30(6):68201-068201
It is commonly realized that polydispersity may significantly affect the surface modification properties of polymer brush systems. In light of this, we systematically study morphologies of bidisperse polyelectrolyte brush grafted onto a spherical nanocolloid in the presence of trivalent counterions using molecular dynamics simulations. Via varying polydispersity, grafting density, and solvent selectivity, the effects of electrostatic correlation and excluded volume are focused, and rich phase behaviors of binary mixed polyelectrolyte brush are predicted, including a variety of pinned-patch morphologies at low grafting density and micelle-like structures at high grafting density. To pinpoint the mechanism of surface structure formation, the shape factor of two species of polyelectrolyte chains and the pair correlation function between monomers from different polyelectrolyte ligands are analyzed carefully. Also, electrostatic correlations, manifested as the bridging through trivalent counterions, are examined by identifying four states of trivalent counterions. Our simulation results may be useful for designing smart stimuli-responsive materials based on mixed polyelectrolyte coated surfaces. 相似文献
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We study the quasi-exactly solvable problems in relativistic quantum mechanics. We consider the problems for the two-dimensional Klein-Gordon and Dirac equations with equal vector and scalar potentials, and try to find the general form of the quasi-exactly solvable potential. After obtaining the general form of the potential, we present several examples to give the specific forms. In the examples, we show for special parameters the harmonic potential plus Coulomb potential, Killingbeck potential and a quartic potential plus Cornell potential are quasi-exactly solvable potentials. 相似文献
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采用分子动力学方法研究了平板聚两性离子刷的表面相行为.考察了不同价态反离子存在时,聚两性离子刷表面形貌随静电相互作用强度的演化.当静电作用逐渐增强时, 3种模拟系列下两性离子刷都发生微相分离形成了钉扎状胶束结构.结合刷高、密度分布函数和主链单体对关联函数,分析了胶束尺寸和胶束内粒子堆积状态的变化.通过统计反离子在刷内的4种状态,揭示了单价和多价反离子在诱导聚两性离子刷相结构上的差异. 相似文献
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Diffusion activation energy versus the favourable energy in two-order-parameter model:A molecular dynamics study of liquid Al 下载免费PDF全文
In the present work, we find that both diffusion activation energy Ea(D) and Ea(Sex) increase linearly with pressure and have the same slope (0.022±0.001 eV/GPa) for liquid Al. The temperature and pressure dependence of excess entropy is well fitted by the expression -Sex(T,P)/kB=a(P)+b(P)T+c(P)exp(Ef/kBT), which together with the small ratio of Ef/kBT leads to the relationship of excess entropy to temperature and pressure, i.e. Sex≈-cEf/T, where c is about 12 and Ef (=Δ E-PΔV) is the favourable energy. Therefore, there exists a simple relation between Ea(Sex) and Ef, i.e. Ea(Sex)≈cEf. 相似文献
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