Canonical and microcanonical analysis of nongrafted homopolymer adsorption by an attractive substrate.
Canonical and microcanonical analysis of nongrafted homopolymer adsorption by an attractive substrate.
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DOI：
10.1063/1.3273418
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发表时间：
2009-12
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影响因子：
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通讯作者：
Lei Wang;Tao Chen;Xiangsong Lin;Yuan Liu;Haojun Liang
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文献类型：
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作者：
Lei Wang;Tao Chen;Xiangsong Lin;Yuan Liu;Haojun Liang
采用非格子Monte Carlo模拟和复制交换方法，从正则和微正则两个角度研究了非接枝均聚物在有吸引力的基底上的吸附行为.吸附转变被确定从典型的比热峰，并与传统的聚合物吸附与锚定在基板的表面上的一端。从微正则系综中典型的“回弯效应”和负比热来看，当吸附较强时，该跃迁为类一级跃迁。然而，当吸附强度变得足够弱时，它变成二级。进一步的研究表明，对于由有限数量的单体组成的链，这种转变的类型成为一级或二级的，不仅取决于单体-单体和单体-底物之间的相互作用，而且对它被限制在差距的宽度。
Using the off-lattice Monte Carlo simulation and replica-exchange method, we studied the behavior of nongrafted homopolymer adsorption by an attractive substrate from both the canonical and the microcanonical views. An adsorption transition is identified from the peak in canonical specific heat and compared with the conventional polymer adsorption with one end anchored on the surface of the substrate. Judging from the typical "backbending effect" and the negative specific heat in microcanonical ensemble, the transition is first-order-like when adsorption is relatively strong. However, it becomes second-order-like when the strength of adsorption becomes weak enough. Further study reveals that for a chain consisting of a limited number of monomers, the type of this transition becoming either first- or second-order-like depends not only on the interplay between monomer-monomer and monomer-substrate interaction, but also on the width of the gap in which it is confined.