Computer Simulation of Surface‐Initiated Controlled Radical Polymerization: Effect of Free‐Monomer Model on Brush Properties
Computer Simulation of Surface‐Initiated Controlled Radical Polymerization: Effect of Free‐Monomer Model on Brush Properties
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DOI：
10.1002/mats.201900033
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发表时间：
2019-07
影响因子：
1.4
通讯作者：
Salomon Turgman‐Cohen;J. Genzer
中科院分区：
文献类型：
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作者：
Salomon Turgman‐Cohen;J. Genzer
使用键涨落模型(BFM)进行了蒙特卡罗模拟，探讨了自由单体模型在平板表面引发控制聚合中的作用。三种自由单体模型在两个方面有所不同：1)它们排除自由单体/聚合物链段之间的体积相互作用的程度；2)模拟过程中单体的可用性(有限或无限)。在显式单体(EM)模型中，自由单体表现为单个BFM型单元。在幻影单体(PM)模型中，自由单体的行为类似于EM模型中的那些，但缺乏与增长的聚合物的排除体积相互作用。在隐式单体(IM)模型中，模拟框中不包括显式单体；只要活性链端附近有可用的空间，聚合物就可以生长。结果表明，聚合物分子量分布的宽度从EM模型到PM模型再到IM模型逐渐减小。在EM模型中，自由单体被排除在近表面区域之外，而在PM模型中则不是。由于排除了体积相互作用，EM模型往往会将刷子压缩到衬底上。最后，报道了聚合反应结束后多分散刷形状的松弛。
Monte Carlo simulation is employed using the bond‐fluctuation model (BFM) to explore the role of free‐monomer model on surface‐initiated controlled polymerization from flat substrates. Three free‐monomer models differ in two aspects: 1) their extent of excluded volume interactions between free‐monomer/polymer segments and 2) monomer availability (finite or infinite) during the simulation. In the explicit monomer (EM) model, free‐monomers behave as a single BFM‑type units. In the phantom monomer (PM) model, free‐monomers act analogously to those in the EM model but lack excluded volume interactions with the growing polymers. In the implicit monomer (IM) model, no explicit monomers are included in the simulation box; the polymers can grow as long as space is available near active chain‐ends. It is found that the breadth of the molecular weight distribution of the grown polymers decreases from EM, to PM, to IM models. With the EM model, free‐monomers are excluded from the near‐surface region, while with the PM model they are not. Due to its excluded volume interactions, the EM model tends to compress the brush against the substrate. Finally, the relaxation of the shape of a polydisperse brush after the polymerization reaction ends has been reported.