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首页> 外文期刊>The Journal of Chemical Physics >Monte Carlo simulation of a film growth with reactive hydrophobic, polar, and aqueous components by a covalent bond fluctuating model
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Monte Carlo simulation of a film growth with reactive hydrophobic, polar, and aqueous components by a covalent bond fluctuating model

机译：通过共价键波动模型对具有反应性疏水，极性和水性组分的薄膜生长进行蒙特卡洛模拟

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Using a bond fluctuating model (BFM), Monte Carlo simulations are performed to study the film growth in a mixture of reactive hydrophobic (H) and hydrophilic (P) groups in a simultaneous reactive and evaporating aqueous (A) solution on a simple three dimensional lattice. In addition to the excluded volume, short range phenomenological interactions among each constituents and kinetic functionalities are used to capture their major characteristics. The simulation involves thermodynamic equilibration via stochastic movement of each constituent by Metropolis algorithm as well as cross-linking reaction among constituents with evaporating aqueous component. The film thickness (h) and its interface width (W) are examined with a reactive aqueous solvent for a range of temperatures (T). Results are compared with a previous study [Yang Macromol. Theory Simul. 15, 263 (2006)] with an effective bond fluctuation model (EBFM). Simulation data show a much slower power-law growth for h and W with BFM than that with EBFM. With BFM, growth of the film thickness can be described by h proportional to t(gamma), with a typical value gamma(1)approximate to 0.97 in initial time regime followed by gamma(2)approximate to 0.77 at T=5, for example. Growth of the interface width can also be described by a power law, W proportional to t(beta), with beta(1)approximate to 0.40 initially and beta(2)approximate to 0.25 in later stage. Corresponding values of the exponents with EBFM are much higher, i.e., gamma(1)approximate to 1.84, gamma(2)approximate to 1.34 and beta(1)approximate to 1.05, beta(2)approximate to 0.60 at T=5. Correct restrictions on the bond length with the excluded volume used with BFM are found to have a greater effect on steady-state film thickness (h(s)) and the interface width (W-s) at low temperatures than that at high temperatures. The relaxation patterns of the interface width with BFM seem to change noticeably from those with EBFM. A better relaxed film with a smoother surface is thus achieved by the improved cross-linking covalent bond fluctuation model which is more realistic in capturing appropriate details of systems such as polyurethane film. The steady-state film thickness increases monotonically with the temperature possibly with two logarithmic dependences. The equilibrium interface width shows a nonmonotonic dependence: on increasing the temperature, W-s seems to increase slowly before it begins to decay W-s=4.12-1.39 ln(T). (c) 2007 American Institute of Physics.
机译：使用键波动模型（BFM），进行Monte Carlo模拟，以研究在简单的三维上同时存在反应性和蒸发性水溶液（A）的情况下，反应性疏水性（H）和亲水性（P）基团的混合物中薄膜的生长格子。除了排除的体积外，每种成分之间的短距离现象学相互作用和动力学功能还用于捕获其主要特征。该模拟涉及通过Metropolis算法通过各组分的随机运动进行热力学平衡，以及组分之间与蒸发的水相组分之间的交联反应。用反应性水性溶剂在一定温度（T）范围内检查膜厚度（h）及其界面宽度（W）。将结果与先前的研究进行比较[Yang Macromol。理论模拟。 15，15，263（2006）]中包含有效的债券涨落模型（EBFM）。仿真数据显示，BFM的h和W的幂律增长比EBFM慢得多。对于BFM，膜厚的增长可以用与t（γ）成正比的h来描述，典型值gamma（1）在初始时间范围内约为0.97，然后在T = 5时的gamma（2）约为0.77，对于例。界面宽度的增长也可以通过幂律来描述，W与t（β）成比例，β（1）最初约为0.40，β（2）以后约为0.25。与EBFM的指数对应的值要高得多，即在T = 5时，γ（1）约1.84，γ（2）约1.34，β（1）约1.05，β（2）约0.60。与在高温下相比，在BFM中使用正确的限制键长和排除体积对低温下的稳态膜厚（h（s））和界面宽度（W-s）产生更大的影响。 BFM界面宽度的弛豫模式似乎与EBFM相比明显改变。因此，通过改进的交联共价键波动模型，可以得到具有更平滑表面的更好松弛的薄膜，该模型在捕获诸如聚氨酯薄膜之类的系统的适当细节时更为现实。稳态膜厚度随温度单调增加，可能有两个对数依赖性。平衡界面宽度显示出非单调依赖性：随着温度的升高，W-s在开始衰减之前似乎缓慢增加W-s = 4.12-1.39 ln（T）。 （c）2007年美国物理研究所。

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