Center of Smart Interfaces - Technische Universität Darmstadt, Petersenstr. 32, 64287 Darmstadt, Germany.
Phys Chem Chem Phys. 2012 Sep 14;14(34):11896-903. doi: 10.1039/c2cp40735c. Epub 2012 Jun 22.
In this work we study the transferability of systematically coarse-grained (CG) potentials for polymer-additive systems. The CG nonbonded potentials between the polymer (atactic polystyrene) and three different additives (ethylbenzene, methane and neopentane) are derived using the Conditional Reversible Work (CRW) method, recently proposed by us [Brini et al., Phys. Chem. Chem. Phys., 2011, 13, 10468-10474]. A CRW-based effective pair potential corresponds to the interaction free energy between the two atom groups of an atomistic parent model that represent the coarse-grained interaction sites. Since the CRW coarse-graining procedure does not involve any form of parameterisation, thermodynamic and structural properties of the condensed phase are predictions of the model. We show in this work that CRW-based CG models of polymer-additive systems are capable of predicting the correct structural correlations in the mixture. Furthermore, the excess chemical potentials of the additives obtained with the CRW-based CG models and the united-atom parent models are in satisfactory agreement and the CRW-based CG models show a good temperature transferability. The temperature transferability of the model is discussed by analysing the entropic and enthalpic contributions to the excess chemical potentials. We find that CRW-based CG models provide good predictions of the excess entropies, while discrepancies are observed in the excess enthalpies. Overall, we show that the CRW CG potentials are suitable to model structural and thermodynamic properties of polymer-penetrant systems.
在这项工作中，我们研究了系统地粗粒化（CG）势在聚合物添加剂体系中的可转移性。使用我们最近提出的条件可逆工作（CRW）方法[Brini 等人，Phys. Chem. Chem. Phys.，2011，13，10468-10474]，推导出聚合物（无规聚苯乙烯）和三种不同添加剂（乙基苯、甲烷和新戊烷）之间的 CG 非键相互作用势。基于 CRW 的有效对势对应于表示粗粒化相互作用位点的原子型母体模型的两个原子组之间的相互作用自由能。由于 CRW 粗粒化过程不涉及任何形式的参数化，因此凝聚相的热力学和结构性质是模型的预测。我们在这项工作中表明，聚合物添加剂体系的基于 CRW 的 CG 模型能够预测混合物中的正确结构相关性。此外，基于 CRW 的 CG 模型和统一原子母体模型获得的添加剂的超额化学势非常吻合，并且 CRW 基于 CG 模型表现出良好的温度可转移性。通过分析超额化学势的熵和焓贡献来讨论模型的温度可转移性。我们发现，基于 CRW 的 CG 模型能够很好地预测超额熵，而超额焓则存在差异。总的来说，我们表明，CRW CG 势适合于模拟聚合物渗透剂体系的结构和热力学性质。
