D'Adamo Giuseppe, Pelissetto Andrea, Pierleoni Carlo
SISSA, V. Bonomea 265, I-34136 Trieste, Italy.
Dipartimento di Fisica, Sapienza Università di Roma and INFN, Sezione di Roma I, P.le Aldo Moro 2, I-00185 Roma, Italy.
J Chem Phys. 2014 Dec 28;141(24):244905. doi: 10.1063/1.4904392.
A coarse-graining strategy, previously developed for polymer solutions, is extended here to mixtures of linear polymers and hard-sphere colloids. In this approach, groups of monomers are mapped onto a single pseudoatom (a blob) and the effective blob-blob interactions are obtained by requiring the model to reproduce some large-scale structural properties in the zero-density limit. We show that an accurate parametrization of the polymer-colloid interactions is obtained by simply introducing pair potentials between blobs and colloids. For the coarse-grained (CG) model in which polymers are modelled as four-blob chains (tetramers), the pair potentials are determined by means of the iterative Boltzmann inversion scheme, taking full-monomer (FM) pair correlation functions at zero-density as targets. For a larger number n of blobs, pair potentials are determined by using a simple transferability assumption based on the polymer self-similarity. We validate the model by comparing its predictions with full-monomer results for the interfacial properties of polymer solutions in the presence of a single colloid and for thermodynamic and structural properties in the homogeneous phase at finite polymer and colloid density. The tetramer model is quite accurate for q ≲ 1 (q=Rg/Rc, where Rg is the zero-density polymer radius of gyration and Rc is the colloid radius) and reasonably good also for q = 2. For q = 2, an accurate coarse-grained description is obtained by using the n = 10 blob model. We also compare our results with those obtained by using single-blob models with state-dependent potentials.
一种先前为聚合物溶液开发的粗粒化策略在此扩展到线性聚合物与硬球胶体的混合物。在这种方法中，单体组被映射到单个伪原子（一个团块）上，并且通过要求模型在零密度极限下重现一些大规模结构特性来获得有效的团块 - 团块相互作用。我们表明，通过简单地引入团块与胶体之间的对势，可以获得聚合物 - 胶体相互作用的精确参数化。对于将聚合物建模为四团块链（四聚体）的粗粒化（CG）模型，对势通过迭代玻尔兹曼反演方案确定，将零密度下的全单体（FM）对关联函数作为目标。对于更多数量n的团块，对势通过基于聚合物自相似性的简单可转移性假设来确定。我们通过将其预测结果与全单体结果进行比较来验证该模型，全单体结果涉及存在单个胶体时聚合物溶液的界面性质以及有限聚合物和胶体密度下均相中的热力学和结构性质。对于q≲1（q = Rg/Rc，其中Rg是零密度聚合物的回转半径，Rc是胶体半径），四聚体模型相当准确，对于q = 2也相当不错。对于q = 2，通过使用n = 10团块模型可获得准确的粗粒化描述。我们还将我们的结果与使用具有状态依赖势的单团块模型获得的结果进行比较。
