Livadaru Lucian, Kovalenko Andriy
National Institute for Nanotechnology, National Research Council of Canada, W6-010, ECERF Building, 9107-116 Street, Edmonton, AB, Canada, T6G 2V4.
J Phys Chem B. 2005 Jun 2;109(21):10631-9. doi: 10.1021/jp044654w.
We propose a self-consistent molecular theory of conformational properties of flexible polymers in melts and solutions. The method employs the polymer reference interaction site model for the intermolecular correlations and the Green function technique for the intramolecular correlations. We demonstrate this method on n-alkane molecules in different environments: water, hexane, and in melt, corresponding to poor, good, and theta condition, respectively. The numerical results of the intramolecular correlation function, the radius of gyration, and the characteristic ratio of a polymer chain are indicative of conformational changes from one environment to another and are in agreement with other findings in the literature. Scaling laws for the chain size with respect to the number of monomers are discussed. We show results for the intra- and intermolecular correlation functions and the medium-induced potential. We also extract the Kuhn length and the characteristic ratio for the infinite chain limit for melts. The latter is compared to the experimental results and computer simulation. The conformational free energy per monomer in different solvents is calculated. Our treatment can be generalized readily to other polymer-solvent systems, for example, those containing branched copolymers and polar solvents.
我们提出了一种关于柔性聚合物在熔体和溶液中构象性质的自洽分子理论。该方法采用聚合物参考相互作用位点模型来描述分子间相关性，并用格林函数技术来描述分子内相关性。我们在不同环境下的正构烷烃分子上演示了此方法：水、己烷以及熔体，分别对应不良溶剂、良溶剂和θ条件。聚合物链的分子内相关函数、回转半径和特征比的数值结果表明了从一种环境到另一种环境的构象变化，并且与文献中的其他发现一致。讨论了链尺寸相对于单体数量的标度律。我们展示了分子内和分子间相关函数以及介质诱导势的结果。我们还提取了熔体中无限链极限的库恩长度和特征比。将后者与实验结果和计算机模拟进行了比较。计算了不同溶剂中每个单体的构象自由能。我们的处理方法可以很容易地推广到其他聚合物 - 溶剂体系，例如那些含有支化共聚物和极性溶剂的体系。
