Qi Shuanhu, Yan Dadong
Beijing National Laboratory for Molecular Sciences (BNLMS), Joint Laboratory of Polymer Science and Materials Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
J Chem Phys. 2008 Nov 28;129(20):204902. doi: 10.1063/1.3020355.
The effect of polydispersity on nucleation in a metastable mixture of polydisperse polymer A and monodisperse polymer B is studied using self-consistent field theory. We adopt the continuous Schulz chain length distribution to describe the polydispersity of species A. The results show that the free energy barrier, as well as many other properties of the critical nucleus, is sensitive to the polydispersity, especially in the highly polydisperse case. This should be attributed to the fact that longer chains have stronger tendencies toward nucleation. As a result, the distribution of the volume fraction as a function of chain length in the nucleus becomes different from that in the bulk. The chain length, which corresponds to the maximum contribution to the volume fraction in the nucleus, becomes larger than the number-average chain length. Meanwhile, the interface between the critical nucleus and the parent metastable bulk phase broadens. This phenomenon is obvious when the polydispersity is high.
利用自洽场理论研究了多分散聚合物A和单分散聚合物B的亚稳混合物中多分散性对成核的影响。我们采用连续的舒尔茨链长分布来描述物种A的多分散性。结果表明，自由能垒以及临界核的许多其他性质对多分散性敏感，特别是在高度多分散的情况下。这应归因于较长链具有更强的成核倾向。因此，核中体积分数随链长的分布与本体中的不同。对应于核中体积分数最大贡献的链长变得大于数均链长。同时，临界核与母体亚稳本体相之间的界面变宽。当多分散性较高时，这种现象很明显。
