Cheng Stephen Z D, Lotz Bernard
Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, OH 44325-3909, USA.
Philos Trans A Math Phys Eng Sci. 2003 Mar 15;361(1804):517-36; discussion 536-7. doi: 10.1098/rsta.2002.1148.
Thermodynamically, polymer crystallization is a first-order transition that involves overcoming an energy barrier. Building a molecular kinetic model that links this macroscopic concept with experimental observations has been and still remains a difficult issue. It requires a physical picture that can show how a three-dimensionally random linear macromolecule is converted to a chain-folded crystalline state despite the loss of entropy in the process. There are a number of dynamic molecular pathways during polymer crystallization, and previous analytical models have used a 'mean-field' approach. In polymer crystallization, every macromolecule has to go through several selection processes on different length- and time-scales. In this article, we try to identify these selection processes and lay down some basic principles of polymer crystallization. Experimental observations on stem configurations, helical conformations, crystal structures, fold lengths, global macromolecular conformations and lamellar single-crystal morphologies have been used as probes to identify these selection processes.
从热力学角度来看，聚合物结晶是一个涉及克服能垒的一级转变过程。构建一个将这一宏观概念与实验观测联系起来的分子动力学模型一直以来都是且仍然是一个难题。这需要一个物理图像，以展示一个三维随机线性大分子如何尽管在此过程中熵减少但仍转变为链折叠晶体状态。在聚合物结晶过程中有许多动态分子途径，并且先前的分析模型采用了“平均场”方法。在聚合物结晶中，每个大分子都必须在不同的长度和时间尺度上经历几个选择过程。在本文中，我们试图识别这些选择过程并阐述聚合物结晶的一些基本原理。关于茎状构型、螺旋构象、晶体结构、折叠长度、整体大分子构象和片层单晶形态的实验观测已被用作识别这些选择过程的探针。
