Hoy Robert S, Karayiannis Nikos Ch
Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Jul;88(1):012601. doi: 10.1103/PhysRevE.88.012601. Epub 2013 Jul 2.
We study a simple bead-spring polymer model exhibiting competing crystallization and glass transitions. Constant-pressure molecular dynamics simulations are employed to study phase behavior and morphological order. For adequately slow quench rates, chain systems exhibit a first-order phase transition (crystallization) below a critical temperature T=T(cryst). We observe the formation of close-packed crystallites of FCC and/or HCP order, separated by domain walls, twin defects, and amorphous regions. Such crystal structures closely resemble the corresponding ordered morphologies of athermal polymer packings: fully flexible chains retain random-walk-like configurations in the crystalline state and do not form lamellae, while semiflexible chains do form lamellae. The model presented here is well suited to the modeling of granular and colloidal polymers, in particular for elucidating the factors that dictate the formation of specific ordered morphologies.
我们研究了一个展现出竞争结晶和玻璃化转变的简单珠-弹簧聚合物模型。采用恒压分子动力学模拟来研究相行为和形态有序性。对于足够慢的淬火速率，链系统在临界温度(T = T_{cryst})以下表现出一级相变（结晶）。我们观察到由畴壁、孪晶缺陷和非晶区域分隔的面心立方（FCC）和/或六方密堆积（HCP）有序的密堆积微晶的形成。这种晶体结构与无热聚合物堆积的相应有序形态非常相似：完全柔性链在结晶态保留类似随机游走的构型且不形成片晶，而半柔性链确实会形成片晶。这里提出的模型非常适合用于模拟粒状和胶体聚合物，特别是用于阐明决定特定有序形态形成的因素。
