Jiang Xiaoming, Reiter Günter, Hu Wenbing
Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , 210093 Nanjing, China.
Institute of Physics, Faculty of Mathematics and Physics, Albert-Ludwig-University of Freiburg , Hermann-Herder-Str. 3, 79104 Freiburg, Germany.
J Phys Chem B. 2016 Jan 28;120(3):566-71. doi: 10.1021/acs.jpcb.5b09324. Epub 2016 Jan 13.
Chain-folding is a habit of polymer crystallization, which yields limited lamellar thickness of polymer crystals and thus determines their thermodynamic stability. We performed dynamic Monte Carlo simulations of a lattice polymer model with chain-folded lamellar crystal growth stopped by a critical spacing of two parallel-oriented bars. We confirmed the critical spacing as minimum lamellar thickness (lmin) proposed previously in the Lauritzen-Hoffman (LH) model; however, the temperature dependence of excess lamellar thickness beyond lmin appears opposite to the prediction of the LH model. Moreover, it reproduces Strobl et al.'s experimental observations, but our lattice-model approach rules out any mesophase hypothesis. We proposed a kinetic model combining intramolecular secondary nucleation and stem elongation to explain this temperature-dependence behavior, which reconciles the controversial arguments on the microscopic mechanism of lamellar crystal growth of polymers.
链折叠是聚合物结晶的一种习性，它导致聚合物晶体的片晶厚度有限，从而决定了它们的热力学稳定性。我们对一个晶格聚合物模型进行了动态蒙特卡罗模拟，链折叠片晶晶体生长因两个平行取向杆的临界间距而停止。我们证实了临界间距即为之前劳里茨森 - 霍夫曼（LH）模型中提出的最小片晶厚度（lmin）；然而，超过lmin的过量片晶厚度的温度依赖性似乎与LH模型的预测相反。此外，它再现了施特罗布尔等人的实验观察结果，但我们的晶格模型方法排除了任何中间相假设。我们提出了一个结合分子内二次成核和链段伸长的动力学模型来解释这种温度依赖性行为，这调和了关于聚合物片晶晶体生长微观机制的争议性观点。
