Ma Yu, Zha Liyun, Hu Wenbing, Reiter Günter, Han Charles C
Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Jun;77(6 Pt 1):061801. doi: 10.1103/PhysRevE.77.061801. Epub 2008 Jun 2.
We report dynamic Monte Carlo simulations of immiscible binary polymer blends, which exhibit weakly enhanced crystal nucleation near interfaces between two phase-separated polymers. We found that this enhancement is not accompanied by any preferred crystal orientation, implying its origin is mainly of enthalpic rather than entropic nature. Mean-field theory of polymer blends predicts that for immiscible polymers the melting point of the crystallizable component increases upon dilution in the other component, while it normally decreases for miscible blends. A local dilution is forced to occur at the diffuse interface of immiscible polymers; therefore the melting point of crystallizable polymers rises, which, in turn, enhances the thermodynamic driving force for crystal nucleation near the interface.
我们报告了不混溶二元聚合物共混物的动态蒙特卡罗模拟，该共混物在两个相分离聚合物之间的界面附近表现出微弱增强的晶体成核现象。我们发现这种增强并不伴随着任何优先的晶体取向，这意味着其起源主要是焓性的而非熵性的。聚合物共混物的平均场理论预测，对于不混溶聚合物，可结晶组分在被另一组分稀释时熔点会升高，而对于混溶共混物，其熔点通常会降低。在不混溶聚合物的扩散界面处会强制发生局部稀释；因此，可结晶聚合物的熔点升高，这反过来又增强了界面附近晶体成核的热力学驱动力。
