Combined Mixing and Dynamical Origins of T g Alterations Near Polymer–Polymer Interfaces
Combined Mixing and Dynamical Origins of T g Alterations Near Polymer–Polymer Interfaces
复制标题
聚合物-聚合物界面附近 Tg 变化的组合混合和动力学起源
DOI：
10.1021/acs.macromol.2c01621
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发表时间：
2023
期刊：
影响因子：
5.5
通讯作者：
Simmons, David S.
中科院分区：
文献类型：
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作者：
Ghanekarade, Asieh;Simmons, David S.
嵌段共聚物和层状聚合物中玻璃形成行为的改变在多大程度上是由局部成分混合引起的，而不是由长期的动力学关联引起的，这一点一直没有得到解决。在这里，我们在模型聚合物-聚合物界面上进行分子动力学模拟，以了解这些机制的相对作用。结果表明，从高χ区（近界面变化纯粹由动力梯度效应驱动）到低χ区（局部混合和动力相关都起作用）之间存在交叉。观察到梯度范围不对称，超过组成梯度范围，并随着χ的减小而适度增长。这些结果为纳米结构聚合物的局部动力学设计提供了新的见解。他们还强调了许多研究之间明显的两分法，包括我们的研究，指出梯度范围在10纳米左右，而第二组研究报告的范围更大，达到数百纳米。
The extent to which altered glass formation behavior in block copolymers and layered polymers results from local compositional mixing vs from longer-ranged dynamical correlations has long been unresolved. Here, we perform molecular dynamics simulations at model polymer–polymer interfaces to understand the relative roles of these mechanisms. Results indicate a crossover from the high-χ regime, where near-interfaceTgalterations are driven purely by dynamical gradient effects, to the low-χ regime, where both local mixing and dynamical correlations play a role. ObservedTggradient ranges are asymmetric, exceed the range of composition gradients, and modestly grow with decreasing χ. These results provide new insight into the design of nanostructured polymers with targeted local dynamics. They also emphasize an apparent dichotomy between many studies, including ours, pointing towardTggradient ranges on the order of 10 nm, and a second set of studies reporting on longer ranges up to hundreds of nanometers.