Universality of Block Copolymer Melts
Universality of Block Copolymer Melts
复制标题
DOI：
10.1103/physrevlett.113.068302
复制
发表时间：
2014-08-08
影响因子：
8.6
通讯作者：
Morse, David C.
中科院分区：
文献类型：
--
作者：
Glaser, Jens;Medapuram, Pavani;Morse, David C.
对对称二嵌段共聚物的五种不同粗粒度模型的模拟进行了比较，以证明自由能和有序-无序过渡（ODT）对不变性聚合度(N)的普遍（即与模型无关）依赖性。在ODT接近Fredrickson-Helfand （FH）理论预测的(N)的实际值大于或类似于10(4)，但显著超过FH在大多数实验特征的较低值预测。跳频理论在中等(N) / bar条件下失效，因为竞争相在ODT附近发生了强烈的偏析，违反了弱偏析的基本假设。
Simulations of five different coarse-grained models of symmetric diblock copolymers are compared to demonstrate a universal (i.e., model-independent) dependence of the free energy and order-disorder transition (ODT) on the invariant degree of polymerization (N) over bar. The actual values of chi N at the ODT approach predictions of the Fredrickson-Helfand (FH) theory for (N) over bar greater than or similar to 10(4) but significantly exceed FH predictions at lower values characteristic of most experiments. The FH theory fails for modest (N) over bar because the competing phases become strongly segregated near the ODT, violating an underlying assumption of weak segregation.