Universality of Viscoelastic Phase Separation in Dynamically Asymmetric Polymer Mixture

到目前为止，人们一直认为聚合物体系与经典流体属于同一动态普适性类，更确切地说，是霍亨伯格-哈尔珀林记号中的所谓模型H。然而，我们最近的实验研究有力地表明，至少在实际意义上，聚合物溶液的行为不能用任何传统的动态普适类来解释。高分子链的拓扑特性导致了聚合物的慢分子运动和粘弹性效应。聚合物和溶剂之间分子动力学的不对称性导致了应力场和有序参数之间的强烈动力学耦合。这导致了平衡临界动力学的有序参数涨落的粘弹性抑制，以及不稳定状态下具有粘弹性驱动形态的异常相分离。粘弹性效应的松弛性质违背了生长模式的自相似性。除了静态对称性、成分对称性之外，还应引入动态对称性的新概念。

It has so far been believed that polymer systems belong to the same dynamic universality class as classical fluids, nemely, the so-called model H in the Hohenberg-Halperin notation. However, our recent experimental studies strongly indicate that behavior fo polymer solutions can be explained by none of the conventional dynamic universality classes at least in the practical sense. Topological characteristics of polymer chains induces the slow molecular motion of polymer and the viscoelastic effect. The asymmetry in molecular dynamics between polymer and solvent leads to the strong kinetic coupling between the stress field and the order parameter. This causes the viscoelastic suppression of the order parameter fluctuation for equlibrium critical dynamics and unusual phase separation having a viscoelastically driven morphology for unstable states. The relaxational nature of viscoelastic effect violates the selfsimilarity of the growing pattern. A new concept of dynamic symmetry should introduced in addition to the static, composition symmetry.