Moreno Angel J, Colmenero Juan
Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain.
J Chem Phys. 2006 May 14;124(18):184906. doi: 10.1063/1.2198202.
We present simulations on a binary blend of bead-spring polymer chains. The introduction of monomer size disparity yields very different relaxation times for each component of the blend. Competition between two different arrest mechanisms, namely, bulklike dynamics and confinement, leads to an anomalous relaxation scenario for the fast component, characterized by sublinear time dependence for mean squared displacements, or logarithmic decay and convex-to-concave crossover for density-density correlators. These anomalous dynamic features, which are observed over time intervals extending up to 4 decades, strongly resemble predictions of mode coupling theory for nearby higher-order transitions. Chain connectivity extends anomalous relaxation over a wide range of blend compositions.
我们展示了对珠-弹簧聚合物链二元共混物的模拟。单体尺寸差异的引入使得共混物的每个组分具有非常不同的弛豫时间。两种不同的阻滞机制，即类本体动力学和受限效应之间的竞争，导致了快速组分出现反常弛豫情况，其特征为均方位移的次线性时间依赖性，或者密度-密度关联函数的对数衰减和从凸到凹的转变。这些反常动力学特征在长达4个数量级的时间间隔内都能观察到，与附近高阶转变的模式耦合理论预测非常相似。链连接性在很宽的共混物组成范围内扩展了反常弛豫。
