Dynamic self-consistent field theory for unentangled homopolymer fluids.
Dynamic self-consistent field theory for unentangled homopolymer fluids.
复制标题
非纠缠均聚物流体的动态自洽场论。
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Y. Shnidman
中科院分区：
文献类型：
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作者：
M. Mihajlovic;T. Lo;Y. Shnidman
我们提出了一种动态自洽场(DSCF)理论的晶格形式，该理论能够解决非均质、可压缩熔体和无缠结均聚物链的共混体系中的界面结构、动力学和流变学。流体中所有库恩段与相邻段和壁相互作用的联合概率分布由自由段仅与自洽确定的外部势场相互作用的一体概率的乘积近似。流对理想链构象的影响在Peterlin近似下用有限可扩展的非线性弹性哑铃来模拟，并与随机游动中的步进概率有关。自由链段和步进概率在自洽场中产生链构象的统计权重，并确定链段的局部体积分数。单位晶胞间的通量平衡给出了库恩长度尺度上自由段几率和动量密度演化的平均场输运方程。对通量的扩散和粘性贡献来自分段跳跃被模拟为马尔可夫过程，过渡率反映了分段相互作用、动能和对流动下自由能的熵贡献的变化。我们应用DSCF方程来研究剪切平面通道中包含单组分熔体或相分离的双组分混合物的暂态和稳态界面结构、流动和流变性。
We present a lattice formulation of a dynamic self-consistent field (DSCF) theory that is capable of resolving interfacial structure, dynamics, and rheology in inhomogeneous, compressible melts and blends of unentangled homopolymer chains. The joint probability distribution of all the Kuhn segments in the fluid, interacting with adjacent segments and walls, is approximated by a product of one-body probabilities for free segments interacting solely with an external potential field that is determined self-consistently. The effect of flow on ideal chain conformations is modeled with finitely extensible, nonlinearly elastic dumbbells in the Peterlin approximation, and related to stepping probabilities in a random walk. Free segment and stepping probabilities generate statistical weights for chain conformations in a self-consistent field, and determine local volume fractions of chain segments. Flux balance across unit lattice cells yields mean field transport equations for the evolution of free segment probabilities and of momentum densities on the Kuhn length scale. Diffusive and viscous contributions to the fluxes arise from segmental hops modeled as a Markov process, with transition rates reflecting changes in segmental interaction, kinetic energy, and entropic contributions to the free energy under flow. We apply the DSCF equations to study both transient and steady-state interfacial structure, flow, and rheology in a sheared planar channel containing either a one-component melt or a phase-separated, two-component blend.