Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan.
Langmuir. 2010 Apr 20;26(8):5374-81. doi: 10.1021/la903790g.
A new transient network theory is developed to study the rheological properties of entangled wormlike micelles. The dynamic mechanical moduli are calculated on the basis of the model network in which local structure of the wormlike micelles is represented by the entangled loops. These loops interact with each other by statistical force due to the topological constraints. They are assumed to pass through each other within a finite time to release the internal stress (phantom chain-crossing model). The high frequency plateau modulus G(infinity) and the relaxation time tau as functions of the micellar concentration are calculated and compared with the experimental data on the aqueous solutions of cetyltrimethylammonium bromide (CTAB) mixed with ionic aromatic compound sodium salicylate (NaSal). It turns out that creation and annihilation of the entanglements are strongly coupled to the topological force. The rheological relaxation time decreases with the concentration of the micelles because the average radius (correlation length xi) of the entangled loops, and their contour length L decrease with the CTAB concentration. Hence, the topological force is amplified by the increase in the concentration and, as a result, accelerates the stress relaxation by chain-crossing.
一种新的瞬态网络理论被发展用来研究缠结的蠕虫状胶束的流变性质。基于模型网络计算动态力学模量，其中蠕虫状胶束的局部结构由缠结环表示。由于拓扑约束，这些环通过统计力相互作用。假设它们在有限的时间内相互穿过，以释放内部应力（幻影链交叉模型）。计算了高频率平台模量 G(无穷大)和松弛时间 tau 作为胶束浓度的函数，并与十六烷基三甲基溴化铵 (CTAB) 与离子芳香族化合物水杨酸钠 (NaSal) 的水溶液的实验数据进行了比较。结果表明，缠结的产生和消失与拓扑力强烈耦合。流变松弛时间随胶束浓度的降低而降低，因为缠结环的平均半径（相关长度 xi）及其轮廓长度 L 随 CTAB 浓度的降低而降低。因此，拓扑力随浓度的增加而放大，从而通过链交叉加速应力松弛。
