Shear flow behaviors of rod-coil diblock copolymers in solution: A nonequilibrium dissipative particle dynamics simulation
Shear flow behaviors of rod-coil diblock copolymers in solution: A nonequilibrium dissipative particle dynamics simulation
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DOI：
10.1063/1.4982938
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发表时间：
2017-05
影响因子：
4.4
通讯作者：
Pengxiang Xu;Jiaping Lin;Liquan Wang;Liangshun Zhang
中科院分区：
文献类型：
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作者：
Pengxiang Xu;Jiaping Lin;Liquan Wang;Liangshun Zhang
我们采用非平衡耗散粒子动力学方法研究了棒-线圈二嵌段共聚物在溶液中的剪切流行为。研究了共聚物浓度和分子结构对流变学的影响。模拟结果表明，通过增加共聚物浓度，当形态从胶束转变为凝胶时，剪切流行为从牛顿流变为非牛顿流。对于非牛顿体系，我们发现粘度与剪切速率的曲线分为三个区域，即剪切稀化区I、平台区II和剪切稀化区III。从物理起源来看，三区域行为由杆和线圈块的不同流动行为及其响应剪切场的不同时间尺度控制。此外，通过调整分子结构，模拟结果表明，区域 I 和区域 III 的斜率分别受到棒和线圈块长度的影响。
We employed the nonequilibrium dissipative particle dynamics method to study the shear flow behaviors of rod-coil diblock copolymers in solutions. The effects of copolymer concentrations and molecular architecture on the rheology are investigated. The simulated results show that the shear flow behaviors change from Newtonian to non-Newtonian when the morphologies transform from micelles to gels by increasing the copolymer concentrations. For the non-Newtonian systems, it was found that the curve of the viscosity versus shear rate is divided into three regions, that is, shear thinning region I, platform region II, and shear thinning region III. From the physical origin, the three-region behavior is governed by the distinct flow behaviors of the rod and coil blocks and their different time scale in response to the shear field. Additionally, by tuning the molecular architectures, the simulated results reveal that the slopes in region I and region III are influenced by the length of rod and coil blocks, respe...