Department of Chemical, Materials and Industrial Production, Università degli Studi di Napoli Federico II, P.le Tecchio 80, 80125 Napoli, Italy.
Soft Matter. 2019 Feb 6;15(6):1396-1404. doi: 10.1039/c8sm01959b.
Aqueous solutions of tri-block co-polymer surfactants are able to aggregate into a rich variety of microstructures, which can exhibit different rheological behaviors. In this work, we study the diversity of structures detected in aqueous solutions of Pluronic L64 at various concentrations and temperatures by experimental rheometry and dissipative particle dynamics (DPD) simulations. Mixtures of Pluronic L64 in water (ranging from 0 to 90 wt% Pluronic L64) have been studied in both linear and non-linear regimes by oscillatory and steady shear flow. The measurements allowed for the determination of a complete rheological phase diagram of the Pluronic L64-water system. The linear and non-linear regimes have been compared to equilibrium and non-equilibrium DPD bulk simulations of similar systems obtained by using the software LAMMPS. The molecular results are capable of reproducing the equilibrium structures, which are in complete agreement with the ones predicted through experimental linear rheology. The simulations also depict micellar microstructures after long time periods when a strong flow is applied. These structures are directly compared, from a qualitative point of view, with the corresponding experimental results and differences between the equilibrium and non-equilibrium phase diagrams are highlighted, proving the capability of detecting morphological changes caused by deformation in both experiments and DPD simulations. The effect of temperature on the rheology of the systems has been eventually investigated and compared with the already existing non-rheological phase diagram.
三嵌段共聚物表面活性剂的水溶液能够聚集形成丰富多样的微观结构，从而表现出不同的流变行为。在这项工作中，我们通过实验流变学和耗散粒子动力学（DPD）模拟研究了不同浓度和温度下 Pluronic L64 水溶液中检测到的结构多样性。通过振荡和稳态剪切流研究了水（Pluronic L64 含量范围为 0 至 90wt%）中的 Pluronic L64 混合物。测量结果允许确定 Pluronic L64-水系统的完整流变相图。将线性和非线性区域与使用 LAMMPS 软件获得的类似系统的平衡和非平衡 DPD 体模拟进行了比较。分子结果能够再现平衡结构，这些结构与通过实验线性流变学预测的结构完全一致。模拟还描绘了在施加强流后很长时间后的胶束微观结构。从定性的角度来看，这些结构直接与相应的实验结果进行了比较，并且突出了平衡和非平衡相图之间的差异，证明了在实验和 DPD 模拟中检测由变形引起的形态变化的能力。最终还研究了温度对系统流变性能的影响，并与已有的非流变相图进行了比较。
