Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA.
Soft Matter. 2014 Apr 28;10(16):2889-98. doi: 10.1039/c3sm53113a.
The complex, nonlinear flow behavior of soft materials transcends industrial applications, smart material design and non-equilibrium thermodynamics. A long-standing, fundamental challenge in soft-matter science is establishing a quantitative connection between the deformation field, local microstructure and macroscopic dynamic flow properties i.e., the rheology. Here, a new experimental method is developed using simultaneous small angle neutron scattering (SANS) and nonlinear oscillatory shear rheometry to investigate the spatiotemporal microstructure evolution of a polymer-like micellar (PLM) solution. We demonstrate the novelty of nonlinear oscillatory shear experimental methods to create and interrogate metastable material states. These include a precursory state to the shear banded condition as well as a disentangled, low viscosity state with an inhomogeneous supra-molecular microstructure flowing at high shear rates. This new experimental evidence provides insight into the complexities of the shear banding phenomenon often observed in sheared complex fluids and provides valuable data for quantitatively testing non-equilibrium theory.
软物质的复杂非线性流动行为超越了工业应用、智能材料设计和非平衡热力学。软物质科学中长期存在的一个基本挑战是在变形场、局部微观结构和宏观动态流动性质（即流变学）之间建立定量联系。在这里，开发了一种新的实验方法，使用同步小角中子散射（SANS）和非线性振荡剪切流变仪来研究聚合物样胶束（PLM）溶液的时空微观结构演化。我们展示了非线性振荡剪切实验方法的新颖性，以创建和探测亚稳材料状态。这些状态包括剪切带条件的前兆状态以及解缠、低粘度状态，具有非均匀的超分子微观结构，在高剪切速率下流动。这种新的实验证据深入了解了在剪切复杂流体中经常观察到的剪切带现象的复杂性，并为定量测试非平衡理论提供了有价值的数据。
