de Bruyn J R, Oppong F K
Department of Physics and Astronomy, University of Western Ontario, London, Canada.
Eur Phys J E Soft Matter. 2010 Jan;31(1):25-35. doi: 10.1140/epje/i2010-10545-y.
We study the microscopic viscoelastic properties and relaxation dynamics of solutions of a side-chain associative polymer, hydrophobically modified hydroxyethyl cellulose (hmHEC). Dynamic light scattering from small tracer particles suspended in the polymer solutions is used to determine their viscous and elastic moduli on the scale of the particles. Bulk-scale viscoelastic properties are measured by shear rheometry. The motion of the tracer particles in hmHEC is diffusive at short times and subdiffusive at intermediate and long times. The long-time subdiffusive motion was not observed in parallel experiments on unmodified HEC solutions, and is explained in terms of hindered reptation of the hydrophobically modified polymer chains in the associative network. Dynamic light scattering from the polymer molecules themselves shows that chain relaxation in hmHEC is dominated by slow concentration-dependent processes due to the large-scale associative network structure, while that in HEC is dominated by fast concentration independent Rouse-like dynamics.
我们研究了一种侧链缔合聚合物——疏水改性羟乙基纤维素（hmHEC）溶液的微观粘弹性性质和弛豫动力学。通过悬浮在聚合物溶液中的小示踪粒子的动态光散射来确定其在粒子尺度上的粘性和弹性模量。体尺度的粘弹性性质通过剪切流变学进行测量。示踪粒子在hmHEC中的运动在短时间内是扩散性的，而在中长时间内是次扩散性的。在未改性的HEC溶液的平行实验中未观察到长时间的次扩散运动，这可以用缔合网络中疏水改性聚合物链的受阻蠕动来解释。聚合物分子本身的动态光散射表明，由于大规模缔合网络结构，hmHEC中的链弛豫由缓慢的浓度依赖性过程主导，而HEC中的链弛豫由快速的浓度无关的类Rouse动力学主导。
