论文标题
微结构对聚乙二醇溶液中聚合物链动力学的影响
Effect of microstructure on polymer chain dynamics in polyethylene glycol solutions
论文作者
论文摘要
微观结构和相互作用对水中聚乙烯乙二醇（PEG）溶液中分段动力学的影响，用宏观振荡性流变学和荧光探针的微尺度扩散进行探测。 PEG溶液荧光回收（FRAP）曲线的固定分数随着PEG浓度的增加而增加，对于PEG体积分数（C）> 0.2，表明结构化。 PEG解决方案微尺度扩散系数遵循C <0.8的Rouse缩放D {\ Alpha} C^（-0.54），类似于良好溶剂中未进入的中性聚合物。使用异质动力学，在PEG矩阵中添加纳米粘土膨润土（B）减慢了3-7次的探针扩散。通过在PEG基质中添加羧甲基纤维素（CMC），探针扩散是均匀的，在扩散时间中的增强量较小。用于PEG，PEG + B和PEG + CMC溶液的宏观存储模量作为粘性流体状，然后是短弹性高原。除了弹性高原之外，缩放率是浓度依赖性的功率定律，大于0.1 <c <0.2 PEG溶液的Rouse缩放率。我们确定了由于PEG中分子间相互作用而引起的时间尺度τ_b，因此，对于ω>τ_b^（-1），恢复了Rouse缩放。将CMC添加到PEG中还恢复了Rouse缩放。 B的添加提供了来自聚合物矩阵和B颗粒网络的贡献，从而偏离了纯鲁斯行为。静态微观结构研究揭示了由于增加PEG基质中粘土颗粒浓度的耗尽相互作用而引起的粘土聚集，这导致储存模量与C的非单向浓度依赖性。
Effect of microstructures and interactions on segmental dynamics in polyethylene glycol (PEG) solution in water is probed with macro-scale oscillatory rheology and micro-scale diffusion of a fluorescent probe. PEG solution fluorescence recovery after photobleaching (FRAP) curves have immobile fractions which increase with PEG concentration, for PEG volume fraction (c) > 0.2, indicating structuring. PEG solution micro-scale diffusion coefficients follow Rouse scaling D {\ alpha} c^(-0.54) for c < 0.8, resembling unentangled neutral polymers in good solvent. Addition of nanoclay bentonite (B) in PEG matrix slows down probe diffusion 3-7 times, with heterogeneous dynamics. With addition of carboxymethyl cellulose (CMC) in PEG matrix, probe diffusion is homogeneous with negligibly small enhancement in diffusion time. The macroscale storage modulii for PEG, PEG+B, and PEG + CMC solutions scale as viscous fluid-like, followed by short elastic plateau. Beyond the elastic plateau, the scaling is a concentration-dependent power law greater than the Rouse scaling of 0.5 for 0.1<c<0.2 PEG solutions. We identify a time scale τ_b due to intermolecular interactions in PEG, such that for ω>τ_b^(-1) , Rouse scaling is recovered. Addition of CMC to PEG also restores Rouse scaling. Addition of B gives contributions from both polymer matrix and network of B particles, leading to departure from pure Rouse behaviour. Static microstructural studies reveal clay aggregation due to depletion interactions on increasing the concentration of clay particles in PEG matrix, which leads to a non-monotonic concentration dependence of storage modulus with c.
