Song Hyeong Yong, Faust Lorenz, Son Jinha, Kim Mingeun, Park Seung Joon, Ahn Suk-Kyun, Wilhelm Manfred, Hyun Kyu
School of Chemical and Biomolecular Engineering, Pusan National University, Busan 46241, Korea.
Institute of Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraβe 18, 76131 Karlsruhe, Germany.
Polymers (Basel). 2020 Feb 7;12(2):365. doi: 10.3390/polym12020365.
：Linear and nonlinear rheological properties of model comb polystyrenes (PS) with loosely to densely grafted architectures were measured under small and medium amplitude oscillatory shear (SAOS and MAOS) flow. This comb PS set had the same length of backbone and branches but varied in the number of branches from 3 to 120 branches. Linear viscoelastic properties of the comb PS were compared with the hierarchical model predictions. The model underpredicted zero-shear viscosity and backbone plateau modulus of densely branched comb with 60 or 120 branches because the model does not include the effect of side chain crowding. First- and third-harmonic nonlinearities reflected the hierarchy in the relaxation motion of comb structures. Notably, the low-frequency plateau values of first-harmonic MAOS moduli scaled with Mw-2 (total molecular weight), reflecting dynamic tube dilution (DTD) by relaxed branches. Relative intrinsic nonlinearity exhibited the difference between comb and bottlebrush via no low-frequency peak of bottlebrush corresponding to backbone relaxation, which is probably related to the stretched backbone conformation in bottlebrush.
在中小振幅振荡剪切（SAOS和MAOS）流动条件下，测量了具有从松散到密集接枝结构的模型梳状聚苯乙烯（PS）的线性和非线性流变特性。该梳状PS系列具有相同长度的主链和支链，但支链数量从3到120个不等。将梳状PS的线性粘弹性特性与分层模型预测结果进行了比较。该模型对具有60或120个支链的密集支化梳状聚合物的零剪切粘度和主链平台模量预测偏低，因为该模型未考虑侧链拥挤效应。一次和三次谐波非线性反映了梳状结构松弛运动中的层级结构。值得注意的是，一次谐波MAOS模量的低频平台值与Mw-2（总分子量）成比例，反映了松弛支链引起的动态管稀释（DTD）。相对固有非线性通过不存在对应于主链松弛的低频峰表现出梳状聚合物和刷状聚合物之间的差异，这可能与刷状聚合物中伸展的主链构象有关。
