Intrinsic Viscosity of Cyclic Polystyrene
Intrinsic Viscosity of Cyclic Polystyrene
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DOI：
10.1021/acs.macromol.7b01511
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发表时间：
2017-10-10
期刊：
影响因子：
5.5
通讯作者：
Roovers, Jacques
中科院分区：
文献类型：
--
作者：
Jeong, Youncheol;Jin, Ye;Roovers, Jacques
用体积排阻色谱-三重检测系统测定了分子量为16 ~ 370 K的环状聚苯乙烯（C-PS）和线性聚苯乙烯（L-PS）在THF中的特性粘数。采用阴离子聚合法合成了线型遥爪前驱体，通过闭环反应制备了C-PS样品。合成的C-PS样品在关环反应后含有各种副产物，在临界条件下用液相色谱法分离得到高纯度的C-PS。L-PS的特性粘数与文献值吻合较好，而C-PS的特性粘数明显低于文献值。C-PS的Mark-Houwink指数为0.67，略低于L-PS在良溶剂中的0.70。因此，在THF中C-PS与L-PS的特性粘度之比（g' = [η]（C）/[η]（L））不是与MW无关的，而是随着MW增加而降低（0.63 >= [η]（C）/[η]（L）>= 0.57）。特性粘数的变化趋势与计算机模拟结果吻合较好。[eta]（C）与文献值的差异主要归因于早期研究中线性副产物的污染。
The intrinsic viscosity of cyclic polystyrenes (C-PS) and linear polystyrenes (L-PS) with molecular weight (MW) ranging from 16K to 370K was measured in THF using size exclusion chromatography coupled with a triple detection system. The C-PS samples were prepared by a ring-closure reaction of telechelic linear precursor synthesized by anionic polymerization. As-synthesized C-PS samples after the ring closure reaction contain various byproducts, and they were fractionated by liquid chromatography at the critical condition to obtain highly pure C-PS. While the intrinsic viscosity of L-PS agrees well with the literature data, C-PS shows significantly lower value than the literature values. The Mark-Houwink exponent of C-PS is 0.67, somewhat lower than 0.70 for L-PS in the good solvent over the MW range examined. Therefore, the ratio of the intrinsic viscosity of C-PS to L-PS (g' = [eta](C)/[eta](L)) in THF is not MW independent but decreases as MW increases (0.63 >= [eta](C)/[eta](L) >= 0.57). The trend of intrinsic viscosity agrees well with the computer simulation result. The discrepancy in [eta](C) from the literature values can largely be attributed to the contamination of linear byproducts in the earlier studies.