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Wormlike micelles versus water-soluble polymers as rheology-modifiers: similarities and differences
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2017-09-04 00:00:00 , DOI: 10.1039/c7cp04962e Ji Wang 1, 2, 3, 4, 5 , Yujun Feng 1, 2, 3, 4, 6 , Niti R. Agrawal 7, 8, 9, 10 , Srinivasa R. Raghavan 7, 8, 9, 10
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2017-09-04 00:00:00 , DOI: 10.1039/c7cp04962e Ji Wang 1, 2, 3, 4, 5 , Yujun Feng 1, 2, 3, 4, 6 , Niti R. Agrawal 7, 8, 9, 10 , Srinivasa R. Raghavan 7, 8, 9, 10
Affiliation
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Wormlike micelles (WLMs) formed from surfactants have attracted much attention for their ability to thicken water in a manner similar to water-soluble polymers. It is known that WLMs are cylindrical filaments that can attain very long contour lengths (∼few μm), akin to chains of polymers with ultra-high molecular weights (UHMWs). In this study, we aim to make a direct comparison between the thickening capabilities of WLMs and UHMW polymers. The chosen surfactant is erucyl dimethyl amidopropyl betaine (EDAB), a C22-tailed zwitterionic surfactant known to form particularly long WLMs independent of salt. The chosen polymer is nonionic polyacrylamide (PAM) having an UHMW of 12 MDa. Both EDAB WLMs and the PAM show strong thickening capability in saline water at 25 °C, but the WLMs are more efficient. For example, a 1.0 wt% EDAB WLM sample has a similar zero-shear viscosity η0 (∼40
000 mPa s) to a 2.5 wt% PAM solution. When temperature is increased, both samples show an exponential reduction in viscosity, but the WLMs are more sensitive to temperature. Microstructural differences between the two systems are confirmed by data from small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). As expected, the key differences are that the WLM chains have a larger core radius (Rcore) and in turn, a longer persistence length (lp) than the PAM chains.
中文翻译：
蠕虫状胶束与水溶性聚合物作为流变改性剂的异同
由表面活性剂形成的蠕虫状胶束（WLM）以类似于水溶性聚合物的方式增稠水的能力引起了人们的广泛关注。众所周知，WLM是圆柱形长丝，可以达到非常长的轮廓长度（约几微米），类似于具有超高分子量（UHMW）的聚合物链。在这项研究中，我们旨在直接比较WLM和UHMW聚合物的增稠能力。选择的表面活性剂是芥酸二甲基酰胺基丙基甜菜碱（EDAB），C 22的两性离子表面活性剂，已知可形成特别长的WLM，与盐无关。所选的聚合物是UHMW为12 MDa的非离子聚丙烯酰胺（PAM）。EDAB WLM和PAM在25°C的盐水中均显示出强大的增稠能力，但WLM的效率更高。例如，1.0重量％的EDAB WLM样品具有类似的零剪切粘度η 0（〜40000 mPa s）至2.5 wt％PAM溶液。当温度升高时，两个样品的粘度均呈指数下降，但WLM对温度更敏感。小角中子散射（SANS）和低温透射电子显微镜（cryo-TEM）的数据证实了这两种系统之间的微观结构差异。不出所料，主要区别在于WLM链的核心半径（R core）比PAM链大，而持久长度（l p）更长。
更新日期：2017-09-20
000 mPa s) to a 2.5 wt% PAM solution. When temperature is increased, both samples show an exponential reduction in viscosity, but the WLMs are more sensitive to temperature. Microstructural differences between the two systems are confirmed by data from small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). As expected, the key differences are that the WLM chains have a larger core radius (Rcore) and in turn, a longer persistence length (lp) than the PAM chains.
中文翻译：
蠕虫状胶束与水溶性聚合物作为流变改性剂的异同
由表面活性剂形成的蠕虫状胶束（WLM）以类似于水溶性聚合物的方式增稠水的能力引起了人们的广泛关注。众所周知，WLM是圆柱形长丝，可以达到非常长的轮廓长度（约几微米），类似于具有超高分子量（UHMW）的聚合物链。在这项研究中，我们旨在直接比较WLM和UHMW聚合物的增稠能力。选择的表面活性剂是芥酸二甲基酰胺基丙基甜菜碱（EDAB），C 22的两性离子表面活性剂，已知可形成特别长的WLM，与盐无关。所选的聚合物是UHMW为12 MDa的非离子聚丙烯酰胺（PAM）。EDAB WLM和PAM在25°C的盐水中均显示出强大的增稠能力，但WLM的效率更高。例如，1.0重量％的EDAB WLM样品具有类似的零剪切粘度η 0（〜40
000 mPa s）至2.5 wt％PAM溶液。当温度升高时，两个样品的粘度均呈指数下降，但WLM对温度更敏感。小角中子散射（SANS）和低温透射电子显微镜（cryo-TEM）的数据证实了这两种系统之间的微观结构差异。不出所料，主要区别在于WLM链的核心半径（R core）比PAM链大，而持久长度（l p）更长。
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