کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5188430 | 1381155 | 2006 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Dynamics of thermoresponsive PNIPAM-g-PEO copolymer chains in semi-dilute solution
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The effects of concentration and temperature on dynamics of poly(N-isopropylacrylamide)-graft-poly(ethylene oxide) (PNIPAM-g-PEO) chains in semi-dilute aqueous solution were studied by static and dynamic laser light scattering. The intensity-intensity time correlation function shows a fast and a slow relaxation mode, with line widths Îf and Îs, respectively. Îf is scaled to the scattering vector (q) as Îf â q2, revealing that it is due to the cooperative diffusion of the subchains between two neighboring entangled points. As the concentration increases, the slow relaxation becomes slower and contributes more to the total scattered light intensity, indicating that the slow relaxation is related to the chain entanglement. On the other hand, when the solution temperature increases, the PNIPAM chain backbone shrinks, but the fast relaxation remains and the slow mode slows down with a minimum rate at â¼33 °C. It indicates that the slow mode arises from inter-chain clustering, which is gradually suppressed by the intra-chain shrinking. The sample position independence of the time-averaged scattered light intensity ãIãT reveals that the solution is homogeneous and the clustering is transient.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 47, Issue 25, 22 November 2006, Pages 8367-8373
Journal: Polymer - Volume 47, Issue 25, 22 November 2006, Pages 8367-8373
نویسندگان
Hongwei Chen, Xiaodong Ye, Guangzhao Zhang, Qijin Zhang,