کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5188539 | 1381158 | 2007 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
A molecular dynamics study of short-chain ordering in crystalline LiPF6·PEO6
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Molecular dynamics (MD) simulations have been made of the crystalline short-chain LiPF6·PEO6 system to probe structural ordering for different chain-end arrangements for a methyl-terminated monodisperse poly(ethylene oxide) (EO23Mw = 1059) host polymer. Five different start structures have been studied, two “smectic” and three “nematic”, to represent different types of relative alignment of the end-groups between adjacent PEO chains, and different chain-end coordination situations to the Li-ions. One particular situation is found to result effectively in Li-ion bridging between PEO chains along the chain axes, thereby creating continuous ion transport pathways across the chain breaks. This situation is also found to give rise to Li+-PF6â ion-pairing and Li-O coordination instabilities in the end-group regions, where coordination to Li-ions would appear to have a more radical influence on local structure than the issue of smectic vs. nematic end-group alignment. It could be that such structural situations involving bridging Li-ions (in both smectic and nematic arrangements) are a necessary condition for the promotion of Li-ion transport in the chain direction. Comparison of simulated and experimental XRD profiles is concluded to be an inappropriately crude and uncertain technique for distinguishing between possible short-chain ordering models.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 48, Issue 21, 5 October 2007, Pages 6448-6456
Journal: Polymer - Volume 48, Issue 21, 5 October 2007, Pages 6448-6456
نویسندگان
A. Liivat, D. Brandell, A. Aabloo, J.O. Thomas,