کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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229206 | 464863 | 2010 | 5 صفحه PDF | دانلود رایگان |
Thermally collapsed poly(vinylpyrrolidone) (PVP) polymer radicals preferably undergo intra-crosslinking reactions producing a nanogel structure rather than a macro-gel that would be caused by inter-crosslinking reactions. In the radiolysis of PVP aqueous solutions, the predominance of the intra-crosslinking reactions was achieved at elevated temperatures up to 77 °C. The dominance of intra-crosslinking under these conditions was confirmed by the molecular weight measurements using asymmetric field flow fractionation (AFFF). A higher yield of C-centered free radicals along the PVP chain at higher electron beam pulse repetition rate (300 Hz) enhances the intra-crosslinking reactions. This represents, mainly, the intra-crosslinking of the radicals of collapsed PVP molecules, along with a minor contribution of inter-crosslinking of the polymer dimers formed by transient occupation by two molecules in the same hydrodynamic volume and the increased diffusivity at the higher temperature.
Journal: Journal of Industrial and Engineering Chemistry - Volume 16, Issue 5, 25 September 2010, Pages 657–661