کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1431090 | 1509189 | 2008 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Structural transition of a homopolymer in solvents mixture Structural transition of a homopolymer in solvents mixture](/preview/png/1431090.png)
The present work is aimed at studying the thermodynamic behaviour of a polymer in solvents mixture. Dynamic light scattering is used to measure the hydrodynamic radius of polyvinylpyrrolidone (Mw = 360,000 g/mol), in water/methanol solvents mixture, versus the mixed solvents composition at 25 °C. Then, we show that the polymer conformation adopts the Coil–Globule–Coil structure when the methanol molar fraction XA is varied. This transition is attributed to solvent quality change which result from water and methanol complex formation. The polymer contraction rate calculated for each composition takes its maximum value at XA = 0.17. Hildebrand theory assuming the solvents mixture as an equivalent solvent was used to analyze the change in mixed solvents quality. These changes can be attributed to dispersive forces in solvents mixture.
Journal: Materials Science and Engineering: C - Volume 28, Issues 5–6, 1 July 2008, Pages 811–815