کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1522507 | 995311 | 2013 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: The effect of copper ions on interaction of UV radiation with methacrylic matrix – EPR study The effect of copper ions on interaction of UV radiation with methacrylic matrix – EPR study](/preview/png/1522507.png)
• The carboxyls in matrix of polymer increase the loading capacity of Cu ions.
• There is produced much more radicals in Methafilcon A with Cu ions than without them.
• The carboxyls coordinated with copper ions play a key role in UV-degradation process.
The role of metal ions introduced to polymer matrix in the photochemical degradation of material is not fully understood. In this paper, we considered the effect of copper ions on the photochemical changes in Methafilcon A after UV-irradiation. The presence of methacrylic acid in the structure of Methafilcon A increases the loading capacity of these ions. In result, there is observed the production much more radicals after UV-irradiation than in pure matrix, without copper ions. When the time of UV-exposure increases, the EPR signal of trapped Cu(II) ions in the material decreases. This proves the transformation of Cu(II) to a diamagnetic state of stable Cu(I)-intermediates or copper oxides. Simultaneously, in the first 5-min of UV-irradiation there is observed a rapid increase in intensity of the radical signal, which disappears when the exposure time is extended. This mechanism of radical generating is quite different than for Methafilcon A matrix without copper ions.
Journal: Materials Chemistry and Physics - Volume 143, Issue 1, 16 December 2013, Pages 440–445