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Long-term aging of Ag/a-C:H:O nanocomposite coatings in air and in aqueous environment

View Article: PubMed Central - PubMed

ABSTRACT

Nanocomposite coatings of silver particles embedded in a plasma polymer matrix possess interesting properties depending on their microstructure. The film microstructure is affected among others also by the RF power supplied during the deposition, as shown by transmission electron microscopy. The optical properties are characterized by UV–vis–NIR spectroscopy. An anomalous optical absorption peak from the Ag nanoparticles is observed and related to the microstructure of the nanocomposite films. Furthermore, a long-term aging of the coatings is studied in-depth in ambient air and in aqueous environments. It is shown that the studied films are not entirely stable. The deposition conditions and the microstructure of the films affect the processes taking place during their aging in both environments.

No MeSH data available.


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UV–vis–NIR absorbance spectra of the Ag/a-C:H:O nanocomposite films deposited at the RF powers of 30 and 50 W (left) and 60 W (right). The spectra were measured right after the deposition, and after aging in air for 1 month and 22 months and in water for 1 day. The optical spectrum of the glass substrate is displayed for comparison.
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Figure 8: UV–vis–NIR absorbance spectra of the Ag/a-C:H:O nanocomposite films deposited at the RF powers of 30 and 50 W (left) and 60 W (right). The spectra were measured right after the deposition, and after aging in air for 1 month and 22 months and in water for 1 day. The optical spectrum of the glass substrate is displayed for comparison.

Mentions: The aging of the Ag/a-C:H:O nanocomposite films in air or in water induces changes in their optical spectra as can be seen in figure 8. The dominant feature in the spectra of the aging films is the decrease in the intensity of the absorbance peak which is especially striking in the case of aging in water. This decrease is caused by the loss of silver material. However, an interesting effect can be observed in the NIR part of the spectrum of the film deposited at 50 W. While the values of absorbance of the films both with low (30–45 W) and high (60 W) filling factors decrease in this region during aging, the absorbance of the film deposited at 50 W increases. The exact cause of this effect is not known, but it might be connected with the special percolated structure of this film and the leaching of Ag+ ions as was discussed above. It can be expected that not all of the ions released from the silver nanoparticles also leave the matrix. They might remain (temporarily) bound within the plasma polymer and affect the permittivity of the matrix or virtually increase the percolation of the film. Since these are only distributed ions they could not be detected in the TEM characterization. Further, the positions of the SPR slightly red-shift during aging, even though, the shape factors of the films with higher filling factors increase. The maximum in the spectrum of the 60 W film aged in water cannot be identified. Finally, the FWHM measures of the SPR peaks increase during aging. Overall, the trends of the changes are the same during aging in air or in water. However, it can be seen that their progress is much faster and more pronounced during their aging in water. This observation corresponds to the observed changes in the microstructure of the nanocomposites.


Long-term aging of Ag/a-C:H:O nanocomposite coatings in air and in aqueous environment
UV–vis–NIR absorbance spectra of the Ag/a-C:H:O nanocomposite films deposited at the RF powers of 30 and 50 W (left) and 60 W (right). The spectra were measured right after the deposition, and after aging in air for 1 month and 22 months and in water for 1 day. The optical spectrum of the glass substrate is displayed for comparison.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036476&req=5

Figure 8: UV–vis–NIR absorbance spectra of the Ag/a-C:H:O nanocomposite films deposited at the RF powers of 30 and 50 W (left) and 60 W (right). The spectra were measured right after the deposition, and after aging in air for 1 month and 22 months and in water for 1 day. The optical spectrum of the glass substrate is displayed for comparison.
Mentions: The aging of the Ag/a-C:H:O nanocomposite films in air or in water induces changes in their optical spectra as can be seen in figure 8. The dominant feature in the spectra of the aging films is the decrease in the intensity of the absorbance peak which is especially striking in the case of aging in water. This decrease is caused by the loss of silver material. However, an interesting effect can be observed in the NIR part of the spectrum of the film deposited at 50 W. While the values of absorbance of the films both with low (30–45 W) and high (60 W) filling factors decrease in this region during aging, the absorbance of the film deposited at 50 W increases. The exact cause of this effect is not known, but it might be connected with the special percolated structure of this film and the leaching of Ag+ ions as was discussed above. It can be expected that not all of the ions released from the silver nanoparticles also leave the matrix. They might remain (temporarily) bound within the plasma polymer and affect the permittivity of the matrix or virtually increase the percolation of the film. Since these are only distributed ions they could not be detected in the TEM characterization. Further, the positions of the SPR slightly red-shift during aging, even though, the shape factors of the films with higher filling factors increase. The maximum in the spectrum of the 60 W film aged in water cannot be identified. Finally, the FWHM measures of the SPR peaks increase during aging. Overall, the trends of the changes are the same during aging in air or in water. However, it can be seen that their progress is much faster and more pronounced during their aging in water. This observation corresponds to the observed changes in the microstructure of the nanocomposites.

View Article: PubMed Central - PubMed

ABSTRACT

Nanocomposite coatings of silver particles embedded in a plasma polymer matrix possess interesting properties depending on their microstructure. The film microstructure is affected among others also by the RF power supplied during the deposition, as shown by transmission electron microscopy. The optical properties are characterized by UV–vis–NIR spectroscopy. An anomalous optical absorption peak from the Ag nanoparticles is observed and related to the microstructure of the nanocomposite films. Furthermore, a long-term aging of the coatings is studied in-depth in ambient air and in aqueous environments. It is shown that the studied films are not entirely stable. The deposition conditions and the microstructure of the films affect the processes taking place during their aging in both environments.

No MeSH data available.


Related in: MedlinePlus