Oxygen Plasma-Induced Conversion of Silver Complex Ink into Conductive Coatings
, Meijuan Cao 1,*, Ji Yang 1, Xiangjun Guo 1, Xinfeng Sun 2,*, Tao Wang 3,*, Yuansheng Qi 1, Luhai Li 1, Huabin Zeng 4 and Meng Sun 5Round 1
Reviewer 1 Report
Comments and Suggestions for Authors1. In the introduction Section, line number 24 addressing metallic inks should start with a short definition of metallic inks.
2. What is the extent of the adhesion strength of the coating?
3. Does the current coating oxidize?
4. Does the coating process affect the inherent mechanical properties of the substrate?
5. The image quality of Figure 6 must be improved.
Comments on the Quality of English LanguageNeed to be improved. Avoid big sentences
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors-Lots of work have been done on plasma based coating on plastic. Do a proper literature survey and discuss about different types of coating materials.
-Literature gap is missing.
-Discuss about the chemical and physical properties of the material.
-Add a flowchart of the experimental methodology.
-Mark out the defects in the micrographs and discuss them.
-Fig 1 and 6 should be clear and big. Choose brighter colours to define each things.
-Provide convergence of the results with previous research. How your developed coating is better?
-Re-write the conclusion stating important results. Add some numeric results.
-State the applicability of your developed coating.
-Add some future scope.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis manuscript describes the fabrication process of Ag NP film for conductive coating. In the manuscript, the author mentioned that AgNPs are fabricated from the AgNO3/PVA dried film, followed by O2 plasma treatment. This manuscript seems interesting and novel. However, from my understanding, there is concept misunderstanding. Also the manuscript lacks its scientific soundness. Therefore, this manuscript might not be considered to be published unless the authors can provide additional information to support their idea. My concerns and comments are listed below:
1. Typo issue: there are some words in the manuscript are separated into two parts by dash "-". Please review and correct the spelling.
2. In the introduction section, paragraph 1. Author cited the Dong et al develop silver MOD decomposed and gave resistivity value of 8.6 uohm*cm. Please clarify that at what dimension, the resistivity reaches 8.6 uohm*cm.
3. In the Materials and Methods, Section 2.2 Preparation of AgNO3-PVA and plasma process. Please clarify the plasma type. Is this a ICP or CCP? Is there any bias power? Any Ar gas to dilute the O2?
4. Also, please clarify the coating method in this section, instead of discussing the method in the following section. The author said the film is coated after the drying process. What is the drying temperature? How did the authors dry 90% water from the mixed solution at room temperature?
5. Section 3.2, XPS measurement: The author claimed that after plasma treatment, the intensity of C and O peak reduced. The author concluded that this is because the silver ion sink due to the huge mass of the Ag. I partially agree with this. I think it is more likely that AgNO3 condensed during the water drying process, or Ag NPs are already formed during the drying process. Did author test the Ag distribution in the coating film?
6. Authors conclude that O2 plasma treatment reduced Ag+ to Ag(0) based on the experimental results. However, under the O2 plasma, it is more likely that polymer PVA will be burnt. O2 plasma has more aggressive oxidation ability, instead of reduction. Therefore, probably, some byproducts from the burnt polymer help to reduce the Ag+ to the Ag. I am so confused about this conclusion and would not agree with this, unless the authors could provide more evidence to support their idea.
7. After the plasma treatment, will the AgNO3 fully reduced to the Ag(0)? What is the conversion rate?
8. Author could add a control experiment by treating AgNO3 powder with O2 plasma, and characterize the XPS of the treated Ag powder to see if O(1s) can be observed.
9. Section 3.4. Authors discussed the process of the Ag formation. First, the author claimed that the particles were distributed on the surface of the coating. However, from my understanding, this is because the polymer is burned by the O2 plasma and then Ag component is exposed. Second, authors claimed that with the prolongation of treatment time, Ag NPS polymerized and formed a silver network. However, from my understanding, it is because more Ag is exposed on the surface, which cause the particle aggregation.
10. Could author measure the thickness of the Ag film by either XRF or AFM? Also, could author calculate the resistivity (uohm*cm) at certain dimension?
Comments on the Quality of English LanguageThe English is good enough.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAll the revisions are ok.
Author Response
Thanks very much for taking the time to review this manuscript. We appreciate all your generous comments and suggestions!
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors well explained the most of my concerns from author's response. However, there are some issues that author failed to respond clearly. Please see my concern as below.
1. The author claimed that the Ag ions sinks during the drying process. However, after the O-plasma treatment, the AgNPs are exposed to the top surface of the film, which is abnormal. It is extremely hard for Ag+ or Ag cluster to move in the dried polymer film, considering the Einstein-Stokes Equation. How could Ag cluster/Ag+ move from the bottom to the top?
2. The author claimed that there is no PVA burning process during the O-plasma treatment. I apologize that I did not clarify the concept of "burning". From my knowledge and experience, polymer will be significantly etched under the O plasma, even though it is at room temperature. There are a lot of references/articles to support this. Therefore, the statement that the author mentioned the oxygen plasma is treating the surface of the polymer film at high plasma power (up to 500W) does not have soundness to me, unless the author could provide references to support.
3. Since the author claimed that the O2 plasma reacting with the organic matter, generating free electron, which reduced the Ag+. However, the author failed to provide the control experiment to test this (AgNO3 powder treated with O2 plasma).
Author Response
Dear reviewer,
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Oxygen plasma-induced conversion of silver complex ink into conductive coatings” (ID: coatings-2704372). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. According to your nice suggestions, we have made corrections to our previous draft, the detailed corrections are listed below.
Reviewer 3
General Comments and Suggestions:
The authors well explained the most of my concerns from author's response. However, there are some issues that author failed to respond clearly. Please see my concern as below.
- Comments and Suggestions: The author claimed that the Ag ions sinks during the drying process. However, after the O-plasma treatment, the Ag NPs are exposed to the top surface of the film, which is abnormal. It is extremely hard for Ag+ or Ag cluster to move in the dried polymer film, considering the Einstein-Stokes Equation. How could Ag cluster/Ag+ move from the bottom to the top?
Reply: We sincerely thank you for your valuable comments. After researching the literature and referring to your opinions, we finally believe that it may be due to the formation of coordination bonds between the hydroxyl groups on the PVA and Ag+, and the PVA "wraps" the silver ions. At the same time, XPS has a limited detection range, so no silver ions are detected.
- Comments and Suggestions: The author claimed that there is no PVA burning process during the O-plasma treatment. I apologize that I did not clarify the concept of "burning". From my knowledge and experience, polymer will be significantly etched under the O plasma, even though it is at room temperature. There are a lot of references/articles to support this. Therefore, the statement that the author mentioned the oxygen plasma is treating the surface of the polymer film at high plasma power (up to 500W) does not have soundness to me, unless the author could provide references to support.
Reply: We sincerely appreciate your valuable comments. We have reviewed the literature and we perceive that the previously proposed principle of silver ion reduction is uncomfortable. Combining the literature and experimental results, we believe that chemical etching of PVA occurred under oxygen plasma treatment. The reactive oxygen in the oxygen plasma reacted with the PVA, causing the PVA polymer chains to break down and be further oxidized. This decomposition resulted in the transfer of intramolecular electrons from ligands to metal ions, prompting the reduction of silver ions to Ag0.
- Comments and Suggestions: Since the author claimed that the O2 plasma reacting with the organic matter, generating free electron, which reduced the Ag+. However, the author failed to provide the control experiment to test this (AgNO3 powder treated with O2 plasma).
Reply: Your comments are sincerely appreciated. The controlled experiment helps to improve our paper and provide us with more solid data support. However, we are sorry that we were unable to supplement the experiment due to instrumentation as well as time issues. In order to make up for the shortcomings, we have reviewed more literature. We hope that the combination of previous experience and our experimental results can better support and improve our thesis.
We have done our best to improve the manuscript and have made some changes (marked in red) in the revised version that do not affect the content and framework of the paper. We would like to express our sincere gratitude to the reviewers for their enthusiastic work and hope that the revisions will be acknowledged. Thank you again for your comments and suggestions.
Yours sincerely,
