Preparation and Performance Study of Carboxy-Functionalized Graphene Oxide Composite Polyaniline Modified Water-Based Epoxy Zinc-Rich Coatings
Round 1
Reviewer 1 Report
In this study, carboxy-functionalized graphene oxide/polyaniline (CGO/PANI) composites with a lamellar structure were prepared by in situ polymerization. The lamellar layer was used to form a labyrinthine structure in the coating to effectively retard the penetration of corrosive media, and the conductivity and unique anti-corrosion mechanism of polyaniline was used to further improve the anticorrosion performance of the coating. The work is interesting and the topic as well, but the presentation must be improved. Also, the interpretation of the performed experiments should be improved. The corrosion description should be compare to other carbon containing anticorrosion coatings - I. Kratochvílová, et al. : Zr alloy protection against high-temperature oxidation: coating by a double-layered structure with active and passive functional properties, Corrosion Science 163 (2020) 108270(1)-108270(11).
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Review to the article: Preparation and Performance Study of Carboxy-functionalized Graphene Oxide Composite Polyaniline Modified Water-based Epoxy Zinc-rich Coating.
Abstract
Graphene Oxide, what it is? Chemically it is not clear graphene is carbon, carbon oxide, carbon dioxide which are the gases? Please clarify real chemical name.
21. X-ray diffraction spectroscopy (XRD), a.
It is not a spectroscopy, it is just the method X-ray Diffraction.
Line 22 the improvement of the corrosion resistance of the prepared composites on the epoxy zinc-rich coatings was evaluated.
Probably you investigate the corrosion of the metallic substrate and did not corrosion of the coating.
25. aniline was successfully polymerized in situ on carboxy-functionalized graphene oxide, an…
It is better to replace polymerised to grafted to the surface of the graphene.
In the abstract no any information and even words about zinc flakes. How Zn interacts with PANI?
Line 175 Please define glycury electrode, what it is ?
I cannot approve any d.c. polarization curves measurements. For polymer coated metallic substrates this technique is never used. Reject Figure 6 and Table 1 and all discussion concerning OCP and dc polarization data. The main contribution is ohmic resistive drop in the coating. It is main inhibiting effect that decrease the current for 5-6 orders. Thus, you can not find any other effects due to masking by the ohmic resistance. The corrosion peoples never used this technique for polymeric coatings. If you saw that, it is wrong data.
OCP shifts by Zn in cathodic direction and PANI in anodic direction. Better to negative that can lead to cathodic protection of steel. Do not discuss OCP (voltameter measurement), nobody use OCP for coated metals. Normally SKP is used. Protection by PANI is not ensdetermined yet.
Conclusions
Please Remove the line 430.
The theoretical annual corrosion rate is reduced to 1.5589×10−7 mm/year, which is only 0.185 431 times that of pure W-B EZRCD.
It is wrong, you cannot measure the corrosion rate, only mass lost can be used after removing the coating.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
To be published in this form.
Reviewer 2 Report
Dear authors, thank you for understanding and correcting (removing Figure 6). Just one point. About definitions: polymerization and grafting. Polymerization is like in epoxy resin, two substances create one phase with uniform chemistry inside. Grafting is attaching the molecules to the surface, two-phase are existing with the gradient in chemical composition. So decide what you have, and how to write in your article.
kind regards
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
This paper by Chen et al. prepared carboxy-functionalized graphene oxide/polyaniline-epoxy zinc-rich coatings composite material. As prepared CGO/PANI/W-B EZRC material was systematically tested for the anticorrosion properties. Even though work is done in an orderly, lack of materials characterization and corrosion resistance insufficient explanations. I recommend major revision.
- Keep space between value and units, e.g page 3, 20mg, 40mg, 60mg, 80mg and 124 100mg.
- Page 4 and 5, section 3.1. Explain the detailed structure of SEM images like the PANI rod's width and length size. Before and after PANI coating (lamellae thickness) on CGO and CGO-PANI-3 in detail.
- Section 3.3. Figure 3(d) as the author claimed carboxyl functionalized CGO-PANI-3, carbonyl, and hydroxyl peaks do not appear. The author should account for this issue.
- In Figure 4, the author should arrange the XRD pattern in the order of GO, CGO, PANI, and CGO-PANI-3 for the reader’s better understanding.
- Page 10 and 11 annual corrosion rate equation and symbol abbreviations are mismatching.
- Explain the reason for CGO/PANI-3/W-B EZRC best anti-corrosion coating in detail in section 3.5.2.
Author Response
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Author Response File: Author Response.docx
Reviewer 2 Report
Chen et al. prepared Carboxy-functionalized Graphene Oxide Composite Polyaniline Modified Water-based Epoxy Zinc-rich Coatings. The manuscript presented well however many major concerns need to resolve before publication.
Line 12 -13, First sentence need to be rewritten. The sentence should not start with ‘it’.
Abstract need to be written be quantatively.
All the figures clarity need to be enhance.
Line 89, authors itself written it is schematic diagram, therefore please change it into scheme 1.
Line 95, FI-RT, it is FTIR. Check it.
There are many spelling errors in the manuscript Please check carefully throughout the manuscript.
Line 104, 2.1 materials spelling error. Correct it.
Section 2.5.1 characterization condition and instrument details need to provide.
Line 169, there should be space between 3.5 and wt%.
Line 174-179, this section need to be rewritten in better way and clearly.
In fig. 2, scale bar is not visible please mark it clearly. Same foe Fig. 5. Scale bar draw by yourself in dark mode. Please follow and cite this paper in text accordingly International journal of Biological Macromolecules 171 (2021) 457-464.
Please cite the recent references in each section of the results and discussion. Insert the following papers in the text accordingly Carbon 175, 534-575, https://doi.org/10.1155/2021/4933450, https://doi.org/10.1016/j.synthmet.2017.03.005, Cellulose, 29 (2022) 2399-2411. https://doi.org/10.1039/C3TA13462H and Journal of Industrial and Engineering Chemistry 21, 11-25,
In all figures please correct x- and y-axis caption. Example in fig 3, Wavenumber/cm-1 please write wavenumber (cm-1). Same goes for all figures in both x-and y axis.
Authors should calculate the crystallinity of all sample in fig 4 and include its related discussion in section 3.3. Please cite the following paper in text accordingly, Journal of Luminoscense, 228 (2020) 117593, International journal of Biological Macromolecules 171 (2021) 457-464, and Journal of the Taiwan Institute of Chemical Engineers 2022 (134) 104301.
Line 296-302, need to rewritten in the better way.
Fig 6 and fig 7 clarity very very low. Seems invisible in PDF file. Please improve its clarity.
Please compare the previous study related to your study in the section 3.6.
Section 4 should be conclusions.
Conclusion section seems very poor written. Please improve it with interesting results for this study.
Reference style is wrong as per the journal guidelines. Please correct all reference style. Coating journal need Journal abbreviation. Check reference no 30.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Line 98: the condition that was used for conducting the polarization test has not been mentioned. ( the electrolyte used for test, potential range, potential sweep (scan)rate, the exposed area of the specimen). More standard details of the EIS and polarization tests should be presented.
Line 126: why these ratios (1% to 5%) has been chosen?
Line 141: the word “after the thickener is fully dissolved” has been repeated.
Line 154: it is recommended to report the properties of Go/PANI coatings with similar ratios to CGo/PANI coating as the blank controls.
Line 299: Use SEM micrographs to validate the claim of agglomeration of the lamellae.
Line 170: Use potentiodynamic polarization curves instead of dynamic potential polarization and Potential polarization curves throughout the manuscript.
In table 1 and in Fig 7 and lines 317 and 315: Upper case 'I' is used for current density while it indicates current not current density. In corrosion science, we use i (lower case) to indicate the current density.
Line 314: The formula used should be referred to an appropriate reference that deals with zinc-rich paints. The main question is about the terms of the formula. As mentioned in Line 316, M indicates the molecular weight of iron while in the system used in the current study the corrosion of Zinc occurs beside the corrosion of the substrate. I am not sure that we can use this formula to determine the corrosion rate of zinc-rich painted substrates.
Line 351: the condition that the salt spray test has been conducted and the relevant standard should be explained in the materials and method section.
Line 358: which gas is generated through the corrosion process? It is better to add images of the specimens before replacing them in the chamber or before conducting the test for more comparison.
Why the corrosion performance of the coating containing agglomerated CGO is better than the control specimens?
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors clarified all my queries in the revised version, which can be considered in Coatings.
Author Response
Thank you for your recognition of our work.
Reviewer 2 Report
Authors have not addressed all the comments as per my suggestions. Authors just correct minor errors. This manuscript needs again major revision prior to final publication in the Coatings journal.
Line 312, remove dot mark from wt.%.
Line 256-258, how authors know more crystallinity, it’s your findings need to calculate as per my previous suggestions.
Line 256-268, authors claim authors did not crystalize how authors prove it did authors do any expt. Please insert references.
Line 130. ml should be written as mL. Please check carefully all errors throughout the manuscript
Line 133, there should be sapped between 50 and oC. Please check carefully all errors throughout the manuscript. Line 141 also.
Line 143, what is ‘-‘ Check it.
Check table 1 format. Not right.
Line 90-93. Line 81-85, needs references.
Scheme 1 caption needs to provide a better way.
There are still no references in the results and discussion section. The Authors have not cited any paper, which are suggested by the reviewer however authors answer all are cited it in the manuscript. Only FTIR part have references and XRD part only one. Insert
Authors do not follow journal guidelines. The references style is totally wrong. However, in response writing did very well. Coatings journal needs journal abbreviation. Here reviewer gives the reference style please follow it strictly. Check previously published papers in this journal.
ï‚· Journal Articles:
1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
ï‚· Books and Book Chapters:
2. Author 1, A.; Author 2, B. Book Title, 3rd ed.; Publisher: Publisher Location, Country, Year; pp. 154–196.
3. Author 1, A.; Author 2, B. Title of the chapter. In Book Title, 2nd ed.; Editor 1, A., Editor 2, B., Eds.; Publisher: Publisher Location, Country, Year; Volume 3, pp. 154–196.
What is 32 reference. Correct it.
Ref. no 38 GO-Ti3C2, check subscript carefully.
Author Response
Response to Reviewer 2 Comments
Point 1: Line 312, remove dot mark from wt.%.
Response 1: Thank you for your suggestion. I have checked the full text and changed it.
Point 2: Line 256-258, how authors know more crystallinity, it’s your findings need to calculate as per my previous suggestions.
Response 2: Thank you for your suggestion. We have carefully considered your comments. We feel that we cannot simply tell that CGO has a higher crystallinity by the sharper crystalline peaks of CGO. Therefore, we have removed the talk about crystallinity. Based on the formula of crystalline spacing, we calculated the layer spacing of both and gave the appropriate discussion.
Point 3: Line 256-268, authors claim authors did not crystalize how authors prove it did authors do any expt. Please insert references.
Response 3: Thank you for your suggestion. We have removed the reference to crystallinity. We have derived the crystalline spacing of 0.88 nm for GO and 0.90 nm for CGO based on the formula for crystalline spacing. the reason is due to mutual repulsion of carboxyl groups on the lamellae and cited the relevant literature.
Point 4: Line 130. ml should be written as mL. Please check carefully all errors throughout the manuscript
Response 4: Thank you for your suggestion. I have checked the full text and changed it.
Point 5: Line 133, there should be sapped between 50 and oC. Please check carefully all errors throughout the manuscript. Line 141 also.
Response 5: Thank you for your suggestion. I have checked the full text and changed it.
Point 6: Line 143, what is ‘-‘ Check it.
Response 6: Thank you for your suggestion. I have removed the '-'.
Point 7: Check table 1 format. Not right.
Response 7: Thank you for your suggestion. I have changed the format to the correct
Point 8: Line 90-93. Line 81-85, needs references.
Response 8: Thank you for your suggestion. I have inserted the appropriate references.
Point 9: Scheme 1 caption needs to provide a better way.
Response 9: Thank you for your suggestion. I have changed the original title ‘preparation flow chart’ to ‘Schematic diagram of CGO/PANI preparation process and anti-corrosion mechanism’.
Point 10: There are still no references in the results and discussion section. The Authors have not cited any paper, which are suggested by the reviewer however authors answer all are cited it in the manuscript. Only FTIR part have references and XRD part only one. Insert
Response 10: Thank you for your suggestion. I have introduced 6 references in the XRD section. Among them are the 2 you recommended.
Point 11: Authors do not follow journal guidelines. The references style is totally wrong. However, in response writing did very well. Coatings journal needs journal abbreviation. Here reviewer gives the reference style please follow it strictly. Check previously published papers in this journal.
Response 11: Thank you for your suggestion. I have corrected it to the correct format.
- Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.
Point 12: What is 32 reference. Correct it.
Response 12: Thank you for your suggestion. I have corrected it to the correct format.
Point 13: Ref. no 38 GO-Ti3C2, check subscript carefully.
Response 13: Thank you for your suggestion. I have subscripted the numbers
Reviewer 3 Report
Point 1. Abstract: line 24-26; Authors have claimed that carboxy-functionalized graphene oxide and the modified coating had significantly improved anticorrosive properties, where the best anticorrosive improvement was achieved when CGO: PANI=0.03.
Point 2. The effect of modifying treatment on the coating properties can only be assessed through investigating the properties of Go/PANI coatings with similar ratios to CGo/PANI coating as the blank controls. Your claim is not acceptable without evidence.
Point 3. Comment: the term “potentiodynamic polarization curves test” is wrong. We conduct potentiodynamic polarization tests to obtain polarization (potentiodynamic) curves.
Point 4. Comments: The report note doesn’t address the changes that have been done according to the previous comments. I have to search for the changes. This is not a regular manner to reply the reviewer’s comments
Point 5. Line 187: speed was 1 Mv/s????? we do not have such a big potential scan rate.
Point 6. In Fig.1 the letters a to e are not mentioned. Scale bars are hardly visible.
Point 7. In the Vertical axes title of Fig 6; the upper case 'I' is used for current density while it indicates current not current density.
Point 8. Line 368: As mentioned before, M indicates the molecular weight of iron while in the system used in the current study the corrosion of Zinc occurs beside the corrosion of the substrate. I am not convinced that we can use this formula to determine the corrosion rate of zinc-rich painted substrates. We use zinc to protect the substrate and decrease the corrosion rate of the substrate so how we can use the molecular weight of iron to calculate the rate of corrosion. Decreasing the corrosion rate of the substrate is the result of the sacrificial action of zinc.
Point 9. Why the corrosion performance of the coating containing agglomerated CGO is better than the control, CGO/PANI-1/W-B EZRC, and PANI/W-B EZRC coatings?
Author Response
Response to Reviewer 3 Comments
Point 1:. Abstract: line 24-26; Authors have claimed that carboxy-functionalized graphene oxide and the modified coating had significantly improved anticorrosive properties, where the best anticorrosive improvement was achieved when CGO: PANI=0.03.
Response 1: Thank you.
Point 2: The effect of modifying treatment on the coating properties can only be assessed through investigating the properties of Go/PANI coatings with similar ratios to CGo/PANI coating as the blank controls. Your claim is not acceptable without evidence.
Response 2: Thank you for your advice. I am very sorry for not considering this issue. As we mentioned in our analysis and conclusions, our work is more focused on the study of CGO/PANI composite ratio and the effect of CGO/PANI on the corrosion improvement of the coating. We hope to get better corrosion improvement by changing the structure of PANI (rod structure to sheet structure). This is the focus of our paper. Therefore, we set the control group as pure PANI and pure epoxy-rich zinc coating. Thank you for your understanding.
Point 3: Comment: the term “potentiodynamic polarization curves test” is wrong. We conduct potentiodynamic polarization tests to obtain polarization (potentiodynamic) curves.
Response 3: Thank you for your correction. I have checked the full text and corrected it.
Point 4: Comments: The report note doesn’t address the changes that have been done according to the previous comments. I have to search for the changes. This is not a regular manner to reply the reviewer’s comments.
Response 4: Sorry, that was my mistake. I will point out the specific changes I made later in the revision report.
Point 5: Line 187: speed was 1 Mv/s????? we do not have such a big potential scan rate.
Response 5: Thank you for your suggestion. We have changed '1Mv/s' to '1mV/s'. '1mV/s' is the correct experimental condition.
Point 6: In Fig.1 the letters a to e are not mentioned. Scale bars are hardly visible.
Response 6: Sorry, this was an oversight on our part. We have labeled the images as well as cited the numbers in the analysis. I don't know what the reason is. On my side it looks like the scale is clear.
If there are still questions, please let me know specifically.
Point 7: In the Vertical axes title of Fig 6; the upper case 'I' is used for current density while it indicates current not current density.
Response 7: Thank you for your advice. I have changed the vertical coordinate units to 'i'
Point 8: Line 368: As mentioned before, M indicates the molecular weight of iron while in the system used in the current study the corrosion of Zinc occurs beside the corrosion of the substrate. I am not convinced that we can use this formula to determine the corrosion rate of zinc-rich painted substrates. We use zinc to protect the substrate and decrease the corrosion rate of the substrate so how we can use the molecular weight of iron to calculate the rate of corrosion. Decreasing the corrosion rate of the substrate is the result of the sacrificial action of zinc.
Response 8: Thank you for your suggestion, I have replaced the formula. The article cited also uses this formula to study epoxy-rich zinc coatings(https://doi.org/10.1016/j.jhazmat.2021.126048). In addition, we believe that zinc is less susceptible to corrosion as it produces a dense oxide film on the surface under natural conditions. Corrosion of iron occurs when the corrosive medium reaches the steel substrate. The 'sacrificial organism' of zinc particles occurs passively. If we use the relative atomic mass of zinc instead of the relative atomic mass of iron, we can reach the same conclusion. Finally, the conclusion is consistent with the experimental data in the other sections, so we believe that this formula is applicable.
Point 9: Line 351: the condition that the salt spray test has been conducted and the relevant standard should be explained in the materials and method section.
Response 9: Thank you for your suggestion. It was an oversight on our part. It has been corrected.
Point 10: Why the corrosion performance of the coating containing agglomerated CGO is better than the control, CGO/PANI-1/W-B EZRC, and PANI/W-B EZRC coatings?
Response 11: This is our point: as the percentage of CGO increases, it is clear that PANI can no longer be fully loaded against CGO. So the unloaded lamellae will agglomerate during the drying process. This is the reason for the large surface energy of graphene. But this agglomeration is only a partial agglomeration and still can perform partially, so it is better than the unmodified coating in terms of corrosion resistance. From the salt spray resistance graph, the coating corrosion resistance of CGO/PANI-5 (g) with agglomeration phenomenon is not better than CGO/PANI-1/W-B EZRC (c), but only better than PANI/W-B EZRC (b) and pure epoxy zinc-rich coating (a).
Round 3
Reviewer 2 Report
The authors improved the manuscript. It can be published now.
Reviewer 3 Report
The effect of modifying treatment on the coating properties can only be assessed through investigating the properties of Go/PANI coatings with similar ratios to CGo/PANI coating as the blank controls. Your claim is not acceptable without evidence.
