Polyacrylate Latex Coating Binders Comprising Polypyrrole Component Prepared with “One-Pot” Synthesis

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

The manuscript was revised several times and I consider that the authors took the reviewers' comments into account.

Author Response

Dear reviewer,
Thank you for your subjective comments on our publication. 

Karolína Boštíková

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This work reports the synthesis of synthetic latices of polyacrylate and polypyrrole by “one-pot” strategy. The effect of polypyrrole content on the physico-mechanical properties and chemical resistance of the composite coatings was investigated. The anti-corrosion on the corrosion resistance of composite coatings with different pigments were also evaluated. The study is interesting and well organized.

I just have some minor comments.

1. For Fig.4, it’s good to also show the morphology pictures by SEM.

2. For Fig.5, it’s good to add SEM pictures at different magnifications showing the upper and lower surfaces of the coatings.

3. There is no morphology examination of the composite coatings with different pigments. Please add the SEM pictures of surfaces and fractures.

Author Response

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Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

In this paper the authors present the process to form polypyrrole coating film by “one-pot” synthesis. In particular they reports the method to have the emulsion polymerization of acrylate monomers and the oxidative polymerization of polypyrrole. They attest that this strategy reduce the solvent emission to air  and produce safer products and safer processes. This study presents the evaluation of the chemical structure of the polypyrrole synthesized during emulsion polymerization and the storage stability of the latices. In addition, the anti-corrosion effect of the incorporated polypyrrole component in combination with various pigments was assessed by electrochemical linear polarization technique and cyclic corrosion tests in a salt mist atmosphere.

In my opinion the manuscript is very interesting and it is well presented. However but it needs some minor revisions before the publication:

-FIG.1 FTIR: the authors should increase the resolution especially for the labels of peaks.

-FIG.8 The axes text should be increase in size.

-The authors should add some comments about the concept of “reduction of solvent emission” because in the paper was not emphasized sufficiently.

-The authors should add references to asses the novelty of this method used for this synthesis, in my opinion the paper shown an excellent description of the method but the authors should explain where in their opinion the method is better than others.

Author Response

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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

Comments and Suggestions for Authors

This manuscript investigates the coating performance of synthetic latices. Two kinds were involved. A series of experimental tests were conducted. The analysis was suitable. The authors thinks it can be considered if the authors can well respond the comments as follow:

(1) In the introduction section, most the references were over the last five years. As a academic research, some more materials about the advances in the relative areas should be involved, so as to make sure that the novalty is reasonable.

(2) For the introduction of the materials and methods, many knowledges were presented. However, it seems that some contents were repeated, while some important factors were missed, such as the detailed information on the coating process it self.

(3) For the experimental results, the results were well presented, however, the explation should better involve some more theoratical knowledges.

(4) The destination of the coating was to prevent the corrosion performance of the steel products. In this investigation, the authors have conducted a series of experimental tests on this issue. However, the some more results on the corrosion process of the steel can also be taken into account, especially in a meso scale. As the spatial distribution and the corrosion morphology of the steel materials can also be related to the coating effect: characteristics of the nonuniform corrosion of the steel bars extracted from the marine transportation infrastructures; impact of defects in steel-concrete interface on the corrosion-induced cracking propagation of the reinforced concrete; spatial distribution of corrosion products influenced by the initial defects and corrosion-induced cracking of the concrete;

(5) The conclusion should be reorganized in a more concise way by several seperated points.

Comments on the Quality of English Language

Suitable improvement is required.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript investigated the physico-chemical and stability properties of polyacrylate latexes with different polypyrrole loading and their anti-corrosion effect in combination with various pigments. The study is well supported by experimental results, but the “results and discussion” section really lacks interpretation. Additionally, there are some concerns that need to be clarified because they cause confusion to the reader:

1) The authors argued synthetizing polyacrylate latexes using a one-pot synthesis, but they did not justify why they used two emulsions containing acrylate monomers.

In line 129, they reported that the initiator was added to the reaction vessel after heating. This sentence is not congruent with the fact that the initiator was initially added in the reactor (table 1) and the first emulsion contained initiator as indicated in line 128 and table 1.

In the manuscript, the authors emphasized that polyacrylate latexes contained polypyrrole particles. (lines: 90, 95-96, 192 etc.) How can the authors confirm that the one-pot synthesis strategy allowed forming polyacrylate latexes and polypyrrole particles separately? Why a composite material polyacrylate/polypyrrole material cannot be obtained as reported in literature?

All the manuscript is structured on the assumption that polypyrrole particles were incorporated in the polyacrylate latexes. If the authors cannot demonstrate this statement, consequently, the objectives are not accomplished, and the study loses its relevance.

2) The authors presented 40 references but only reference [40] was used to compare the experimental results with literature. The results and discussion section lacks interpretation, the authors described their results without really interpreting and comparing them with similar studies reported in literature.

3) In line 352 the authors wrote, “The pH of individual latices gradually decreased from 1.9 to 1.6”. It is well reported in literature that pH decreases due to the autolytic decomposition of persulfate ammonium when used as initiator in radical polymerization processes.

4) The authors presented in table 3, the Zeta potential values of latexes which all negative values indicates that the latexes presented high colloidal stability but did not explain this results. The authors should indicate the isoelectric point of latex particles to better understand the effect of latex particles charges onto the latex stability upon pH changes.

From these reasons, I cannot recommend the publication of the manuscript in Coatings.

Comments on the Quality of English Language

The English quality is aceptable. 

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

It is excellent manuscript in over all aspects including methodology, conception, conclusive results.

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript "Polyacrylate latex coating binders comprising polypyrrole particles prepared by a “one-pot” synthesis" presents a relevant and interesting research on artificial latices finding their application in coating technology.

The research is well designed, with high scientific soundness and clear presentation of the results. All measurement and analysis methods presented in this research are adequate, and the research is detailed. References are relevant, and the conclusion is supported by the results. The manuscript was very interesting to read.

I recommend publishing of this manuscript after some minor improvements, and clarifications/additional discussion in the text. Specifically:

1. What were the sizes of the pigment particles used in the research? It would be an interesting information considering differences in the performances of different produced coatings. If possible, a table with this information could be added to Section 2.2.

2. Although the references are adequate and relevant, 16/40 are older than 10 years. I suggest adding some relevant references of newer dates to the manuscript, since the investigated topic is timely.

3. Line 291: Punctuation mark is missing at the end of the sentence.

4. The sentence in lines 358-363 is quite long - it would read better if broken down to two shorter sentences.

5. There is only one reference in the whole "Results and discussion" section ([40]). To increase the quality of the discussion, I suggest finding and adding some references to this section, to back up the discussed results. For example, to the statements in the lines 363-365, 433-436, as well as to the interpretation of FTIR-ATR and Raman spectra.

6. Why was the coagulum formation not observed for the latex L_{alkali_0}? (lines 392-393 and Table 3)

7. Please, specify the paint stripper used (line 455).

8. Could you discuss the possible reasons for the superior corrosion resistance of coatings from L_{acid_0.25} and L_{alkali_0.25} compared to other coatings (lines 527-531)?

9. A discussion about the reasons for differences in the anti-corrosion performance of the coatings with various pigments would further increase the quality of this already excellent manuscript (in section 3.8.).

Author Response

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Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Some improvement should be still made, for example, the conclusion should be presented in a more concise way, rather than list in a seven points.

Comments on the Quality of English Language

Improvements are required.

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript was not sufficiently improved, In the comments provided, the authors did not prove that their synthesis strategy allowed forming polyacrylate latexes and polypyrrole particles separately. Composite materials can be obtained. Consequently, the conclusion and discussion are not well supported.

Comments on the Quality of English Language

The English quality of the manuscript is aceptable.

Author Response

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Author Response File: Author Response.pdf