Behaviour of Thermochromic Coatings under Thermal Exposure

Round 1

Reviewer 1 Report

General Comments:

In this study, the author used three different matrix materials and two dispersion methods to prepare multiple groups of thermochromic coatings. The long-term monitoring and analysis of the spectral reflectance of coating was carried out by temperature agent and spectrophotometric agent. The color change behaviors of coating were evaluated according to the color differences at each temperature. In general, the presentation of this manuscript is satisfactory. The interpretations and conclusions are reasonable. More specific comments are listed below to improve this manuscript.

1. The author should improve the English language. There are so many cases of unusual, vague or unclear writing.

2. Please check through the manuscript and spell out full names of all abbreviations at the first use in your manuscript. For example, Line 17: L*, a*, b*, etc.

3. In line 48: The paragraph format should be consistent with the preceding and following paragraph format.

4. In lines 77-82: It is suggested to provide a dispersion diagram for the two dispersion methods, which is more intuitive.

5. In lines 106-113: The paragraph format should be consistent with the previous paragraph format.

6. In line 166: The last punctuation mark should be replaced with “;”.

7. In line 170: The last punctuation mark should be replaced with “.”.

8. Figure 2-Figure 11: The color discrimination of adjacent temperature curves is not obvious, and it is difficult to correspond to the legend. The differentiation degree should be reflected.

9. The position of Figure 10 should be consistent with Figure 2-Figure 9.

10. Results section: When analyzing each figure, it is suggested to display the image number at the beginning of the conspicuous segment.

11. Authors only described some test and calculated results, but did not deeply discuss results and explain their reasons. Enough discussion is needed. Or else, this manuscript is more like a research report.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors, the study is interesting and well developed but I have some concerns which are listed below:

- Please add the research hypotheses behind the experimentald design at the end of Introduction section

- I can't see any statistical analysis of the results, which is a fundamental aspect to evaluate the differences among experimental treatments in scientific journals. Please provide the readers with the statistical analysis that were carried out, and if there are not please explain why Authors think the study does not need statistic, also referring to already published studies in similar topic which did not apply inferential statistic for the evaluation of the results

- Sharpness of all the figures should be improved

- There are not literature references in Discussion section. Proper discussion of a scientific paper should not be a mere comment of the obtained results but also provide a comprehensive and concise comparison with the literature in the topic. A paragraph about study limitation is as well welcome

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments

In this paper, from the measurements of the behaviour of the coatings under temperature exposure, the effect of the primer used on the behaviour of the thermochromic pigment is observed. The topic of this paper involves the frontier of the discipline, which has important research significance and a wide range of application prospects. In general, the work is well done, while the conclusion is supported by the experimental and results. However, there are still some issues to be addressed before its acceptance.

1.        It is best to write an abstract that briefly summarizes the objectives, procedures and results of the experiment in one paragraph.

2.        Pay attention to paragraph formatting. For example, the second paragraph of the abstract and the second paragraph of the introduction should be indented by 2 characters in the first line.

3.        Pay attention to the position of the figure. The position of Figure 10 should be aligned with other figures.

4.        The pictures inserted by the author are not clear, and the author had better use lines of different colors to distinguish the changes in the data in the pictures, so that the reader can read more intuitively.

5.        Why is the dispergation time different in Table 2, while the dispergation time variable is controlled in Table 3？

6.        What is the mechanism of discoloration as the temperature changes?

7.        The full text paragraph format is not uniform.

 

8.        There are still some typos and grammar issues in the manuscript. Authors should carefully recheck the whole manuscript.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

 

Manuscript ID: coatings-2276118 entitled:

 

The behaviour of thermochromic coatings under thermal exposure.

Authors

Zuzana Tatíčková * , Jan Kudláček * , Michal Zoubek , Jiří Kuchař

 

General comment

This paper presents the results of the study on the thermochromic coatings, based on Leuco dye, commonly used in research for building cooling applications. The results show that by monitoring, the cooling behaviour of coatings, suitable base matrix can be selected; that ensures the long-term functionality of the coating and declares the temperature range of its use for safety purposes.

Some recommendations and observation remain:

1. The experimental part must be more concise. It is recommended to use the same notation.

In table 1, perhaps it is better to insert a column that, in addition to the already existing column in which the polymer matrix is ​​specified, the generic name should also be entered (and then also table 2 and 3 are easier to interpret).

 

2. Some notations are not sufficiently explained (VN21_IP02Ř, VN21_IP03Č). The curing time and temperature are not specified.

 

3. It is not clear in experimental part whether the samples studied are from pigmented polymer resins stored for three years from which films were applied, or from once applied films that were stored in a specific environment for three years.

Only at R314 in the end, in conclusion section  the author mentioned ” For coatings that are stored in a liquid state for a long time and then applied”

 

Specify the storing conditions.

 

4. Insert the thickness of the coatings in the table or text.

 

5. The data for the specified transition temperatures are determined experimentally or are given by the literature? It is good to specify the source.

 

6. Degradation is thought to pose a risk to the broad application of thermochromic coatings. As authors do not specify the storing condition, the possible degradation pathways are not known. Some organic components in the polymer matrix might formed in, which might could have an impact on ability of coating to change color.

If in time oxidation is present than eliminating oxygen from the media through oxygen scavenging devices is one of the possible strategies to overcome the problem. This aspect must be discussed in detailed way. (to discuss the possible degradation and interfering compounds and/or explain the differences in UV-Vis spectra).

 

7. It is not clear from the Figures, if the spectra presented are for the pigmented resin stored for 3 years. It must be specified in the text or even in the Title of the figures. It would be beneficial to be present a table containing similar chromatic data for freshly prepared pigmented resins, in order to better follow the changes that may occur.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

good job

Author Response

We thank the reviewer for his feedback and stimulating comments that helped to improve the quality of the article.

Reviewer 3 Report

Accepted in this version.

Author Response

We thank the reviewer for his feedback and stimulating comments that helped to improve the quality of the article.

Reviewer 4 Report

For R 115 and R259, the use of a diluent is mentioned. Some additional data is needed about the thinner used, as it has a major effect on the ability to regenerate the pigment.

Enter in text a few lines about possible discoloration mechanism with temperature change.

Author Response

The authors want to thank Reviewer 4 for his time and comments. The text added in the manuscript according to the reviewer’s comments is marked with blue color. The answer to the provided comments are given in following text.

For R 115 and R259, the use of a diluent is mentioned. Some additional data is needed about the thinner used, as it has a major effect on the ability to regenerate the pigment.
The name and type of thinner was added to R82 and R115. 

Enter in text a few lines about possible discoloration mechanism with temperature change.
Information about the possible influence of the thinner on the resulting IP02Ř properties has been added to R117 a R262.