Hydrophobic Prediction Model and Experimental Study of PMMA Surface Microstructure Prepared by Femtosecond Laser Direct Writing

Round 1

Reviewer 1 Report

Reviewer:

Comments to the Author

Title: Hydrophobic Prediction Model and Experimental Study of PMMA Surface Microstructure Prepared by Femtosecond Laser Direct Writing

The authors should apply the following comments. So, the manuscript can be accepted after minor revision.

 

1. After the following sentence should be the corresponding references: At present, many researchers have proposed many methods to prepare hydrophobic microstructures on PMMA surface (Page 1, Lines 31-33).

2. Last paragraph in the introduction section should be improved.

3. Section 6 (Analysis of results, discussion and conclusion) should be written in more detail and compared with literature data. In general, this section should be improved.

Comments for author File: Comments.doc

Author Response

Response to Reviewer 1 Comments

Dear Reviewer:

Thank you very much for your comments on this article: ID: coatings-2037296.

We would like to thank you for your efforts contributed to this paper. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. According to these comments, we have carefully revised the paper. Our detailed responses to your comments are as follows: 

1. Comments:

Abstract: After the following sentence should be the corresponding references: At present, many researchers have proposed many methods to prepare hydrophobic microstructures on PMMA surface (Page 1, Lines 31-33). 

Response:

Thank you for the comments. We have marked the corresponding references.

Special thanks to you for your comments. 

2. Comments:

Last paragraph in the introduction section should be improved. 

Response:

Thank you for your comments. We have rewritten the last paragraph in the introduction section(page 2 and 3).

Special thanks to you for your comments.

3. Comments:

Section 6 (Analysis of results, discussion and conclusion) should be written in more detail and compared with literature data. In general, this section should be improved. 

Response:

Thank you for your comments. We have rewritten the Section 6 (Analysis of results, discussion and conclusion) (page 20).

Special thanks to you for your comments.

Those comments are all valuable and very helpful for revising and improving our pape. Your comments make this article more rigorous.

Once again, thank you very much for your comments.

 

Yours sincerely,

Bangfu Wang

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper uses laser processing to control the surface properties (hydrophobicity) of PMMA and analyzes it by wetting theory.

 

1. The author should supplement the information on the design of the secondary structure applied to this paper in more detail. And the reason why the secondary structure was made in the shape of cruciform is not explained, so it needs to be added. In addition, information about the width and spacing of the structure is provided, but does not deal with the depth. Depth is also a factor that affects wetting, and I wonder if there is a reason why it hasn't been mentioned. It seems that an explanation of the relationship between wetting and aspect ratio must be added.

 

2. Although it is mentioned in the paper that PMMA changes from hydrophilicity to hydrophobicity after laser processing, there are no results to support this in the text, so it is necessary to add it.

 

3. In table 3-2, when the output is fixed at 4W, when the scan speed is changed from 0.7 to 1.0 and 1.1, the width and depth of the groove do not seem to change linearly. It seems necessary to add data showing the difference in groove spacing by making the scan speed or output range wider rather than a simple output fixing method.

 

4. It is necessary to check the numbering of figures and tables indicated in the thesis. (ex. 5page table 3-2)

Author Response

Response to Reviewer 2 Comments

Dear Reviewer:

Thank you very much for your comments on this article: ID: coatings-2037296.

We would like to thank you for your efforts contributed to this paper. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. According to these comments, we have carefully revised the paper. Our detailed responses to your comments are as follows: 

1. Comments:

The author should supplement the information on the design of the secondary structure applied to this paper in more detail. And the reason why the secondary structure was made in the shape of cruciform is not explained, so it needs to be added. In addition, information about the width and spacing of the structure is provided, but does not deal with the depth. Depth is also a factor that affects wetting, and I wonder if there is a reason why it hasn't been mentioned. It seems that an explanation of the relationship between wetting and aspect ratio must be added. 

Response:

Thank you for the comments. It has been added. The reason why the secondary structure is made into a cross shape is that in the image processed by the processing equipment, the effect of  "cross-shaped" secondary microstructures is ideal, and there are some defects in the preparation of other structures, which affect the hydrophobic performance. 

The contact angle formula under Wenzel model() containing depth(h), and the contact angle of Cassie model() without depth(h). In addition, the predicted value of the Cassie model is similar to the experimental value, but the actual value is smaller than the theoretical prediction value. This conclusion is consistent with the reference(Chen long Zhang. Study on the Surface and Water collection Haracteristics of Superhydrophobic-superhydrophilic Biomimetic Structure Prepared by Laser[D].Wenzhou University,2021), Therefore, in this paper, the primary and second structure depth of the secondary microstructure are fixed. That is the primary and second structure depth of the secondary microstructure are 160μm and 50μm, respectively.

Special thanks to you for your comments. 

2. Comments:

Although it is mentioned in the paper that PMMA changes from hydrophilicity to hydrophobicity after laser processing, there are no results to support this in the text, so it is necessary to add it. 

Response:

Thank you for your comments. It has been added. It is clarified in the paper that the measured PMMA inherent contact angle is 64°(Page 3), which indicates that the PMMA surface is hydrophilic. The contact angle of PMMA after femtosecond laser processing is greater than 90°, which indicates that PMMA changes from hydrophilic state to hydrophobic state after laser processing.(Page 16-17).

Special thanks to you for your comments.

3. Comments:

In table 3-2, when the output is fixed at 4W, when the scan speed is changed from 0.7 to 1.0 and 1.1, the width and depth of the groove do not seem to change linearly. It seems necessary to add data showing the difference in groove spacing by making the scan speed or output range wider rather than a simple output fixing method. 

Response:

Thank you for your comments. The femtosecond laser direct writing process is very complex and affected by many factors. The scanning speed is determined by combining the relevant references and the actual processing effect. Thank you for your suggestions. We will specially study the femtosecond laser direct writing process in the future to improve the model.

Special thanks to you for your comments.

4. Comments:

It is necessary to check the numbering of figures and tables indicated in the thesis. (ex. 5page table 3-2) 

Response:

Thank you for your comments. I have checked and modified the full text.

Special thanks to you for your comments.

Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. Your comments make this article more rigorous.

Once again, thank you very much for your comments.

 

Yours sincerely,

Bangfu Wang

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

 

Efforts has been made to organize the experimental description. The replay of authors are satisfactory.