Robust Superhydrophilic/Underwater Superoleophobic Surface with Anti-Abrasion and Anti-Corrosion Performances Based on Laser Ablation

Round 1

Reviewer 1 Report

1. There is any particular reason to select HCl and NaOH solution?

2. In line 112 check typo error " inset area".

3.  What is the reason for choosing dichloroethane as reagent?

4. What is UOCA?

5. What is the effect of angle above 155 degree?

6.  The author insert high quality images for better understanding? Ex. Fig 7 EDX mapping is not visible.

7. Use standard deviation graph in figure 8.

8. Author need to explain the effect of silicon oxide in the component.

Minor Revision

Author Response

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Reviewer 2 Report

Chemical corrosion occurs at metal surface exposed to very high temperature, in the absence of humidity. During this corrosion, oxide films are formed on the metal surface (typical example, is the chemical corrosion of metals after their metallurgical production ). Thus, the use of the “chemical corrosion” expression is very wrong.

The authors must prove their results that there is an oxidizing process, change in the nanostructure during the abrasion, density of nanostructure, hexagon frame as protector and more… because they present only the SEM images y their elemental analysis. There are additional techniques, for example XRD, which could give an information about the crystal cell structure, size of the crystals, their change in structure, and more. And after that, suggest the MECHANISM, which provided the protection of the studied material.

Author Response

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Reviewer 3 Report

This study presents an innovative use of laser ablation for multi-scale patterning (at the nanometer and micrometer lengthscales) for producing resilient hydrophilic surfaces that are also superoleophoboic in underwater conditions. An underwater oil contact angle of ~165 degrees is demonstrating. The performance under mechanical abrasion and in harsh chemical environments (pH ranging from 1-14) is also evaluated. The laser ablation patterned structure shows good performance under abrasion and chemically corrosive environments. Overall, this study is based in sound experimental design and scientific principles, and is relevant to the readers of Coatings. I therefore recommend it for publication. 

There are some points that I would like the authors to address: 

1. There are several minor typographical errors in the manuscript. Please fix these. For example: 

- In the abstract, Line 21, space between "abrasion" and "and"

- In the Introduction, Line 37, space between "superoleophobic" and "due"

- Page 2, Line 46, "In addition. Many" to "In addition, many"

2. In the introduction, when referencing underwater anti-fouling surfaces, please also cite: Also cite: Liao, Z., Wu, G., Lee, D., & Yang, S. (2019). Ultrastable underwater anti-oil fouling coatings from spray assemblies of polyelectrolyte grafted silica nanochains. ACS applied materials & interfaces, 11(14), 13642-13651. and other related articles. The literature review needs to be more thorough, there is a lot of work in this field in the past 3 years or so.

3. In the introduction, for the sentence, "Nevertheless, the nanostructure 58 obtained by physical or chemical methods are not robust enough, especially in corrosive environment or under abrasion." - Reference(s) are needed for this statement. 

4. Please provide more details on the nanosecond pulsed laser ablation to create the irregular rough surface. What was the laser make/ model? What was the laser pulse energy? What was the spot size that the laser was focused to?

5. Why was a honeycomb pattern selected for the laser ablation patterning? What was the geometric dimensions of the honeycomb unit cell?

6. What was the difference in laser parameters used to create the rough surface on the silicon, and then to create the honeycomb pattern?

7. For the abrasion tests, approximately how fast were the samples dragged on the sand paper?

8. In Section 3.1, the choice of words "extremely rough" is very subjective. Can the authors measure the RMS surface roughness using either laser confocal microscopy, optical profilometry or atomic force microscopy?

Overall, the quality of the English is good - there are no major grammatical errors in the text. 

Author Response

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Round 2

Reviewer 2 Report

Introductory part:

“Nevertheless, the nanostructure obtained by physical or chemical methods are not robust enough[36], especially in corrosive environment or under abrasion.”

And more, in p.3.2: “As we all know, the silicon is stable and hard to corrosion by acids and bases, but the 182 silicon oxides resulting from laser ablation are susceptible to environmental influences.”

Comment: Please, provide examples of the corrosive environment and what kind of susceptibility has been reported. This comment is more important for the discussion of the results in p.3.2.

“The prepared surface shows robust superhydrophilicity and underwater super- 66 oleophobicity even after 6 hours chemical corrosion and cyclic abrasion” (the end of the paragraph, before 2.2. Materials).

Comment: Don’t use the word “chemical” corrosion.

“2.2. Corrosion resistance: HCl and NaOH solutions with different concentrations were used to simulate the pH values of different environments”

Comment:  However, only solution of pH =14 has been used as a testing solution. I suppose that it was formed only by NaOH, and the acid HCl was not needed.

During the text, several times the pH has been written as PH. Please, make a correction.

Results: Could you provide a structure of SiO2 of the silicon wafer before and after laser ablation, please? (3.1.Surface morphology)

p.3.2: What happen to the SiO2 structure after exposure to pH=14 solution? How the structure changed?

The submitted article still needs revision and improvement.

Author Response

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