Prediction of Contact Angle for Oriented Hydrophobic Surface and Experimental Verification by Micro-Milling
, Wenlu Meng 1,2, Jiawei Ni 1,2, Jie Pan 1,2 and Dong Wei 1,2
Round 1
Reviewer 1 Report
The article titled "Prediction of Contact Angle for Oriented Hydrophobic Surface and Experimental Verification by Micro-milling" discusses the prediction models of contact angle for oriented hydrophobic surfaces and provides experimental verification through micro-milling. The authors aim to explore the relationship between the contact angle and micro-structural parameters of rectangular microgroove structures.
The introduction section provides background information on the lotus leaf effect and the importance of directional hydrophobic surfaces in various applications. Previous studies on geometric microstructures and their effect on oriented hydrophobicity are discussed. The authors highlight the need for prediction models of contact angle for rectangular microgroove structures, as well as the challenges in acquiring such structures.
The article then delves into the theoretical basis of hydrophobicity and contact angle. It explains the concepts of surface tension, Gibbs free energy, and the contact angle models proposed by Young, Wenzel, and Cassie. The authors establish non-composite and composite state models for predicting the contact angle on rectangular microgroove structures based on minimum Gibbs free energy. The mathematical equations for these models are presented and discussed.
In the next section, the authors describe the experimental validation of their prediction models. They used 316L stainless steel samples and employed micro-milling technology to prepare rectangular microgroove structures with different dimensions. The cutting parameters and experimental conditions are explained in detail. The contact angles of the micro-structural surfaces were measured and compared with the predicted values from the models.
The results of the experimental verification indicate that the composite state prediction model of contact angle aligns more closely with the actual situation. The authors also observed that reducing the width of the convex platform leads to an increase in the contact angle. They provide numerical simulations and a three-dimensional surface diagram to illustrate the relationship between contact angle and micro-structural dimension parameters.
Overall, the article presents a comprehensive study on the prediction of contact angle for oriented hydrophobic surfaces using rectangular microgroove structures. The authors successfully establish prediction models based on Gibbs free energy and validate them through experimental verification. The findings contribute to the understanding of hydrophobic surfaces and provide insights for the design and preparation of oriented hydrophobic surfaces.
Minor editing of English language required.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript provides a comprehensive analysis of the prediction of contact angles on oriented hydrophobic surfaces, utilizing micro-milling techniques for experimental validation. The research's applicability in droplet-oriented delivery and microfluidics as highlighted in the conclusion adds considerable value to the field. However, there are several points that could use additional clarification:
1. The study revolves around the prediction models based on the minimum Gibbs free energy. Could the authors detail how these models were formulated, what variables were taken into consideration, and why the minimum Gibbs free energy was chosen as the key parameter?
2. The authors successfully prepared periodic rectangular microgroove structures on 316L stainless steel using micro-milling. Could the authors share further details about the micro-milling process, such as the settings used, challenges encountered, and how these challenges were addressed?
3. The study found that reducing the width of the convex platform increased the contact angle, hence, improving hydrophobicity. Could the authors explain the limitations of this process and if there's an optimal range for these adjustments?
4. The authors mention the accuracy range for the composite state prediction model is between 96.8% and 99.4%. Could they elaborate on how this accuracy was calculated and the measures taken to ensure the robustness of these models?
5. In terms of industrial production of oriented hydrophobic surfaces, what potential limitations or challenges might be encountered when scaling up this methodology? Could the authors elaborate on the economic viability of this process in an industrial setting?
6. The study indicates potential applications in droplet-oriented delivery and microfluidics. Could the authors expand on the specific real-world applications and benefits of their research within these fields?
The authors' work presents a promising advancement in the understanding and application of hydrophobic surfaces. Addressing these questions would further strengthen the manuscript and its impact on the scientific community. I look forward to reading a revised version of this study.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Xu et al presented Prediction of Contact Angle for Oriented Hydrophobic Surface and Experimental Verification by Micro-milling. This manuscript described here is to regard the approach to the contact angle prediction models of oriented hydrophobic surfaces were established based on the minimum Gibbs free energy, and the effect of micro-structural dimension parameters on contact angle was analyzed.
In my opinion, this work is of intereset to researchers in the field of a promising to useful for the design of controllable surface. Then, the precise periodic rectangular microgroove structure was obtained on 316L stainless steel by micro-milling, which is efficient and convenient. But it requires major revision before it becomes suitable for publication. The authors should consider the following comments to improve their manuscript.
MA1. The introduction must be improved by incorportating more recent references including geometric microstructures have been proven to form oriented hydrophobic surfaces and it should be described in more details.
MA2. In conclusion, please the contents detailed should be addressed including future scope and applications for better understanding of providing a favorable guidance for the industrial production of oriented hydrophobic surfaces in future perspectives.
The subjet may be interesting enough ijms but only after major, deep revision, if at all possible to resolve the above.
M1 Please Figure 9 should be presented and describe in more detail in a Figure.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The article as it stands is suitable for publication in "Coatings"
Reviewer 3 Report
The authors have improved the manuscript for publication.
