Capillary Rise: A Simple Tool for Simultaneous Determination of Porosity and Thickness of Thin Silica Coatings
, Inimfon A. Udoetok 3,*, Andrew T. Tyouwa 2,4, Clement O. Obadimu 1 and Hamza S. Al-Shehri 2,5
Round 1
Reviewer 1 Report
This article is written well.
The authors could compare the porosity and coating thickness of C-8000 to C-2000 using this simple tool in the manuscript.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work is to introduce a porous coating method by spin-coating hydrophobic fumed silica onto glass slide. Although the authors have presented lots of experimental results, the motivation and innovation of this work has not been mentioned. This makes this work sounds like a experimental report rather than research paper. In addition, the porosity of the materials are only calculated via the impreganation experimental results. Additional experimental methods are required to validate such results. It is also interesting to point out that the selection of coating speed for following experiment is pretty random. Even though the authors applied 6 different coating speed in the beginning, no good reason has been given when they proceed to conduct later on experiment with C-2000 method. Can those results be repeated? Last but by no means the least, the importance of the work and the comparisons between other coating methods, other coating materials have not been provided.
Thus the reviewer would suggest reject of the manuscript.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The authors report simultaneous determination of porosity and thickness of thin silica coatings through oil-infiltration into the coatings. They measured the mass of coatings before and after squalene infiltration and calculated the volume of solid coating and pore volume assuming squalene completely filled the pores. Then, they calculated film height and porosity.
However, the authors assumed the squalene completely filled all the pore volume. However, the infiltration of squalene will depend on the pore size of silica coating. Squalene might not infiltrate into the small pores completely. Also, the squalene could might just cover the surface of pores rather than completely fill the pores. Also, since the thickness is so small, squalene volume remained on the surface of the coating will be critical. So, this method and calculation cannot be applied universally. The authors should clarify when this method can be used. The authors calculated the pore volumes but did not confirmed them using the more accurate measurement method.
Because there are other good ways to measure the thickness accurately, there is no reason to estimate the uncertain thickness using this method. For the calculation of porosity, it would be better to calculate total volume of coating from thickness and area, and calculate volume of silica coating from mass and then calculate porosity. Although this method can be described in the experimental section of certain paper as a very rough estimation method of porosity, I don’t think this manuscript is suitable for published as an independent paper
Quality of English is acceptable. But, sometimes, the selection of vocabulary is
not proper.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The paper is suitable to publish now
Author Response
N/A
Reviewer 2 Report
The authors have addressed most of the technical issues in the previous version of manuscript, thus the reviewer would suggest accept it as is.
Author Response
N/A
Reviewer 3 Report
I don't think the manuscript content is significant to be published in a journal paper. And people can easily think of this method but they usually don't use it because it is not accurate. This can be just described in experimental section of a paper.
It is well written.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
