Impact of Molecular Weight on Anti-Bioadhesion Efficiency of PDMS-Based Coatings
, David Mimeau 2, Eric Balnois 3, Karine Réhel 1, Fabrice Azemar 1 and Isabelle Linossier 1
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsTitled "Impact of molecular weight on anti-bioadhesion efficiency of PDMS based coating", this study examines the relationship between the relative molecular weight of polydimethylsiloxane (PDMS) and its anti-biofouling efficiency. Although the work is original, I have some suggestions.
1. The article lacks basic performance data for the coating, such as adhesion and hardness.
2. The author found no relationship between relative molecular weight and surface energy, and there was little change in surface energy, but there was a difference in anti-biofouling efficiency. No reasonable explanation was provided.
3. The explanation of the impact of relative molecular weight on surface roughness of the coating is insufficient. Since it is suggested that the network structure may be the influencing factor, further exploration of how it affects roughness should be conducted.
4. In the article, regarding the impact of roughness on bacterial adhesion: The author states that increasing nanometer roughness can inhibit bacterial adhesion, but the coating with higher roughness in the article actually exhibits lower efficiency, which was not explained and should be clarified.
5. Too many unresolved issues are raised, such as crosslinking degree, mobility, free volume, and supplementary data could be provided.
6. The article concludes that the anti-biofouling performance is better when the relative molecular weight is 2-4 kg.mol-1, but only two sets of data cannot cover the entire range.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this article, the authors investigated surface characteristics and anti-bioadhesion properties of different molecular weights of PDMS coated on glass slides and PVC substrates, along with a 12-month marine field test. Regarding the good quality of the experimental design, results, and figures, there are questions and concerns that should be addressed before consideration of publishing this manuscript in Coatings. The corresponding comments and suggestions are shown below.
Line 39-40:
“…such as polydimethylsiloxane have shown…”
- polydimethylsiloxane (PDMS)
Line 80:
“In another study Gray’s group showed…”
- In another study,
Line 147:
“the coatings solutions were…”
- the coating solutions
Line 151-153:
“The preparation was coated immediately after mixing onto a glass slide for surfaces characterizations and on PVC plates for marine field test.”
- Please briefly describe the technique used to apply the coatings onto the substrates, e.g. dip or spray coating or other. Coating conditions and parameters should also be included.
Line 183:
- Equation 1 should be (W0-Wex)/W0
Line 203-204:
“Topographical Images were…”
- Topographical images
Line 232-233:
“the samples were coated on the two sides of the PVC surface: one exposed to UV light, the other to shade.”
- At first, it's quite confusing whether the authors use UV lamp or UV light from the sun before reading the results. Therefore, the authors should specify that this experiment was performed under exposure to UV radiation from sunlight.
Line 295:
“…as showed in…”
- shown
Line 307-309:
“The different PDMS polymers showed similar SEM morphologies, suggesting that at this scale, the distance between crosslinking nodes, hence the molecular weight, did not affect the morphology of the PDMS network.”
- From supplementary data Figure S1, the surface of PDMS-2.5K shows a slightly rougher surface with some kind of bumps and grooves, which is hard to tell at this magnification. The authors might provide more discussion on this because the AFM results indicate that the surface roughness tends to increase for higher molecular weight samples.
Line 344-346:
“However, these values were in good accordance with previous studies, as elastic moduli for fouling release coating are typically ranged between 0.2-9 MPa [3,21–23].”
- The authors may also add more discussion on the correlation between typical PDMS molecular weight and the elastic modulus with the supporting references here.
Figure 6:
- Figure 6 should contain Figure 6a and 6b. Please put the corresponding a and b letters in each image. Also, in the paragraph above, please also specify as Figure 6a or Figure 6b (Line 349 and 354).
Line 419:
“In fact, Liu et al…”
- Missing reference number here and no citation information found in the References section.
Line 441-443:
“Nevertheless, in our study the difference in anti-bioadhesion activity during immersion was observed depending on the molecular weight of PDMS polymer, thus on some properties of the network.”
- It's difficult to confirm the dependence of molecular weight of PDMS on anti-bioadhesion activity. However, the effect of surface roughness might be more pronouce. The RMS results from AFM analysis may be just slightly different. But if we look closely at AFM images, we can see that the roughness scale range of PDMS-6K and PDMS-10K is in between +/-25 nm, which is greater than others. Therefore, the authors might need to revise the discussion regarding the above statement.
Line 465-466:
“In situ immersions results showed that in the presence or absence of solar radiation different communities of organisms adhere on the surface, leading to differences of the coating performances.”
- I'm not sure what the authors were trying to mention here. Does this mean the anti-bioadhesion performance of the coatings?
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript presents data on the effect of the Mw of polydimethylsiloxanes on their bio-adhesion inhibition efficiency. It is interesting with limited novelty. The language is adequate but a rechecking to correct some minor mistakes. I recommend publication after the following major revisions
11. The abbreviation RTV needs definition.
22. Page 2 lines 105-107. “The three vinyl terminated polydimethylsiloxane (Mn: 800 kg.mol-1 , PDMS-V0.8K; Mn: 6000 kg.mol-1 , PDMS-V6K; Mn: 9400 kg.mol-1 , PDMS-V10K) were acquired from Gelest Inc. ” kg.mol-1 or rather g∙mol-1 as indicated in the introduction?
33. Page 3 lines 125-127. “The resulting product was cooled to room temperature and filtered to remove solid by-product. The volatiles were then removed under reduced pressure.” Please define the solid by-product and the volatiles.
44. Page 3 lines 132. “General synthetic pathway of modification of polymers with crosslinked group.” Do you mean cross-linkable as in the text below?
55. In Table 1 the footnote with the explanations of the and b marks (columns 4,5) is missing.
66. The presentation of the NMR results is inadequate. First, there is a paragraph in the experimental section that should be moved to the results and discussion. A full catalog of the peaks together with the integrals is required along with the provider of the deuterated chloroform.
77. Page 4 lines 164-165 “apparition of allyl protons peak at 6-5 ppm (m, 2 H, CH2CHCH2) and 5-4 ppm (m, 4 H, CH2CHCH2)” In both cases the hydrogens marked in bold are the same and I suppose a double bond is missing.
88. The number of citations is rather limited. The issues analyzed in the discussion section are well supported though.
99. In my opinion the potential for the application of these coatings to ships is rather limited since their production requires a two-stage reaction, high temperatures, toxic solvents, and expensive starting materials. For these reasons, I expect in the conclusions section of the revised version a paragraph with arguments on the opposite.
Comments on the Quality of English LanguageThe language is adequate but a rechecking to correct some minor mistakes.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe review is attached
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors addressed most of the issues. The manuscript may now be accepted
