Layer-by-Layer Assembled Nano-Composite Multilayer Gas Barrier Film Manufactured with Stretchable Substrate
Round 1
Reviewer 1 Report
This work reports on the development of a flexible water barrier platform using a mixture of PDMS and Ecoflex as the substrate and GO/MMT as the coating barrier layer. The author demonstrated that by using 30 stacking layers of GO and MMT the developed platform offers excellent encapsulation against water along with good stretchability and optical transmittance. Overall, the paper was well written and experimental results were clearly explained. However, the novelty of this work compared to other studies reported in the literature needs need to clearly be clarified. In addition, there are some technical points need to be addressed before further consideration for publication in Applied Science.
- There are several works using GO as water barrier in the literatures, including DOI: 10.1039/C3TA12480K, and DOI: 10.1016/j.carbon.2019.01.037. The concept of pre-strained GO was also introduced previously, DOI 10.1038/s41598-017-09614-2. Please highlight the originality of the present studies to the previous reports. Furthermore, the authors mentioned the inorganic barrier to prevent water diffusion, such as SiOx (DOI: 10.1073/pnas.1605269113; DOI: 10.1002/aelm.201700077) and SiC (DOI: 10.1021/acsnano.9b05168; DOI: 10.1002/adfm.202004655) that can be transferred on to a soft substrate. Please compare the use of GO composite and these inorganic thin films.
- Did the authors compare the performance of GO/MMT double layers with GO or MMT only? Please explain the role/function of each layer in protecting against water.
- Why did the author try with 30 layers? How is the thickness dependence of the water barrier? At which thickness, the WVTR and OTR become saturated.
- The caption of Figure 5 should explain the difference between the sub-figures (a),(b), and (c).
- What were the thicknesses of the substrate and the coating layer?
- In figure 3, the authors used the drop-casting method to deposit GO and MMT layer by layer on to Ecoflex/PDMS. The reviewer concerns about the uniformity of this method. Specifically, for large scale device (in the order of cm), the thickness of the deposited layer may significantly vary. On the other hand, as the authors need to stress the substrate, it is unlikely possible to use standard method such as spin coating to form uniform film. Please add a discussion on this.
- The reviewer assume that the first coating layer bonded to the Ecoflex/PDMS substrate via the Van der Walls force. The film may experience delamination after several stretching cycle. Please comment this point.
- There are some typos in the manuscript. The abbreviation in the abstracts should be defined in the same sentence.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work presents a sufficient study regarding the Layer-by-Layer assembled nano-composite multilayer gas barrier film manufactured with stretchable substrate. Results and methodology followed are convincing.
However, as a basic research there are some more characterization methods that are need to be performed. FTIR is required for the characterization of such materials. In addition, some TEM images of the suspension is also suggested. The durability of the nano-composite multilayer and degradation mechanism has to be established and proved with more specific manner. More details regarding the drop casting method are also needed. In addition, in line 186 you refer that ‘..good interlayer bonding via electrostatic attraction..’ how can you prove this state (literature, experimental data?)? The discussion part has to be further developed. Moreover, the English language and style required to be improved. Considering the aforementioned, this manuscript is reconsider after major revision (control missing in some experiments).
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed point by point my questions in the response letter. However, these points were not fully reflected in the revised manuscript.
For instance, the authors did not revise the introduction to highlight the originality of this work compared to other studies on GO. In addition, a comparison between inorganic barrier and the proposed platform was not included, as questioned in the previous review.
Please response to these points and highlight all changes in the manuscript to make it easy for reviewer to follow and track.
The writing of the paper needs to be improved.
Author Response
According to your comments, we revised the manuscript. In addition, we revised the English language.
Reviewer 2 Report
FTIR and TEM analysis could improve the manuscript. However, their analysis is insufficient. Further clarifications are required. Figure 3 is of low quality and the respective analysis (lines 116-122) has to be supported by literature. In addition, the following comments have not been taken into consideration by the authors:
'More details regarding the drop casting method are also needed. In addition, in line 186 you refer that ‘..good interlayer bonding via electrostatic attraction..’ how can you prove this state (literature, experimental data?)? The introduction and discussion part have to be further developed. Moreover, the English language and style is required to be improved.'
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
The authors have updated and highlighted the changes in the revised manuscript. However, the references for the introduction is still not comprehensive.
Please cite relevant papers to support your claim as mentioned in the previous review rounds; for instance "Also, inorganic layers were fabricated by vacuum pro-30 cesses. However, vacuum processing has the disadvantages of low production efficiency 31 and high production costs."
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Indeed, this manuscript has been revised. However, the analysis using Zeta-potential, SEM and FTIR section need further clarifications supported by literature. In addition, the discussion section is not sufficient.
Considering the above mentioned regarding the version 3, this manuscript is reconsider after major revision.
Author Response
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Author Response File: Author Response.pdf
Round 4
Reviewer 2 Report
The version 4 is indeed updated and most of the comments have covered. However, more details at the Discussion part are needed.
Author Response
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Author Response File: Author Response.pdf
