Resonant Soft X-Ray Scattering Reveals Chromophore Domains in Polymer Doped with Disperse Orange 11 Dye

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript “Resonant Soft X-ray Scattering of Chromophore Domains in Polymer Doped with Disperse Orange 11 Dye” by Elliot Steissberg et al. deals with the comparison of RSoXS data with domain model’s predictions. The main finding is the domain size being independent of the dye concentration, which implies modification / extension of the domain model. This can improve the understanding and prediction of self-healing materials.

The manuscript is interesting for publication in Applied Sciences.

The manuscript is well written. However, several minor aspects of the manuscript should be improved.

1. Abstract, line 18: “Future studies are planned … ” should be not in the abstract. Better use the next sentence: “This work provides direct experimental evidence ... . For further investigation accounting for domain topology and geometry…will be investigated in future studies.” Similar to text in the Conclusions.

2. Citing references: Please improve the way citations are included in the text. Often space characters are missing: E.g.line 27 should be: “… nonlinear optical [2] and lasing materials [3-5]…

Or the citation is after a comma or a point: line 29, line 32, line 33, ….

Also some citations are not grouped: line 37: [12-14], line 61: ref 40 appears twice

3. Section 2.2 RSoXS: I think one important reference should be added:

B. A. Collins, E. Gann, J. Polym. Sci. 2022, 60(7), 1199. https://doi.org/10.1002/pol.20210414

4. Figure 4 and discussion: Line 268. “The peak centers are for the most part all at the same q value…” Can you highlight the peak values in the plot? Maybe a small trend can be seen?

Also Q is given in a different unit than in Figure 2 and 3.

5. References

Some DOIs are missing.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

After careful examination of the manuscript "Resonant Soft X-ray Scattering Studies of Chromophore Domains in Polymer Doped with Disperse Orange 11 Dye," I must recommend rejection based on several fundamental concerns regarding the experimental design, data analysis, and interpretation of results.While the authors attempt to provide direct evidence for chromophore domains hypothesized in their self-healing model, the work suffers from significant methodological limitations and fails to convincingly demonstrate the claimed domain structures.

1. The paper lacks basic characterization of film uniformity, thickness variations across samples, and potential phase separation effects. How can the authors exclude the possibility that the observed scattering features arise from sample heterogeneity rather than true molecular domains?
2. The double subtraction procedure appears problematic. Why is the power law fitting limited to only the 1% sample, and how does this justify applying the same slope parameter to all other concentrations? This approach seems arbitrary and potentially introduces systematic errors.
3. The authors acknowledge that peak positions remain essentially constant across concentrations, contradicting their model's prediction of concentration-dependent domain sizes. This fundamental discrepancy undermines the central claim that RSoXS confirms the domain model.
4. he scattering features appear only in a narrow q-range (0.05-0.08 Å⁻¹). What happens at higher q-values where other structural features might be observable? The truncated analysis limits the structural information that can be extracted.
5. No error analysis or statistical treatment of the data is provided. How many samples were measured for each concentration? What is the reproducibility of the observed features?
6. Beyond neat PMMA, no additional control samples are examined. What about partially degraded samples or samples prepared under different conditions that might alter domain formation?
7. The authors assume spherical domain geometry to calculate sizes, but acknowledge that molecular arrangements could be chain-like or other configurations. Without additional structural probes, this assumption remains unsubstantiated.
8.  Why were only two specific energies (270 eV and 284.5 eV) selected? A more comprehensive energy scan across the carbon K-edge would provide stronger evidence for the claimed resonant enhancement.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Elliot Steissberg and co-authors have used RSoXS to characterize the domain size of DO11 molecules doped into PMMA polymer. The authors claim that their experiment provides the first direct evidence of the existence of dye domains in the PMMA matrix, consistent with the domain model hypothesized previously.

The authors present a well-structured manuscript that makes a meaningful contribution to the field. The strength of the manuscript includes
1) detailed and comprehensive description of experiment configurations and data analysis. 
2) providing evidence of a resonant scattering enhancement between q= 0.05 Å−1 and 0.08 Å−1 corresponding to a size of between 62.8 Å and 39.3 Å.
3) honestly present the experiment data of the 6.5 wt\% sample, which is not consistent with the expected trend

The weakness of the manuscript includes
1) The author hypothesized that the unexpected experiment results on the 6.5 wt\% sample can be due inhomogeneity of the samples or potentially problematic background-subtraction protocol. If the authors have doubts about sample quality or the correctness of their data analysis protocol, have the authors attempted to repeat the experiment/analysis? We greatly appreciate that the authors honestly presented the unexpected experiment data, but it is the authors' responsibility to rule out trivial explanations such as bad sample quality or incorrect data analysis. Otherwise, it creates doubts whether other results presented in the same manuscript are reliable or trustworthy. 

In general, this is a good quality manuscript that meets the standards of publication. With the author addressing the aforementioned weakness, I support its publication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors, 

The article concerns an interesting and relevant issue. The topic is part of long-term research on self-healing mechanisms in optical materials and has potential practical applications. Despite its interesting objective, the work has numerous weaknesses in structure and data interpretation, which are as follows: 

1. The introduction is too extensive, disorganized, and largely takes the form of a historical overview rather than leading to a clearly formulated research problem.
2. The article does not clearly state the purpose of the study. It should be added as the last paragraph in the Introduction section. 
3. The style is sometimes narrative and imprecise (“what makes our model so useful is...”), which does not correspond to the conventions of scientific publications.
4. The discussion section often repeats content from the introduction or summarizes the results. Perhaps consider merging the Rezults and Disscusion sections. 
5. No clear justification for the choice of experimental parameters, e.g., energy range, normalization procedures, or smoothing window in data analysis. Add information of this. 
6. The “double background subtraction” process is described briefly and does not include information about measurement errors. 
7. The main statement (the work provides “the first direct evidence for the existence of domains”) is too general. The scattering peaks obtained may result from other morphological effects (e.g., phase separation of the PMMA matrix). Rewrite this.
8. The authors themselves admit that the size of the domains does not depend on the concentration of the dye, which contradicts the model on which they base their interpretation. This contradiction is worth discussing in more detail. 
9. Many linguistic errors, inconsistent use of abbreviations and symbols (e.g., “Å−1” and “1/Å”).
10. Some of the sources are outdated or repeated. It is worth looking for more recent publications. Publications 16 and 40 are identical. Publication: Spectroscopic studies of the mechanism of reversible photodegradation... J. Chem. Phys. 2016, 144, 114902. - cited several times under a different number. 
11. Add specific applications to the “Featured Application” section. Currently, the information is too general. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

The review file is included in the attached document.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 6 Report

Comments and Suggestions for Authors

Review of the manuscript entitled ‘Resonant Soft X-ray Scattering Studies of Chromophore Domains in Polymer Doped with Disperse Orange 11 Dye’

Domain models explain why the healing rate decreases at higher temperatures due to the thermal breakup of domains for disperse orange 11. Authors claim that while these models are useful, they depend on domains whose morphology is unknown and of which no direct observations have been made. The study provides direct physical evidence of domains using Resonant Soft X-ray Scattering.

The study is very interesting and deserves to be accepted with additional revisions for improving the quality of the study. The results are in the scope of the journal.

- The manuscript must be polished from English spellings

- In the figure 4 what are the color for the different wt%?

- line 278 it is difficult to follow the explanations if we don’t have the representation of the curve for 6.5 wt%

- the sentences: ‘The inconsistency in low-q data for all samples implies it may not have much use in fitting the high-q region at all. The data in Figure 3 is much more consistent with the expected trend.’ are difficult to understand. What is the expected trend? Why are the data much more consistent?

- The conclusion must be re-written with the main results of the study.

- Could the method be used with other materials? For example, the material is prepared with guest-horst molecules but could it be prepared with attached molecules to the main chain?

Could the method be used for any photoisomerized molecules?

- Authors must be more details on the calculations.

- Authors could also compare the results with the following work on photoisomerization of azobenzene molecules: Daniel Keefer et al., Imaging conical intersection dynamics during azobenzene photoisomerization by ultrafast X-ray diffraction, PNAS 2021 Vol. 118 No. 3 e2022037118

and rhodopsin: Hitoshi Nakamichi et al., Photoisomerization Mechanism of Rhodopsin and 9-cis-Rhodopsin Revealed by X-ray Crystallography

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The author has addressed my concerns, so it can be published.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for your careful and comprehensive revision. Most of the earlier comments have been fully addressed. The discussion provides a balanced interpretation of the results and appropriately limits the conclusions.
There is only one minor comment: The introduction could still be shortened slightly for greater clarity.

Overall, the manuscript is significantly improved and scientifically sound.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

No comments

Author Response

Please see the attachment.

Author Response File: Author Response.pdf