Preparation of Multicomponent Biocomposites and Characterization of Their Physicochemical and Mechanical Properties
Round 1
Reviewer 1 Report
Peer-Review of “Preparation of Multicomponent Biocomposites and Characterization of their Physicochemical and Mechanical Properties” by Anisimov, et al. submitted to Journal of Composites Science.
General Comment: Major Revision Required. This manuscript is quite interesting, and has some very good results and conclusions. I do not think further experiments should be necessary but the manuscript does require significant attention before I would consider it for publishing. Some areas are lacking in substance, need further clarification, and require more thought put toward conclusions, however. I believe the study will be improved and ready to publish after the authors consider and address each of the following discrepancies.
(1) Line 31: Is “manifold” a typo? Do you mean “multitude” or some other descriptor?
(2) Lines 43-44: How are “blending” and “preparation of composites” methods of “functionalization”. When I read “functionalization”, I think you mean “chemical modification”. Request you clarify this sentence by describing these some methods as “non-covalent” and some as “covalent” (i.e., grafting would likely be a covalent approach to making polymer composites”). In fact, I think you’re data strongly suggests these composites are “non-covalently modified”. It makes chemical sense that the PANI and CHT will hydrogen-bond with each other, though your data doesn’t clearly show that….almost no good characterization method will clearly indicate that with bulk composites (in my experience with silanized cellulose for example).
(3) Lines 48-51: Poor sentence structure. The sentence starting with “Thus…” (line 48) isn’t a complete sentence… The sentence starting with “For example…” (line 49) needs to be reworded (see .pdf of written comments for suggested re-write).
(4) Line 74: Reword. Poorly structured sentence.
(5) Lines 75-79: This paragraph (concerning PVA) just hangs out there. Very poor transition “in” and “out” of the paragraph. Need to discuss “why” would you even consider using PVA in these kinds of composites? (i.e., what do they lack that PVA provides, etc etc).
(6) Line 95: Place period at end of 98%, capitalize “Sulfuric acid” and treat as a separate sentence, which would be in rhythm with the rest of your “materials” section.
(7) Lines 100-106: Just delete this section and roll it in with the following section. It primarily describes “preparation of polymer composites” and not “shorthand notation” anyway…. You can put the “shorthand notation” description (which I like and I think IS important) as the last 2 sentences of the section 2.2 (Preparation of Polymer Composites) section.
(8) Line 111: Please state how much (wt%?, mol%, etc) of APS added….
(9) Line 152-153: Revise sentence structure and correct typo “times different portions”
(10) Line 170: Correct me if I’m wrong, but it seems that your Qe equation is incorrect. The units don’t work… I think it should be Qe = [Co-Ce]*(V)/m (see REF Q. Sun, et al, Water Research 37 (2003) pp 1535-1544. Also, add this reference into your manuscript when introducing this equation and your method.
(11) Line 173: Because there are lots of “models” to choose from, please state why you used the Sips Isotherm Model. Is it most appropriate for your kinds of samples? Why? Also, add an original Reference for this equation/model.
(12) Line 199: See comment #10 above…is this equation right or flipped?
(13) Line 214-215: Reword this title. “Electric properties” doesn’t sound right. Consider “Electrical Conductivity of Composite Materials”. Also, you were measuring “current” as a function of “applied potential”. Delete “current” in Line 215 and replace with “applied potential”.
(14) Line 214: State in this section what R.H. you used for the conductivity measurements.
(15) Line 232: Typo. “13C solids……”
(16) Line 246: Label C3 in Figure 2a…it is apparent in the bottom spectra as a left-shoulder…
(17) Line 270: It is helpful here to state some of the stretches (i.e, N-H stretches at XXX cm-1, etc etc) for chitosan….same comment for the PANI. Not all of them, but some would be helpful to guide the reader’s eye when looking at Figure 3.
(18) Line 272: I disagree. Your ATR-FTIR data indicates no significant differences in peak position (wavenumber) for the PANI alone compared to the PANI within chitosan composites. The fact that you barely see PANI peaks in the higher concentration CHT samples (particularly when 70wt% PVA is added) is likely just due to the other components in the composites dominating the IR absorption. This is very common in ATR-FTIR of samples with strongly absorbing bands that are co-located. (I’ve seen it myself in many cellulose and chitosan composites ATR-FTIR spectra). Don’t overinterpret the data here. Recommend deleting the conclusion in Line 272. Or just state that “while ATR-FTIR doesn’t clearly indicate chemical interactions between composite components, H-bonding between the PANI and the CHT is the most-likely intermolecular force present”.
(19) Line 282: Can you please put the TGA controls (i.e., pyrolysis in N2 of just CHT, PANI, and PVA) as a figure in the SI?
(20) Line 297: In Figure 4b (DSC data), can you state “exo up” on the “y-axis” (or in the Figure caption…whatever is easier.
(21) Line 302: Typo. Incorrect Figure reference. I think you mean Figure 4b.
(22) Section 3.4 “Swelling tests”. Can you clarify in this section what “doped” vs “undoped” means? This was lost on me while reading this section. Your results/discussion in this section could be strengthened by explaining that some more.
(23) Line 332: Are you discussing “doped” or “undoped” data? Not clear? And I don’t see the trend. Clarify.
(24) Line 335: To me, there doesn’t seem to be a trend. You say “In general, the swelling of samples adopt trends, where greater CHT and PVA content yield greater swelling…..” I see ½ of the samples (comparing apples to apples) increase and ½ of the samples decrease (i.e., for constant CHT and different PVA amounts, in the “undoped samples” PVA 50 is lower than PVA70 in CHT25 and CHT75, but PVA50 is higher than PVA70 in CHT50”. The trends are also questionable in the doped samples….. Please address this in your re-write of this section. If there is no significant trend with some experimental variables, then just state that. It indicates that there in minor impact from on the swelling from that variable.
(25) Line 355: Typo. Incorrect Figure reference. I think you mean Figure 5a.
(26) 373-374: Please clarify specifically what you mean by “geometric volume determination” (as written in the SI for Table S4). Did you physically measure the sample “volume” with something? What is the error of that measurement? (micrometer? Optical microscopy? ) How would the error in this measurement (which seems like it could be high) impact your “experimentally determined density” values? Your argument (which is interesting) re: differences in expt. Density and theoretical density could be stronger if you address this clearly up front.
(27) Line 380: This conclusion needs to remain “soft”…see comment (26) above….however if you address the “geometric volume” measurement, I think your conclusion can be stonger.
(28) Lines 431-446: Very interesting and well done. Nicest part of the manuscript that I’ve read so far. Well done here.
(29) Lines 454-457: Don’t just state the facts in Table 5. Please draw a conclusion from them. What does the data suggest?
(30) Lines 461-493: See comment (28) above. Well written. Nice job here.
(31) Line 500: Need to fix format. Add as section 3.7, and italicize.
(32) Line 538: Update as section 3.8 (see comment (31)).
(33) Line 574: Typo? “In general, the loss….” Doesn’t make sense as written.
(34) 586-588: I disagree with concluding that your data shows chemical interaction between CHT and PANI. Your make the argument in the manuscript that the 13C nmr shows no significant chemical interactions and the ATR-FTIR data are inclusive (as I would expect them to be based on my experience working with similar materials). Delete the 2nd and 3rd sentences as written and reword based on my recommendations in the .pdf of the edited document. “NMR and IR spectroscopy confirmed the presence of each component, and infer that cross-linking occurs between……”
(35) Table S6 (in supporting information): For clarity, recommend add a “space” between the label and the word “doped”.
Comments for author File: 
Comments.pdf
Author Response
Author Response to Reviewer Comments on MS ID jcs-696402
Reviewer #1
General Comment: Major Revision Required. This manuscript is quite interesting, and has some very good results and conclusions. I do not think further experiments should be necessary but the manuscript does require significant attention before I would consider it for publishing. Some areas are lacking in substance, need further clarification, and require more thought put toward conclusions, however. I believe the study will be improved and ready to publish after the authors consider and address each of the following discrepancies.
(1) Line 31: Is “manifold” a typo? Do you mean “multitude” or some other descriptor?
Response: The phrasing was changed to “multitude of”.
(2) Lines 43-44: How are “blending” and “preparation of composites” methods of “functionalization”. When I read “functionalization”, I think you mean “chemical modification”. Request you clarify this sentence by describing these some methods as “non-covalent” and some as “covalent” (i.e., grafting would likely be a covalent approach to making polymer composites”). In fact, I think you’re data strongly suggests these composites are “non-covalently modified”. It makes chemical sense that the PANI and CHT will hydrogen-bond with each other, though your data doesn’t clearly show that….almost no good characterization method will clearly indicate that with bulk composites (in my experience with silanized cellulose for example).
Response: Deleted “blending” and “preparation of composites”. Added “noncovalent cross-linking” and “via composite formation”. The references were changed accordingly.
(3) Lines 48-51: Poor sentence structure. The sentence starting with “Thus…” (line 48) isn’t a complete sentence… The sentence starting with “For example…” (line 49) needs to be reworded (see .pdf of written comments for suggested re-write).
Response: Appropriate revisions were made to address the reviewer comments.
(4) Line 74: Reword. Poorly structured sentence.
Response: Appropriate revisions were made to address the reviewer comments.
(5) Lines 75-79: This paragraph (concerning PVA) just hangs out there. Very poor transition “in” and “out” of the paragraph. Need to discuss “why” would you even consider using PVA in these kinds of composites? (i.e., what do they lack that PVA provides, etc etc).
Response: Transitions were added to sentences before and after.
(6) Line 95: Place period at end of 98%, capitalize “Sulfuric acid” and treat as a separate sentence, which would be in rhythm with the rest of your “materials” section.
Response: Appropriate edits were made to address the reviewer comments.
(7) Lines 100-106: Just delete this section and roll it in with the following section. It primarily describes “preparation of polymer composites” and not “shorthand notation” anyway…. You can put the “shorthand notation” description (which I like and I think IS important) as the last 2 sentences of the section 2.2 (Preparation of Polymer Composites) section.
Response: Probably even better to leave the shorthand notation section with only one sentence which refers to SI file. In this case shorthand notations can be clearly distinguished and not lost in the bulk of text. Other sentences have been unified with the Section 2.3.
(8) Line 111: Please state how much (wt%?, mol%, etc) of APS added….
Response: The recommended edits were applied.
(9) Line 152-153: Revise sentence structure and correct typo “times different portions”
Response: The recommended edit was applied.
(10) Line 170: Correct me if I’m wrong, but it seems that your Qe equation is incorrect. The units don’t work… I think it should be Qe = [Co-Ce]*(V)/m (see REF Q. Sun, et al, Water Research 37 (2003) pp 1535-1544. Also, add this reference into your manuscript when introducing this equation and your method.
Response: The equation has been corrected, where it should be noted that this was a typographical error, where the primary calculations used the correct equation. The appropriate Reference was inserted.
(11) Line 173: Because there are lots of “models” to choose from, please state why you used the Sips Isotherm Model. Is it most appropriate for your kinds of samples? Why? Also, add an original Reference for this equation/model.
Response: The Sips model was chosen based on the goodness of the best-fit curve fitting results and the utility of its fit parameters. A few introductory sentences with appropriate references were added.
(12) Line 199: See comment #10 above…is this equation right or flipped?
Response: The equation in question contains a typographical error and it has been corrected.
(13) Line 214-215: Reword this title. “Electric properties” doesn’t sound right. Consider “Electrical Conductivity of Composite Materials”. Also, you were measuring “current” as a function of “applied potential”. Delete “current” in Line 215 and replace with “applied potential”.
Response: The recommended edit was applied.
(14) Line 214: State in this section what R.H. you used for the conductivity measurements.
Response: The recommended edit was applied.
(15) Line 232: Typo. “13C solids……”
Response: The recommended edit was applied.
(16) Line 246: Label C3 in Figure 2a…it is apparent in the bottom spectra as a left-shoulder…
Response: Marked (as a right shoulder, left is C4).
(17) Line 270: It is helpful here to state some of the stretches (i.e, N-H stretches at XXX cm-1, etc etc) for chitosan….same comment for the PANI. Not all of them, but some would be helpful to guide the reader’s eye when looking at Figure 3.
Response: The recommended edits were applied.
(18) Line 272: I disagree. Your ATR-FTIR data indicates no significant differences in peak position (wavenumber) for the PANI alone compared to the PANI within chitosan composites. The fact that you barely see PANI peaks in the higher concentration CHT samples (particularly when 70wt% PVA is added) is likely just due to the other components in the composites dominating the IR absorption. This is very common in ATR-FTIR of samples with strongly absorbing bands that are co-located. (I’ve seen it myself in many cellulose and chitosan composites ATR-FTIR spectra). Don’t over interpret the data here. Recommend deleting the conclusion in Line 272. Or just state that “while ATR-FTIR doesn’t clearly indicate chemical interactions between composite components, H-bonding between the PANI and the CHT is the most-likely intermolecular force present”.
Response: The reviewer is correct and the recommended edits were applied.
(19) Line 282: Can you please put the TGA controls (i.e., pyrolysis in N2 of just CHT, PANI, and PVA) as a figure in the SI?
Response: Figure S3 was added to the SI. The numeration was changed accordingly.
(20) Line 297: In Figure 4b (DSC data), can you state “exo up” on the “y-axis” (or in the Figure caption…whatever is easier.
Response: The following annotation was added, “↓ endo down” in the caption.
(21) Line 302: Typo. Incorrect Figure reference. I think you mean Figure 4b.
Response: The recommended edits were applied.
(22) Section 3.4 “Swelling tests”. Can you clarify in this section what “doped” vs “undoped” means? This was lost on me while reading this section. Your results/discussion in this section could be strengthened by explaining that some more.
Response: Further edits and clarification were applied as recommended.
(23) Line 332: Are you discussing “doped” or “undoped” data? Not clear? And I don’t see the trend. Clarify.
Response: This is for undoped data. In particular, 129 vs 97% relate to water swelling. The overall trend is that “more CHT – higher swelling”, but the above two estimates do not fall into this trend, as denoted by the use of the term phenomenon in the revised manuscipt.
(24) Line 335: To me, there doesn’t seem to be a trend. You say “In general, the swelling of samples adopt trends, where greater CHT and PVA content yield greater swelling…..” I see ½ of the samples (comparing apples to apples) increase and ½ of the samples decrease (i.e., for constant CHT and different PVA amounts, in the “undoped samples” PVA 50 is lower than PVA70 in CHT25 and CHT75, but PVA50 is higher than PVA70 in CHT50”. The trends are also questionable in the doped samples….. Please address this in your re-write of this section. If there is no significant trend with some experimental variables, then just state that. It indicates that there in minor impact from on the swelling from that variable.
Response: We have addressed the reviewer query in the body of this section.
(25) Line 355: Typo. Incorrect Figure reference. I think you mean Figure 5a.
Response: The recommended edit was applied.
(26) 373-374: Please clarify specifically what you mean by “geometric volume determination” (as written in the SI for Table S4). Did you physically measure the sample “volume” with something? What is the error of that measurement? (micrometer? Optical microscopy?) How would the error in this measurement (which seems like it could be high) impact your “experimentally determined density” values? Your argument (which is interesting) re: differences in expt. Density and theoretical density could be stronger if you address this clearly up front.
Response: Dimensions were measured by digital caliper with 0.01 mm resolution. However, the random errors of the series of 15 measurements are anyways higher (~ 10 times) relate to the main error contribution.
(27) Line 380: This conclusion needs to remain “soft”…see comment (26) above….however if you address the “geometric volume” measurement, I think your conclusion can be stronger.
Response: The “geometric volume measurement” was addressed so the conclusion was not changed.
(28) Lines 431-446: Very interesting and well done. Nicest part of the manuscript that I’ve read so far. Well done here.
Response: Thank you for the constructive comment.
(29) Lines 454-457: Don’t just state the facts in Table 5. Please draw a conclusion from them. What does the data suggest?
Response: The data suggest the similar trend both for kinetics and equilibrium adsorption, which is already mentioned in this passage. Additional discussion on the matter of PSO vs PFO models was added.
(30) Lines 461-493: See comment (28) above. Well written. Nice job here.
Response: We appreciate the constructive comments by the reviewer.
(31) Line 500: Need to fix format. Add as section 3.7, and italicize.
Response: The recommended edit was applied.
(32) Line 538: Update as section 3.8 (see comment (31)).
Response: The recommended edit was applied.
(33) Line 574: Typo? “In general, the loss….” Doesn’t make sense as written.
Response: In general, the loss tangent factor is inversely proportional to the storage modulus. What is wrong here? This means that , that is true, because . Loss tangent factor and tanδ represent the same proportionality.
For Dynamic Mechanical Analysis (DMA), the loss tangent is read as one phrase, not two separate words. The ‘loss tangent’ is a key parameter in DMA and measures damping of a material. Its value will convey how well a material is at absorbing energy. A high value suggests the composite material has a high potential to dissipate energy, while a low value suggests the material will store the energy causing the material to have a more elastic response.
(34) 586-588: I disagree with concluding that your data shows chemical interaction between CHT and PANI. Your make the argument in the manuscript that the 13C nmr shows no significant chemical interactions and the ATR-FTIR data are inclusive (as I would expect them to be based on my experience working with similar materials). Delete the 2nd and 3rd sentences as written and reword based on my recommendations in the .pdf of the edited document. “NMR and IR spectroscopy confirmed the presence of each component, and infer that cross-linking occurs between……”
Response: The recommended edit was applied.
(35) Table S6 (in supporting information): For clarity, recommend add a “space” between the label and the word “doped”.
Response: The recommended edit was applied.
General Comments: The authors appreciate the constructive and insightful comments provided by reviewer #1. All recommendations have been addressed in the revised manuscript and further language editing for conciseness and clarity was applied throughout.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General Comments: The research of Anisimov et al. deals preparation and characterization of multicomponent biocomposites from polyaniline-chitosan-polyvinyl alcohol. It needs some minor work to bring it up to a standard for publication before to be accepted. My comments are as follows:
-How were the prepared composite samples conditioned before performing the analysis because it is hygroscopic and hydrophilic nature.
-Did authors perform the morphology study of the resulting composite samples to observe the dispersion of the PANI-chitosan in PVA.
- Literature values are not good to compare with our work because it may be different in composition, molecular weight, purity, etc. Therefore, thermal analysis (TGA and DSC) of the neat samples i.e., PVA and chitosan/PANI should be analysed and compared with the ternary composites in order to observe the differences in the thermograms.
-What is reusability of these composite materials for dye adsorption?
Author Response
Reviewer #2
General Comments: The research of Anisimov et al. deals preparation and characterization of multicomponent biocomposites from polyaniline-chitosan-polyvinyl alcohol. It needs some minor work to bring it up to a standard for publication before to be accepted. My comments are as follows:
-How were the prepared composite samples conditioned before performing the analysis because it is hygroscopic and hydrophilic nature.
Response: The samples were oven-dried at 600C for 24 h before performing moisture adsorption tests, as their mass depends on the ambient humidity. Humidity also slightly affects the conductivity of samples; however, the deviation of conductivity will create the same error throughout, because the hydrophilic constituent fraction is constant. The RH was equal 64% at that time. For dye adsorption tests, the samples were used with an ambient level of water uptake. For mechanical tests samples were preliminarily dried, same as for sample testing of moisture adsorption.
-Did authors perform the morphology study of the resulting composite samples to observe the dispersion of the PANI-chitosan in PVA.
Response: Detailed sample morphology was not reported herein since it was outside the scope of the present objectives. Such measurements will investigated at a later date when physicochemical properties need to be carefully correlated with sample morphology. Visual inspection of materials provided an assessment of sample homogeneity, whereas DSC results may also provide insight on the homogeneity of dispersion.
- Literature values are not good to compare with our work because it may be different in composition, molecular weight, purity, etc. Therefore, thermal analysis (TGA and DSC) of the neat samples i.e., PVA and chitosan/PANI should be analysed and compared with the ternary composites in order to observe the differences in the thermograms.
Response: The TGA profiles of the neat components were added in the SI file (Fig. S3). Regarding the DSC tests, they were mostly done to characterize the thermodynamic state of water in the sample films. Pristine CHT, PANI or PVA do not contain much water and therefore their DSC profiles are not very informative as a result. The retention of water for composites is generally much higher than that of single components (according to TGA results), where it is noted that prisitine CHT shows evidence of bound water.
-What is reusability of these composite materials for dye adsorption?
General Comments: The authors appreciate the constructive and insightful comments provided by reviewer #2. All recommendations have been addressed in the revised manuscript and further language editing for conciseness and clarity was comprehensively applied throughout.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors did a very good job on responding to my concerns addressed in the original submission. Particularly good job addressing my comments #18, #22, #24. And thank you (to the authors) for explaining in detail my question in comment #33 (one always learns something from the peer-review process if done well). I recommend the journal publish this Revision 1 of the manuscript.
