Polyurethanes Modified by Ionic Liquids and Their Applications
Round 1
Reviewer 1 Report
Line 47: The chemical structure of isocyanate and crosslinking degree can significantly affect the mechanical properties of PU. PU synthesized from aromatic isocyanate has high density, modulus, and tensile strength, but low elongation at break and impact resistance. By contrast, PU synthesized using aliphatic isocyanate has high elongation at break but low tensile strength. REMARK: The conclusions are not valid because the mechanical properties of polyurethanes depend not only on diisocyanates but also on polyols, chain extenders, crosslinking degree and phase separation. For example, commercial thermoplastic polyurethanes based on aromatic MDI are characterized by high elongation at break. Using aliphatic diisocyanates does not imply obligatory low tensile strength.
Line 71: The introduction of ILs into PU, polyvinyl chloride (PVC), polytetrafluoroethylene (PVDF), polyacrylates, and other polymer networks through simple physical mixing can endow the polymers with excellent properties. REMARK: Especially in the case of a review article one could expect references for each type of polymers.
Author Response
Line 47: The chemical structure of isocyanate and crosslinking degree can significantly affect the mechanical properties of PU. PU synthesized from aromatic isocyanate has high density, modulus, and tensile strength, but low elongation at break and impact resistance. By contrast, PU synthesized using aliphatic isocyanate has high elongation at break but low tensile strength. REMARK: The conclusions are not valid because the mechanical properties of polyurethanes depend not only on diisocyanates but also on polyols, chain extenders, crosslinking degree and phase separation. For example, commercial thermoplastic polyurethanes based on aromatic MDI are characterized by high elongation at break. Using aliphatic diisocyanates does not imply obligatory low tensile strength.
Answer: Thanks very much for your suggestion. It’s true that the mechanical properties of PU depend on all the reactants (including diisocyanates, polyols, and chain extenders) and the network structures of PU. The influence of diisocyanate structures on the mechanical properties of PU is not exactly as mentioned in the original manuscript. We have revised this part (line 34-65).
Line 71: The introduction of ILs into PU, polyvinyl chloride (PVC), polytetrafluoroethylene (PVDF), polyacrylates, and other polymer networks through simple physical mixing can endow the polymers with excellent properties. REMARK: Especially in the case of a review article one could expect references for each type of polymers.
Answer: Related references are added in this part (Ref. 45-60).
Reviewer 2 Report
Dear Authors, the review is well organized and written. Polyurethanes are a fascinating topic with countless applications growing day by day. The addition of ionic liquids is an aspect that has opened up new frontiers in this sector. I suggest these changes before the review is accepted.
1) Authors should re-write the abstract to summarize what is contained in the following discussion.
2) Introduction Line 21-24
References are necessary when Authors discuss general things
3) Introduction Line 25-28
References are necessary when Authors discuss general things
4) Introduction Line 29-31.
A list, possibly with a scheme and the relative structures of diisocyanated and chain extenders could be appropriate.
5) Introduction Line 34-35
“Due to the strong polarity of the hard segment, it is thermodynamically incompatible 34 with the nonpolar soft segment [4].”
This sentence should be discussed better. It is not clear for readers.
6) Introduction Line 45-50
References are necessary when Authors discuss general things
7) Introduction Line 50-51.
I suggest to add this recent and important references in the field:
- Felipe M. de Souza, Pawan K. Kahol, and Ram K. Gupta. Polyurethane Chemistry: Renewable Polyols and Isocyanates. , 1-24. DOI:10.1021/bk-2021-1380.ch001
- Maiuolo, L.; Olivito, F.; Ponte, F.; Algieri, V.; Tallarida, M.A.; Tursi, A.; Chidichimo, G.; Sicilia, E.; De Nino, A. A novel catalytic two-step process for the preparation of rigid polyurethane foams: Synthesis, mechanism and computational studies. React. Chem. Eng. 2021, 6, 1238.
8) 2.1. Physical blending of ILs with PU by solvent casting
The number of references cited is extremely poor.
9) 3. Applications of PU-IL
When Authors discuss general statements references are always necessary.
10) 3.5. Solid-state polymer electrolytes
I suggest reporting one or more examples of these kind of materials with the relative structures through a scheme.
11) 3.6. Flame retardant elastomers
I suggest reporting one or more examples of these kind of materials with the relative structures through a scheme.
12) 4. Conclusions
Conclusions must synthetically represent all the content of the review and any future implications. I suggest to re-write
Minor English editing required
Author Response
We thank all the reviewers for their careful review and encouraging comments. We have revised our manuscript according to the comments point by point and answered all the comments in the attached file. The revised parts of our manuscript are marked in blue.
Author Response File: 
Author Response.docx
Reviewer 3 Report
This manuscript is aimed at providing a review on polyurethanes (PURs) modified with ionic liquids. It is suggested to be accepted for opublication after some revision on the basis of comments below.
COMMENTS
1.
The title is proposed to be modified to the following:
Polyurethanes modified by ionic liquids and their applications
2.
For writing the name of polymers, using the IUPAC terminology is required. For instance, correctly poly(vinyl chloride) and not polyvinyl chloride (lines 71-72).
3.
In lines 70-71, the authors attempt to provide a short outlook related to polymers modified with ionic liquids by writing the following: “In terms of polymer modification, the ap-70 plication of ILs has received increasing attention”. However, no any references are provided. In the next few sentences, only poly(vinyl chloride), polytetrafluoroethylene, polyacrylates and other polymer networks are mentioned. In this respect, the authors are required to refer at least to the major related recent publications, such as:
He, B.; Peng, H.; Chen, Y.; Zhao, Q. High performance polyamide nanofiltration membranes enabled by surface modification of imidazolium ionic liquid. J. Membrane Sci. 2020, 608, 118202.
https://doi.org/10.1016/j.memsci.2020.118202
Kerscher, B.; Trotschler, T. M.; Pasztoi, B.; Groer, S.; Szabo, A.; Ivan, B.; Mulhaupt, R. Thermoresponsive polymer ionic liquids and nanostructured hydrogels based upon amphiphilic polyisobutylene-b-poly(2-ethyl-2-oxazoline) diblock copolymers.
Macromolecules 2019, 52, 3306-3318.
https://doi.org/10.1021/acs.macromol.9b00296
Sang, Y.; Huang, J. Benzimidazole-based hyper-cross-linked poly(ionic liquid)s for efficient CO2 capture and conversion. Chem. Eng. J. 2020, 385, 123973.
https://doi.org/10.1016/j.cej.2019.122107
Stumphauser, T.; Kasza, G.; Domjan, A.; Wacha, A.; Varga, Z.; Thomann, Y.; Thomann, R.; Pasztoi, B.; Trotschler, T.M.; Kerscher, B.; Mulhaupt, R.; Ivan, B. Nanoconfined Crosslinked Poly(ionic liquid)s with Unprecedented Selective Swelling Properties Obtained by Alkylation in Nanophase-Separated Poly(1-vinylimidazole)-l-poly(tetrahydrofuran) Conetworks. Polymers 2020, 12, 2292.
https://doi.org/10.3390/polym12102292
Yang, Y.; Guo, Y.; Gao, C.; North, M.; Yuan, J.; Xie, H.; Zheng, Q.
Fabrication of Carboxylic Acid and Imidazolium Ionic Liquid Functionalized Porous Cellulosic Materials for the Efficient Conversion of Carbon Dioxide into Cyclic Carbonates. ACS Sus. Chem. Eng. 2023, 11, 2634-2646.
https://doi.org/10.1021/acssuschemeng.2c06976
4.
In Figure 2, the meaning of the abbreviations in both Figure caption and the text should be provided.
5.
The title of Section 2.2 is not correct. The ILs are copolymerized with diisocyanate and phosphorus containing diol and not with PU, as shown in Figure 2. Therefore, the title of this Section should be changed. For instance, the following title would fit better to this Section:
Copolymerization of ILs with PU precursors
6.
Referring to ILs and polymers is not specific usually in the whole text. For instance, the authors write in line 351 that “an active IL with terminal hydroxyl group”. Then “polyols” and diisocyanate” is mentioned (line 356) without providing specific names of the used compounds. Although the authors refer to Figure 7, but this Figure does not provide any detail on the structure and composition of the “polyether-based polyol”. The authors are required to provide more specific details of such compounds, not only in lines 350-359, but in the whole manuscript as well.
Author Response
We thank all the reviewers for their careful review and encouraging comments. We have revised our manuscript according to the comments point by point and answered all the comments in the attached file. The revised parts of our manuscript are marked in blue.
Author Response File: Author Response.docx
