The Effect of the Degree of Polymerization and Polymer Composition on the Temperature Responsiveness of Cholesteric Semi-Interpenetrating Networks

Round 1

Reviewer 1 Report

The manuscript entitled „The effect of degree of polymerization and polymer composition on the temperature responsiveness of cholesteric semi-interpenetrating networks” is devoted to prepare and investigate the cholesteric liquid crystal oligomers in terms of their mesomorphic properties and selective reflection phenomenon. Presented results are interesting and give a new perspective on photonic materials with a strong redshift of the reflected color upon cooling. The topic of the manuscript fits well the scope of Crystals journal in the field of thermotropic liquid crystals. The manuscript contains novel results which should have impact on the specific field of research but also on the broader soft matter and liquid matter communities. I expect the manuscript will be appropriately cited if published. Despite of this I have several remarks which described in Comments to the authors. So, I recommend this paper for publication but after minor revision.

I expect to take into account the following remarks and questions:

(A) Please uniform the description of monomer 3 (in some place it is "Chiral dopant" in another one "chiral diacrylate monomer 3" or "Monomer 3") which increase clarity.

(B) In Figure 1, authors should provide the phase sequence and transition temperature for monomer 1 , 2 and 3.

(C) In Figure 2, authors should provide and comment the enthalpy of phase transition from DSC thermogram.

(D) In my opinion, in the y-axis of Figure 4, should be "Normalized reflection band shift" instead "Reflection band shift".

(E) In the last sentence of the Conclusion authors state that future tuning of the composition of final materials helps to use them in several applications. It would be valuable to describe more precisely what kind of tuning should be used. Maybe authors should consider new smectic monomers which have been synthesized recently (see e.g Journal of Molecular Liquids, Volume 271, 1 December 2018, Pages 353-360 and Journal of Molecular Liquids, Volume 331, 1 June 2021, 115723).

 

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript "The effect of degree of polymerization and polymer composition on the temperature responsiveness of cholesteric semi-interpenetrating networks" by Lansong Yue and co-authors presents investigation influence of the degree of polymerization (DP), smectic monomer additive and semi-interpenetrating network on the dependence of the helix pitch of cholesteric polymers on the temperature. The synthesized oligomers and polymers were studied by NMR and DSC methods. The temperature dependences of the helix pitch of cholesteric oligomers were obtained by measuring the spectral position of the selective reflection band.

 

The research was carried out at a good level, but there are a number of contradictions in the text that need to be resolved, as well as additional explanations should be added regarding the temperature dependence of the cholesteric helix pitch.

 

1. It is not clear from the text the choosing criterion the temperature intervals at which the temperature dependence of the cholesteric helix pitch was measured:

• For a sample without smectic monomer with DP=2.0, the cholesteric-isotropic phase transition temperature is T_c≅56 ºC (Figure 2a), but measurements of the spectral position of the selective reflection band (the cholesteric pitch) are made for temperatures of 62 ºC and 60 ºC (Figure 3a).

• For a sample without smectic monomer with DP=2.0, the cholesteric pitch was measured up to a temperature of T_min=25 ºC, which is far from the smectic-cholesteric phase transition temperature T_Sm≅9 ºC (Figure 3a, Figure 2a), while for the sample with DP=5.0, measurements were made up to T_min=20 ºC≅T_Sm≅19 ºC (Figure 3c, Figure 2a). A similar difference in temperatures Т_min and Т_Sm exists for the samples with smectic monomer additive ((Figure 3d, Figure 2b) and (Figure 3f, Figure 2b)).

 

2. Values of the relative band-shift at various temperatures (Figure 4) depend on the highest temperature T_max. What criterion was used to select the values of T_max?

 

3. What are the phase transition temperatures of oligomers with semi-IPN?

 

4. Why does the reflection band center shift to the short-wavelength region of the spectrum for oligomer with DP=2 and 3% IPN (Figure 4a)?

 

5. In samples with the smectic monomer additive, the initial position of the reflection band increases with an increase in DP, while for oligomers without smectic monomer, the initial position of the reflection band is least at DP=3.0. What, besides the temperature and the DP value, determines the spectral position of the center of the reflection band (the cholesteric helix pitch)?

 

6.

• Reflection band shift (y-axis in figure 4) is a dimensionless quantity.

• For reagent 2,2'-(ethylenedioxy)diethanethiol, the abbreviation EDDET is introduced in the text, but in Table 1 and Table 2 it is called as Dithiol. I think it will be more convenient for readers if the used designation in the text and Tables are the same.

• There are typos in the text of the manuscript. For example, «oC».

• Missing required data in section «Supplementary Materials».

 

 

I recommend the manuscript for publication in Crystals after major revision.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The comments have been fully answered.

I recommend the manuscript for publication in Crystals.