Development of Biodegradable Polyesters: Study of Variations in Their Morphological and Thermal Properties through Changes in Composition of Alkyl-Substituted (ε-DL) and Non-Substituted (ε-CL, EB, L-LA) Monomers

Round 1

Reviewer 1 Report

see attached file

Comments for author File: Comments.docx

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript entitled “Development of biodegradable polyesters: study of variations in their morphological and thermal properties through changes in composition of alkyl-substituted (ε-DL) and non-substituted (ε-CL, EB, L-LA) monomers” by Jesús-Téllez, López-González et al., is an interesting piece of work in the field of the development of new biodegradable polyester materials, particularly the combinations of ε-caprolactone (ε-CL), ethylene brassylate (EB), L-Lactide (LLA) with the alkyl substituted lactone ε-decalactone (ε-DL).

The results seem to be accurately presented and the bibliography fairly updated. However, the manuscript needs significant English editing.

There is no doubt that the new materials produced have been fully studied and characterized by employing different techniques such as ¹H NMR experiments, GPC and DSC measurements as well as XRD analysis.

 In my opinion, the work is suitable for publication after consideration of the following suggestions:

·       In the introduction, line 79, authors introduce the benefits in the implementation of stannous octoate and bismuth salts as catalyst in the synthesis of PLLA, PDL and L-lactide/ε-decalactone copolymers, in terms of high molar masses. However, these systems are quite toxic, and authors should alert on that in this section.

·       Also in this section, authors describe several benefits in the use of metal-free catalysts, as a greener and low-cost alternative to the organometallic species. However, authors forget to mention the catalyst loadings that organo-catalysts commonly need to be efficient in this process (5 mol%, which is very high in comparison with metal-based catalyst systems) as well as the reaction temperature (100 ºC in this case, very high as well). Authors should clarify these questions when referring to them.

·       In this case, the ROP of the polar monomers is carried out by the sequential addition of monomers. This is an important weak-point in the article, since it is much more interesting to have a one-pot catalytic reaction, with both monomers present in the pool from the beginning. Have the authors made any progress in this question?

·       Another weakness in the results is the loss of steroregularity in the copolymers when using L-LA. This is quite disappointing result since this fact produces an important loss of crystallinity in the materials produced. Have the authors reduced the reaction temperature in order to avoid the lack of stereoregularity in L-LA?

·       Finally, authors claim: “It should be noted that some of these copolymers will be exposed to hydrolytic degradation conditions and posteriorly, applied in the development of soft medical devices.”. In my opinion, author should come with convincing experimental evidences before claiming not proven experimental hypotheses.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper submitted by Robles-Gonzales et al. investigates the synthesis and the physicochemical characterization of three series of polyesters block copolymers. 

The paper is clear, well written and the conclusions are supported by the results. However, some corrections are needed before its publication:

1. from both abstract and conclusion sections it can be supposed that the authors have investigated also the hydrolytic degradation of the copolymer samples. the authors must modify these section in order to avoid any misunderstanding.

2. the introduction section must be completed with several  very new references concerning the synthesis of biodegradable copolymers based on polyesters. some suggestions can be: https://doi.org/10.1039/D2PY00620K; https://doi.org/10.3390/polym14183736; https://doi.org/10.1038/s41467-022-30220-y; https://doi.org/10.1002/pi.6085

3. the authors state in the introduction section that the polycondensation leads to high dispersities of the copolymers but their values are also quite high. they must discuss the evolution of the dispersity as a function of the copolymer composition. moreover, the SEC chromatograms provided in fig 5 show that there are some samples with have a shoulder which indicates the presence of two populations.

4. complete the caption of fig 6 by indicating which figures correspond to heating and which to cooling.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I satisfied with the corrections made by authors, I think manuscript can be accepted for  publication now.

Reviewer 2 Report

The manuscript entitled “Development of biodegradable polyesters: study of variations in their morphological and thermal properties through changes in composition of alkyl-substituted (ε-DL) and non-substituted (ε-CL, EB, L-LA) monomers” by Jesús-Téllez, López-González et al., has been clearly improved attending to the referees’ comments.

 

For this reason, I recommend publication for this work in Polymers in its current form.