Preparation and Properties of UV and Aziridine Dual–Cured Polyurethane Acrylate Emulsion

Round 1

Reviewer 1 Report

Wang and coworkers have studied UV and aziridine dual crosslinkable polyurethane acrylate emulsion for generating wear and water resistant film. The optimal amount of aziridine crosslinker was 6% which provided enough mobility to perform the UV crosslinking to obtain tough film with best water resistivity. This work is interesting. Few concerns are given below   It is important to compare all the properties of the films (Tensile strength, hardness, water and wear resistivity) with only AZ cured film with Sac content of 6% (OS6). This is an important control experiment which explains the importance of dual crosslinking.  

In various experiments the author represented the data with error bars. However, it is important to explain how the error bars were calculated for each experiment. 

  The contact angle of the crosslinked matrix does not change with Sac content. This should be explained in terms of surface property which is similar for all the samples. 

Author Response

In the original manuscript, we only compared the properties of UV-cured and dual-cured films, but the performance of films only cured by aziridine was not included, because the UV initiated crosslinking of unsaturated double bonds was the main curing reaction. Without the crosslinking of unsaturated bonds, the reaction between Sac-100 (aziridine) and carboxylic groups in PU prepolymer can only lead to oligomers or branched macromolecules, in other words, the reaction of Sac-100 served as a role of icing on the cake. Nevertheless, we did supplementary experiments to verify our ideas, which were included in the Supplementary Material.

In response to the question about error bars, we have updated the experimental methods and result analyses in subsections 2.4 and 2.5 in the revised manuscript.

For the contact angle of the crosslinked matrix not changed with Sac content, we have renewed the explanations in lines 304-307: there is no obvious difference in short-time water contact angle due to the inward arrangement of hydrophilic groups.

Reviewer 2 Report

Wang et al. reported the synthesis and characterization techniques of waterborne polyurethane acrylate (PUA) emulsion in the following manuscript “Preparation and Properties of UV- and Aziridine- Dual-Cured 2 Polyurethane Acrylate Emulsion”. The manuscript is well written explaining the synthesis procedure and characterizations in detail.

The reviewer recommends the article to be accepted after the following corrections.

Comment 1: The authors should elaborate the possible application of waterborne polyurethane acrylate (PUA) emulsion in the Introduction section.

Comment 2: The authors are requested to provide the SEM image in 1 micrometer or 500 nm scale. Hence, the difference in morphology for various films can be better visualized. However, the 10 micrometer scale presently produced does not reveal the morphological changes.

 

Comment 3: The authors should clearly state the novelty of the work comparing the knowledge gap in literature. This section can be added as the last paragraph in “Results and Discussions” section.

Author Response

A1:

We have added the application of WPUA emulsion in Introduction (lines 28-32 and 35-40), which makes the study more meaningful and comprehensive.

A2:

In the orginal manuscript, the SEM magnification was ×2K times. In these days, we prepared the new samples and tried again to characterize the morphology of the tensile fracture surface with SEM. However, when the magnification was increased to ×20K, the SEM images became fuzzy and unclear. In fact, the tensile fracture surface was relatively rough, so it might be more advantageous to observe the fracture surface with a lower magnification. If the roughness were small enough, AFM observation would be a more effective method then SEM. Still, the new SEM images with ×20K magnification were also displayed  in the Supplementary Material (Figure S3) for reference.

A3：

A comparison table (Table 4) has been added at the end of the Results and Discussion. The differences in the performance of the materials and innovation  between this work and other studies are shown.

Reviewer 3 Report

Dear Dr.

 

I critically evaluated the article which entitled " Preparation and Properties of UV- and Aziridine- Dual-Cured 2 Polyurethane Acrylate Emulsion ". The topic is interesting and sounds well for readers of coatings.

You should improve the result section of abstract. Lines 6 to 16 should be summarized.

I would recommend approaching other keywords rather those used in title to increase the visibility through search by readers

You should add statistical analysis at the end of materials and methods. Also, significant letter should be added on the figures and tabled.

Table 1 and table 2 and table 3, standard division and significant letter should be added.

There was a lot of error in the figure name, axis title, units, ….

Quality of figures was very low

Different physicochemical properties such as moisture content, aw, density, thickness, color, solubility, .. should be evaluated.

Discussion of different parts seems introduction, lacks relation between feedings of studies and previous results; conclusions are not drawn appropriately.

Author Response

Many thanks for making helpful comments and suggestions, and we have taken all these comments and suggestions into account as follows.
1. The Abstract was condensed, significant characterization results and trends were added.
2. The keywords have been replaced with moderate words that are different with the headline.
3. A new subsection, subscetion 2.5, has been added to describe the method of significance analysis, and the significance letters have been marked in the relevant Tables and Figures.
4. All figures have been re-exported to obtain high-quality result.
5. The water content has been tested by rapid moisture balance analyzer, the result was included in Supplementary Material.
6. We try to improve the results and discussion part, but since the research content is not involved by predecessors, we are exploring its mechanism, and we will release the results if any.

Reviewer 4 Report

Comments

- Title need arrangement (repetition of and )

- Remove 1 from authors affiliations no 2 

- Abstract: ok add all the abbreviations in it 

- Keywords: ok (water and wear resistance)

- Introduction: add more references

- Results need more discussions

- References update 2022

Author Response

Thanks for comments and suggestion concerning, which are all valuable and very helpful for revising and improving our paper. We have studied comments carefully and have made correction. 
1. We carefully considered the title of the paper and made minor revision. The keywords were modified to improve the searchability;
2. The superscript used to indicate the author’s affiliation has been modified;
3. Abbreviations have been added in the abstract;
4. More references have been added and used for comparison between our work and other studies at the end of Results and Discussion;
5. More physical properties are in Supplementary Material;
6. No reference in 2022 related to this study was found, so we try our best to cite the latest important literature.

Round 2

Reviewer 1 Report

The authors answered the questions fairly well and performed the necessary experiments. I suggest accepting the manuscript without further change.

Reviewer 2 Report

The authors have adequately replied to the concerns. Hence the reviewer recommends the manuscript to be published.

Reviewer 3 Report

no