Synthesis of High Molecular Weight Vinylphenyl-Con Taining MQ Silicone Resin via Hydrosilylation Reaction

Round 1

Reviewer 1 Report

I'm satisfied with the amendments introduced to the manuscript and now can recommend its publication in Coatings.

Reviewer 2 Report

Authors has adequately answered to the reviewers requests and corrected some important errors. The quality of the paper has thus been improved and the paper is now suitable for publication in Coatings.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This ms reports on the synthesis and characterization of new so-called MQ silicone resins. MQ resins are synthetized by combining tetra- and monofunctional entities. Here it is proposed to combine difunctional entities in a second step to build a 3D network of high molecular weight. The final molecular weight can be tuned by adjusting the frcation of reactive vinyl groups in the precursor resins. This is an interesting system and the synthesis is fairly well described. However I have some concerns which make this ms unsuitable for publication in its actual state. First, the ms must be reviewed by a native or proficient English speaker. The syntax is chaotic. The ms is generally hard to follow. Besides this language problem, I have further concerns.

Figure 1. Please clarify and make the notations coherent. Replace VPSS by VPMQ.

Generally speaking, the figures are much too small.

Figure 5 is probably wrong. Tg should correspond to a Cp jump, not to a heat flow peak. Besides I strongly doubt VPMQ-4 sample may exhibit a melting peak. Why should this particular sample crystallize? The legend in the graph is not consistent with the text (VPMQ-4 vs VPMQ-5).

Reviewer 2 Report

The idea to employ hydrosilylation of MQ-type silicone resin containing dimethylvinylsilyl groups for the synthesis of high molecular weight silicone resins to overcome the limitations of conventional (hydrolysis and condensation based) methods is reasonable. Nevertheless submitted manuscript is not suitable for publication in its present form and several issues pointed below should be improved prior to its publication in my opinion.

The characteristic (¹H, ²⁹Si, FT-IR, GPC, TG an DSC) of poly(diphenyl)siloxane used as one of the starting materials should be provided. The structure of VMQ resin in Figure 1 is presented in a simplified and idealized form which can be misinterpreted by the reader as octasilsesquioxane structure. This should be clarified eg. like in the review by A. Muzafarov et al (Molecules 2017,22, 1768) cited as ref [15]. Figures presenting ¹H, ²⁹Si NMR and FT-IR spectra, as well as DSC curves, are of pure quality. The lines are too thick in my opinion which makes it impossible to be thoroughly analyzed and verified. On page 6, line 214, the authors write: …“In addition, the characteristic peak near 2 080-2 280 cm^-1 (Si-H group stretching) was not observed, indicating that the Si-H groups of PDPS were completely reacted away and without free PDPS in the reaction.”… Nevertheless, careful observation of ¹H NMR spectrum of VPQM resin presented in Figure 3b allows noticing minor line aberration near 4 ppm which could be attributed to the proton in Si-H bond, which in turn can prove the presence of unreacted polysiloxane in the measured sample. As pointed above higher quality spectra should be provided. On page 6, line 231, the authors write: …„This analysis indicates that VPMQ has been synthesized successfully through the addition reaction of Markownikow and Anti-Markovnikow[29].”… what is also reflected in the VPMQ resin structure given in Figure 3a. The presence of α and β adducts should result in the presence of additional signals on ²⁹Si NMR spectra of VPMQ resins what can’t be observed due to poor quality of supplied spectra. This should be improved and commented. The interpretation of DSC curves presented in Figure 5 is incorrect in my opinion. The glass transition results in a gradual transition that occurs over a range of temperatures in the plot of heat flow versus temperature due to the change in sample heat capacity while the “peak” in a plot of heat flow against temperature indicates sample crystallization which is an exothermic process. If the convention “exothermic – down” was used (it hasn’t been clearly pointed by authors) then signals present in the plot of heat flow versus temperature (Figure 5.) in the range from -75 to -25°C should be attributed to the crystallization process and not the glass transition. The description given by authors on page 8, line 309: …“In addition, the Tm (50-240 °C) for VPMQ-5 was also detected by DSC, and melting transitions of the sample have been observed. The result showed that VPMQ-5 with a Tm of 87.5 °C and exothermal peak temperature of 144.6 °C, it can be attributed to formation of semi-solid macromolecule structure. Moreover, The total heat enthalpy (ΔH) of VPMQ-5 over the whole melting transition was measured by calculated from the melting peaks, and the ΔH of VPMQ-5 is 4.8 J/g.”… is also incorrect. Melting is an ENDothermic process not EXOthermic so the presence of this signal cannot be attributed to the melting process. The presence of this signal should be rather interpreted as an exothermic chemical reaction (eg. hydrosilylation of unreacted vinyl groups with remaining polysiloxane) at elevated temperature. This interpretation is in my opinion consistent with the observation given above in point 4.

Reviewer 3 Report

The paper submitted by Jianye Ji and co-workers presents a study on the synthesis of high molecular weight Vinylphenyl-MQ silicone resins through a hydrosilylation reaction. The novelty of the paper is difficult to establish due to a non-balanced and logically structured work.

Furthermore, the unclear target of the whole approach, the lack of extensive details about the experiments and the characterizations used, as well as a poor discussion of the results in the light of the international literature, lead to a very poor conclusion of the paper. Thus, advantages and novelty statement are weak and not properly argued. Owing to this important lacks, I do not recommend publication of this manuscript in the present form.