Preparation and Property of Bio-Polyimide/Halloysite Nanocomposite Based on 2,5-Furandicarboxylic Acid

Round 1

Reviewer 1 Report

The paper subject being  on posibility that 2,5-furandicarbxylic acoid could replace the oil-based material reducing the pollution and protecting the environment, is suitable for many journals including Journal Polymers and being interesting for many people.   The  suitable methodology is another merit of the paper, but paper organization is a demerit, the manuscript having nine figures and two tables.

before publication in my opinion is a need before publication a part of figures to have data in tables. Also the spectra of figures 2,3,and 5 have not peacks with values being difficult to be identified.                                                                                                    In the absence of moderate recommendation, my suggestion is minor revision

Author Response

Dear reviewer,

  Thank you very much for your good comments concerning our manuscript polymers-1405870 entitled “Preparation and property of bio-polyimide/halloysite nanocomposite based on the 2,5-furandicarboxylic acid”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. And here we revised our manuscript carefully, listed all the changes and marked in red in revised paper.  We appreciate for your warm work earnestly, and hope that the corrections will meet with approval.

 

 

Yours sincerely,

Shiwei Chen

 [email protected]

 

 

Response to Reviewer 1

 

Point 1: The paper subject being on possibility that 2,5-furandicarboxylic acid could replace the oil-based material reducing the pollution and protecting the environment, is suitable for many journals including Journal Polymers and being interesting for many people. The suitable methodology is another merit of the paper, but paper organization is a demerit, the manuscript having nine figures and two tables. Before publication in my opinion is a need before publication a part of figures to have data in tables. Also the spectra of figures 2,3,and 5 have not peaks with values being difficult to be identified.     

Response 1: Thank you very much for this suggestion. The suggestion is very useful for authors to understand the figures.

Fig. 2 XRD patterns of HNTs and m-HNTs

 

Fig. 3 FTIR spectra of HNTs and m-HNTs

 

Fig. 6 XRD patterns of PI, PI-HNTs-1%,PI-HNTs-3% and PI-HNTs-5%

 

Fig. 7 DSC of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

 

Fig.8 TGA(a) and DTG(b) curves of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

 

Table 2 The decomposition temperatures of the samples at 5 wt % and 10 wt % loss

                of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Samples	Temperature (°C) 10 wt % Loss
PI	390.1
PI-HNTs-1%	397.1
PI-PHNTs-1%	394.9
PI-HNTs-3%	399.0
PI-HNTs-5%	403.3

 

Table 3 The peak temperatures of the samples

of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Samples	Peak temperature (°C)
PI	596.9
PI-HNTs-1%	601.3
PI-HNTs-3%	603.5
PI-HNTs-5%	608.6

 

 

Once again, thank you very much for the excellent comments and suggestions.

 

Author Response File: Author Response.doc

Reviewer 2 Report

Please see attached file

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

  Thank you very much for your good comments concerning our manuscript polymers-1405870 entitled “Preparation and property of bio-polyimide/halloysite nanocomposite based on the 2,5-furandicarboxylic acid”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. And here we revised our manuscript carefully, listed all the changes and marked in red in revised paper.  We appreciate for your warm work earnestly, and hope that the corrections will meet with approval.

 

 

Yours sincerely,

Shiwei Chen

 [email protected]

 

 

Response to Reviewer 2

Point 1: First paragraph of introduction- Please rephrase and correct all grammatical errors.

Response 1: Thank you very much for this suggestion. We revised this paragraph as follows:

Polyimide (PI) is a particular kind of polymer，whose molecular chain contains imide ring. The molecular chain of PI has many aromatic rings and heterocycles. PI shows excellent thermal stability, flame retardant, high insulation, low dielectric constant and high mechanical properties [1-6]. Notably, PI has the best thermal stability among the polymers and exhibits excellent comprehensive properties in each application field. The film is one of the earliest PI products. It is widely used in aerospace, microelectronics, atomic energy, electrical insulation, liquid crystal display, membrane separation technology and other fields[7-11]. PI film is known as "gold film", and is the key to influence the technical development of the industry in many countries.

1. Lee, Y.J.; Huang, J.M.; Kuo, S.W.; Lu, J.S.; Chang, F.C. Polyimide and polyhedral oligomeric silsesquioxane nanocomposites for low-dielectric applications. Polymer 2005, 46, 173-181.
2. Zhu, B.K.; Xie, S.H.; Xu, Z.K.; Xu, Y.Y. Preparation and properties of the polyimide/multi-walled carbon nanotubes (mwnts) nanocomposites. Compos. Sci. Technol. 2006, 66, 548-554.
3. An, L.; Pan, Y.Z.; Shen, X.W.; Lu, H.B.; Yang, Y.L. Rod-like attapulgite/polyimide nanocomposites with simultaneously improved strength, toughness, thermal stability and related mechanisms. J. Mater. Chem. 2008, 18, 4928-4941.
4. Zhiping, S.; Hui, Z.; Yunhong, Z. Polyimides: Promising energy-storage materials. Angew. Chem. Int. Ed. 2010, 49, 8444-8448.
5. Cavallaro, G.; Lazzara, G.; Milioto, S. Dispersions of nanoclays of different shapes into aqueous and solid biopolymeric matrices. Extended physicochemical study. Langmuir the Acs Journal of Surfaces & Colloids 2011, 27, 1158-1167.
6. Guo, H.Q.; Meador, M.A.B.; McCorkle, L.; Quade, D.J.; Guo, J.A.; Hamilton, B.; Cakmak, M.; Sprowl, G. Polyimide aerogels cross-linked through amine functionalized polyoligomeric silsesquioxane. ACS Appl. Mat. Inter. 2011, 3, 546-552.
7. Luong, N.D.; Hippi, U.; Korhonen, J.T.; Soininen, A.J.; Ruokolainen, J.; Johansson, L.S.; Nam, J.D.; Sinh, L.H.; Seppala, J. Enhanced mechanical and electrical properties of polyimide film by graphene sheets via in situ polymerization. Polymer 2011, 52, 5237-5242.
8. Ha, H.W.; Choudhury, A.; Kamal, T.; Kim, D.H.; Park, S.Y. Effect of chemical modification of graphene on mechanical, electrical, and thermal properties of polyimide/graphene nanocomposites. ACS Appl. Mat. Inter. 2012, 4, 4623-4630.
9. Liaw, D.-J.; Wang, K.-L.; Huang, Y.-C.; Lee, K.-R.; Lai, J.-Y.; Ha, C.-S. Advanced polyimide materials: Syntheses, physical properties and applications. Prog. Polym. Sci. 2012, 37, 907-974.
10. Meador, M.A.; Malow, E.J.; Silva, R.; Wright, S.; Quade, D.; Vivod, S.L.; Guo, H.; Guo, J.; Cakmak, M. Mechanically strong, flexible polyimide aerogels cross-linked with aromatic triamine. Acs Appl Mater Interfaces 2012, 4, 536-544.
11. Wu, W.; Wang, K.; Zhan, M.S. Preparation and performance of polyimide-reinforced clay aerogel composites. Ind. Eng. Chem. Res. 2012, 51, 12821-12826.

Point 2: Example of grammatical errors- Line 16- The pristine HNTs were modified by the tetraethoxysilane (TEOS) and 4,4'-oxybisbenzenamine(ODA).

Response 2: We revised these grammatical errors in the article. For example, the revised sentence was as follows: The pristine HNTs were modified by tetraethoxysilane (TEOS) and 4,4'-oxybisbenzenamine(ODA).

Point 3: Line 41- Please provide some rationale and additional references for why

high temperature resistance is needed. The line is not self-explanatory.

Response 3: Recently, polyimide film was more widely available in high-tech field such as aeronautical and space area. These fields need high temperature resistance of the polyimide film. Meanwhile, we added some rationale and additional references in the revised article as follows:

Recently, polyimide film was more widely available in high-tech field such as aeronautical and space area. These fields need high temperature resistance of the polyimide film [12-14].

12. Chen, S.; Slattum, P.; Wang, C.; Zang, L. Self-assembly of perylene imide molecules into 1d nanostructures: Methods, morphologies, and applications. Chem Rev 2015, 115, 11967-11998.
13. Mittal, G.; Dhand, V.; Rhee, K.Y.; Park, S.-J.; Lee, W.R. A review on carbon nanotubes and graphene as fillers in reinforced polymer nanocomposites. Journal of Industrial and Engineering Chemistry 2015, 21, 11-25.
14. Yao, J.; Pantano, M.F.; Pugno, N.M.; Bastiaansen, C.W.M.; Peijs, T. High-performance electrospun co-polyimide nanofibers. Polymer 2015, 76, 105-112.

Point 4: In the introduction section please explain why you chose TEOS and ODA?There is no mention of why modification is needed on HNTs.

Response 4: Thank you very much for this useful suggestion. The suggestion is very important to improve our article. We explained the reasons and revised the article as follows:

In general, there are two crucial factors influencing the property of

polymer/HNTs nanocomposites: a good dispersion of HNTs in the polymer matrix and a desirable interfacial affinity between HNTs and the polymer. Because of the hydrophilic surface and the negatively charged external surface, it remains difficult to achieve a good dispersion of HNTs in the polymer matrix [24，33]. Scientists grafted coupling agents on the surface of HNTs to enhance the dispersion of HNTs in the polymer matrix and the interfacial interactions. In addition, Zhang used TEOS as silica precursor and silane as surface modifier to modify clay. They found that this silica shell on the surface of clay with many silanol groups greatly promoted silylation of clay[34].

24. Cheng, C.; Song, W.H.; Zhao, Q.; Zhang, H.L. Halloysite nanotubes in polymer science: Purification, characterization, modification and applications. Nanotechnology Reviews 2020, 9, 323-344.
25. Yuan, P.; Tan, D.Y.; Annabi-Bergaya, F. Properties and applications of halloysite nanotubes: Recent research advances and future prospects. Appl. Clay. Sci. 2015, 112, 75-93.
26. Zhang, Q.; Liu, Q.; Mark, J.E.; Noda, I. A novel biodegradable nanocomposite based on poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) and silylated kaolinite/silica core–shell nanoparticles. Appl. Clay. Sci. 2009, 46, 51-56.

Point 5: Line 56- Please check language.

Response 5: We check and revise the language. The revised article was as follows:

Carbon nanotube is an excellent additive in the composites. However, the price of the carbon nanotube is too expensive. In contrast, the price of HNTs is much cheaper than that of carbon nanotube. Thus, HNTs are a good substitute for carbon nanotube.

Point 6: Line 70-80- Please rephrase to convey your points clearly to explain advantages of HNT.

Response 6: We explain clearly the advantages of HNTs as follows:

HNTs are novel 1D natural nanomaterials with a unique combination of natural availability, large aspect ratio, rich functionality, tubular nanostructure, high mechanical strength, and good biocompatibility. These characteristics generate exceptional mechanical, thermal, and biological properties for HNTs-polymer nanocomposites at the low cost[15]. Therefore, HNTs could be used as good additives in high-performance polymer nanocomposites and multifunctional nanocomposites.

15. Yuan, P.; Tan, D.Y.; Annabi-Bergaya, F. Properties and applications of halloysite nanotubes: Recent research advances and future prospects. Appl. Clay. Sci. 2015, 112, 75-93.

Point 7: Line 128- Does all the DMAc evaporate at 60℃? From the TGA data it looks like some solvent is still present in the film.

Response 7: DMAc could not be evaporated entirely at 60℃. The solution was kept at 60℃ for a long time in order to get a polyimide film. When the film was obtained, the temperature was stepped curing (at each temperature of 100 °C, 200 °C, 250 °C and 300 °C for 1 h, respectively).

Point 8: Introduction does not clearly explain the objectives of the authors to make the modified HNTs. Please add some explanation. You can consider moving lines 300-313 to the introduction with more explanation on why each of the components was chosen?

Response 8: We explained the objectives to make the modified HNTs. The revised paragraph was shown as point 4 and 6.

Point 9: Line 170- Can you please add some references to support your statement that intensity reduction in XRD comes from surface coverage of HNTs. The lowered intensity could just be an artefact from sample preparation.

Response 9: According to the lilterature[16], the addition of methacrylic acid to ZnO could cause intensity reduction in XRD and the intensity of the diffraction peaks were consistently decreased with methacrylic acid loading.

16. Guo, B.C.; Lei, Y.D.; Chen, F.; Liu, X.L.; Du, M.L.; Jia, D.M. Styrene-butadiene rubber/halloysite nanotubes nanocomposites modified by methacrylic acid. Appl. Surf. Sci. 2008, 255, 2715-2722.

Point 10: Line 174- Are you suggesting that H bonds prevent exfoliation of the

structure of HNTs? Please clarify.

Response 10: According to the reference[17], its result indicates that most of the interlayer inner-surface AlOH groups of both halloysite and kaolinite were unavailable for grafting, since they were blocked by the strong hydrogen bonds between layers. We listed the reference in the article.

17. Yuan, P.; SOUTHON; Peter, D.; Liu, Z.; Malcolm, E.R.; James, M.; ANTILL. Functionalization of halloysite clay nanotubes by grafting with y-aminopropyltriethoxysilane. J. Phys. Chem. C 2008, 112, 15742-15751.

Point 11: Line 180-185- FTIR explanation needs to be clearer. Can you please have a table indicating the various bond stretches and explain differences in the spectrum for the two different types of samples. There is no obvious changes in the FTIR spectrum of the two samples.

Response 11: We made the clearer explanation as follows:

The broad peak of water OH stretch, centered at 3400 cm ^-1 , was further increased in the spectra of m-HNTs samples, which is attributed to the overlap with the NH₂ stretching vibration signal around 3400 cm^-1. Meanwhile, the peak at 1650 cm^-1 was ascribed to the O-H deformation of water. The peak intensity was also increased owing to the superposition with NH₂ deformation vibration signal around 1620 cm^-1.

Point 12: Line 197- The difference from Fig 4 between the two samples is not clear.

Response 12: The surface of m-HNTs in the Fig 4(a) was rough and obscure. We think this is due to the polyimide on the surface of HNTs. In contrast, the surface of pristine HNTs in the Fig4(b) was smooth and clean, showing that no polymer was covered on the surface.

Point 13: Please make some markings and explain more in detail why you state that Fig 4 (a) shows that the m-HNT’s are embedded?

Response 13: Compared to m-HNTs from Fig.4(b), the surface and edges of m-HNTs in the polyimide/HNTs was more obscure and rough. We think this is attributed to the polymer matrix covered on the surface. In addition, we made the difference between the Fig.5(a) and Fig.5(b) and found that the interfaces within polyimide/HNTs film and polyimide/m-HNTs film was different.  

  In order to make the sentence clear and accurate, we revised the paragraph again as follows:

Figure 5 showed the SEM images of PI-HNTs-1%(a) , PI-PHNTs-1%(b), PI-HNTs-3%(c) and PI-HNTs-5%(d). According to the figure, the surface of m-HNTs in the PI-HNTs-1% was much obscurer and rougher than that of HNTs in the PI-PHNTs-1%. This is attributed to the polymer matrix covered on the surface. In addition, interfaces between PI and m-HNTs within PI-HNTs-1% were obviously different from that between PI and HNTs within PI-PHNTs-1%.The interface between PI and HNTs within PI-PHNTs-1% was clear. The phenomenon displayed that m-HNTs had better compatibility with bio-based polyimide film. This result confirmed that the modification of HNTs was beneficial for the compatibility between HNTs and bio-based polyimide. The reason was that the amino of the m-HNTs could involve in the formation of hydrogen bond and have a chemical reaction with bio-based polyimide film. According to figure 5(c) PI-HNTs-3% and 5(d) PI-HNTs-5%, more HNTs aggregated to big particles with the increase of HNTs.

Point 14: Lines 197-204- Please improve English.

Response 14: We revised our article. The result could be seen from Point 14.

Point 15: In Fig-6- Typical step pattern of Tg not seen in this graph. Can you please provide some explanation for this? Please also provide wider temperature DSC data and compare the modified and pristine membranes.

Response 15: According to this useful suggestion, we showed Tg in the graph and provide wider temperature as follows：

Fig. 7 DSC of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Figure 7 showed DSC of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%. As seen from the figure, Tg of PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5% was 313.4°C, 311.8°C and 312.6°C, which was larger than 309.8°C of PI.

Point 16: Fig 7- Please quantify data from the DTA plots. Please tabulate the data for easier understanding. I don’t believe that the temperature has increased significantly with addition of m-HNTs?

Response 16: Thank you very much for this suggestion. In order to understand the thermal stability for authors, we tabulate the data from Fig.8 as follows:

 Table 2 The decomposition temperatures of the samples at 5 wt % and 10 wt % loss

             of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Samples	Temperature (°C) 10 wt % Loss
PI	390.1
PI-HNTs-1%	397.1
PI-PHNTs-1%	394.9
PI-HNTs-3%	399.0
PI-HNTs-5%	403.3

  It could be seen from table 2 that the temperatures at 10wt% loss of PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5% were 397.1°C, 399.0°C, and 403.3°C, which were higher than 390.1°C of PI.

Table 3 The peak temperatures of the samples

of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Samples	Peak temperature (°C)
PI	596.9
PI-HNTs-1%	601.3
PI-HNTs-3%	603.5
PI-HNTs-5%	608.6

  According to table 3, the peak temperatures on the DTG curves of the samples were 601.3°C, 603.5°C and 608.6°C, which were also larger than 596.9°C of PI. The peak temperature was ascribed to the largest decomposition rate of the polymer. So the result could show that the thermal stability of PI-HNTs increased compared to PI.

Point 17: In Fig.7- How does the pristine HNT impact the thermal properties? Please add that data to further highlight the advantages of modifying HNT’s.

Response 17: We added the data of PI-PHNTs-1% in the figure 8 and table 2. It could be seen that the pristine HNTs could also improve the thermal stability of PI. This is because: firstly, HNTs could slow down the escape of volatile products in the degradation process due to barrier; secondly, volatile products may be entrapped into the lumen of Hal, causing an effective delay of mass transport and, as a consequence, increased thermal stability entrapment effects. Meanwhile, the temperature 10 wt% loss of PI-PHNTs-1% was lower than that of PI-HNTs-1%, showing that m-HNTs could improve the thermal stability of the PI more efficiently than pristine HNTs. The better thermal stability is attributed to the barrier effect of the finely dispersed particles which hindered the diffusion of small molecules generated during the thermal decomposition.

 

Fig.8 TGA(left) and local enlarged image (right) curves of PI, PI-HNTs-1%, PI-HNTs-3% and PI-HNTs-5%

Table 2 The decomposition temperatures of the samples at 10 wt % loss

Samples	Temperature (°C) 10 wt % Loss
PI	390.1
PI-HNTs-1%	397.1
PI-PHNTs-1%	394.9
PI-HNTs-3%	399.0
PI-HNTs-5%	403.3

Point 18: Why is there such a high initial weight loss for the membranes in TGA plot?

Response 18: The first mass loss procedure ranged from 100℃ to 200℃ corresponding to small ODA and TEOS volatilization, which attached to polyimide and HNTs.

Point 19: Fig 8- The explanation on why ODA improves the moisture resistance is not clear. Please provide some chemical mechanism to support your conclusions.

Response 19: It is reported that OH groups on the halloystie was hydrophilic and the interface defect could easily occur between the polyimide film and halloysite, resulting in the water absorption of PI-PHNTs-1% was higher than pure bio-based PI film. HNTs surface modification with ODA could improve the dispersion level of clay mineral particles in the polymer matrix. The cross-linked network could be formed upon oligomerization of ODA and grafting reactions that prohibited the formation of agglomerated structures. Meanwhile, the network increased the compatibility between HNTs and polyimide matrix. Thus the network could effectively reduce the defect interface. Finally, the water resistance was improved.

Point 20: Fig 8- Please compare your data with some other data from literature to highlight the difference between this improvement and what is known from

literature.

Response 20: We compared our result with other literature[18]. Their study also confirmed that the nanoclay could improve the water resistance of the polymer and   they suggested that the properties of the polymer/clay nanocomposite strongly depended on the degree of the dispersion of the nanoclay in the polymer matrix.

18. Sun, Q.; Schork, F.J.; Deng, Y. Water-based polymer/clay nanocomposite suspension for improving water and moisture barrier in coating. Compos. Sci. Technol. 2007, 67, 1823-1829.

Point 21: It is still not clear to me why there is so much agglomeration with 3% and 5% m-HNTS? Can you please add some characterization data to indicate the

agglomeration? SEM on the dispersion and the films will be a good addition

to support your conclusions.

Response 21: We added the SEM images according to this useful suggestion and revised the article as follows:

 According to figure 5(c) PI-HNTs-3% and (d) PI-HNTs-5%, more HNTs aggregated to big particles with the increase of HNTs.

Point 22: Is there any difference in agglomeration between the pristine and modifies m-HNTs

Response 22:

 

  We compared SEM images of pristine and modified HNTs in the polyimide with 3 wt%. It could be seen from PI-PHNTs-3% (e) that it is easier for the pristine HNTs to agglomerate. In contrast, the m-HNTs had better dispersion in the polymer matrix according to (c) PI-HNTs-3%.

Point 23: Section 3.3 needs to be modified/rewritten and moved to introduction.

Response 23: Based on the suggestion from 4,6 and 8, we made the corresponding revision in the introduction of the article. The revised paragraph was shown as point 4, 6 and 8. Here, we modified 3,3 and moved to 3.1. We thought it was easier for readers to comprehend the article.

The scheme to prepare bio-based polyimide/HNTs nanocomposite was illustrated in Fig.1. Owing to the hydrolysis of TEOS, more OH groups were covered the surface of the HNTs. These OH groups could have the chemical or physical interaction with the NH₂ groups of the ODA.  TEOS made ODA modify the HNTs more efficiently. BTDA could have pre-polycondensation reaction with bio-based diamine to obtain linear polyamic acid. When the temperature went up to 150 °C, polyamic acid could have cross-linking reaction to obtain ring polyimide. Due to the polar groups, m-HNTs could have the chemical or physical interaction with the polyimide. Thus, the compatibility and interfacial interaction between m-HNTs and polyimide matrix was improved, leading to strong structural stability and effective stress transfer. Finally, the improved tensile strength and Young’s modulus of bio-based PI/HNTs nanocomposite film could be expected compared to that of pure bio-based PI. 

 

Once again, thank you very much for the excellent comments and suggestions.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,

I would suggest having the manuscript proof read by a native english language speaker/ use a service to polish the overall language of the manuscript.