IP Library › Granted Patent US 12,365,764
Granted Patent B2
US 12,365,764 · App. 18/243,824 · Granted Jul 22, 2025

Fabrication of hydrophobic, mechanically flexible and optically transparent polyimide aerogels

Inventors: Hani Naguib (Toronto, CA); Omid Aghababaei Tafreshi (Toronto, CA); Shahriar Ghaffari-Mosanenzadeh (North York, CA); Zia Saadatnia (North York, CA)
Assignee: THE GOVERNING COUNCIL OF THE UNIVERSITY OF TORONTO
C08G73/1032C08J3/24C08J2379/08
View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 12,365,764
App. No.
18/243,824
Granted
Jul 22, 2025
Kind
B2
Abstract

The present disclosure provides a method of fabrication of physically crosslinked polyimide (PCPI) aerogels with significantly improved properties using no chemical crosslinker. The fabricated PCPI aerogels present high moisture resistance, hydrophobic behavior, ultralow density, ultrahigh porosity, excellent thermal stability, increased mechanical strength, and high mechanical flexibility. Also, samples have been successfully fabricated in a thin-film geometry with high mechanical flexibility and controlled thickness. Furthermore, some fabricated aerogel films present improved optical transparency of over 80%, which is the highest transparency reported so far for organic PI aerogels.

Claims (34)

1. A polyimide aerogel, comprising:

a polyimide-based polymer of the formula 1:

wherein n is an integer in a range between about 30 to about 50, and

wherein the polymer is physically crosslinked through polymer chain entanglement, and the aerogel is formed by a process including initial gelation for about 1-10 minutes; and

wherein the aerogel is free of polyamic amide polymer.

2. The polyimide aerogel according to claim 1 , wherein the aerogel has a pore size in a range from about 2 nanometers to about 100 nanometers.

3. The polyimide aerogel according to claim 1 , wherein the aerogel has pores with a pore size of less than about 2 nanometers.

4. The polyimide aerogel according to claim 1 , wherein the aerogel has a porosity in a range from about 85% to about 99%.

5. The polyimide aerogel according to claim 1 is free of chemical crosslinkers.

6. The polyimide aerogel according to claim 1 , wherein the aerogel has a density in a range from about 0.07 g/cm 3 to about 0.25 g/cm 3 .

7. The polyimide aerogel according to claim 1 , wherein the aerogel has a thermal conductivity in a range from about 15 to about 50 milliwatts/degrees Kelvin-meters.

8. The polyimide aerogel according to claim 1 , wherein the aerogel is characterized by a hydrophobicity in a range from about 90 degrees to about 140 degrees water contact angle.

9. The polyimide aerogel according to claim 1 , wherein the aerogel is characterized by a water uptake as low as about 1%.

10. The polyimide aerogel according to claim 1 , wherein the aerogel has an onset of thermal decomposition in a range from about 500 to about 700° C.

11. The polyimide aerogel according to claim 1 , wherein the aerogel has a dielectric constant in a range from about 1.5 to about 3.

12. The polyimide aerogel according to claim 1 , wherein the aerogel is in the form of a film having a thickness of at least about 80 microns, and wherein the aerogel has optical transparency in a range from about 60% to about 99%.

13. The polyimide aerogel according to claim 1 , wherein the aerogel is characterized by a compressive modulus in a range from about 17 to 25 Mega Pascal (MPa).

14. The polyimide aerogel according to claim 1 , wherein the aerogel is characterized by a tensile modulus in a range from about 1 to 5 Mega Pascal (MPa).

15. A process of making a polyimide aerogel of claim 1 , comprising the steps of

forming a wet gel by reacting a diamine monomer (DIAM) with a dianhydride monomer (DIAH) in a reaction solution comprising a dipolar aprotic solvent to form the polymer of Formula A; wherein n is between the range of 30 to 50

imidizing the formed polymer;

gelation of the formed polymer for about 1-10 minutes;

replacing the aprotic solvent with a drying solvent; and

removing the drying solvent from the formed wet gel.

16. The process of claim 15 , wherein the step of imidizing the formed polymer is performed through thermal imidization or chemical imidization.

17. The process of claim 15 , further comprising the step of aging the wet gel obtained by the initial gelation to increase the polymerization yield and to advance the degree of physical crosslinking.

18. The process of claim 15 , wherein the aprotic solvent is N-methylpyrrolidinone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or a mixture of NMP and tetrahydrofuran (THF).

19. The process of claim 15 , wherein the step of reacting the DIAM monomer with the DIAH monomer is done without the use of a chemical crosslinker.

20. The process of claim 15 , wherein the DIAM monomer and DIAH monomer are first dissolved separately then the DIAM monomer solution is combined with the DIAH monomer solution.

21. The process of claim 15 , wherein DIAM monomer is first dissolved and DIAH monomer is added to the DIAM solution.

22. The process of claim 15 , wherein the diamine monomer (DIAM) is 2,2′-dimethylbenzidine (DMBZ).

23. The process of claim 15 , wherein the dianhydride monomer (DIAH) is biphenyl-tetracarboxylic acid dianhydride (BPDA).

24. The process of claim 15 , wherein the drying solvent is removed via supercritical drying, freeze drying, or ambient pressure drying.

25. The process of claim 15 , wherein the wet gel forming step occurs over a period of time ranging between about 1 minute to about 24 hours.

Assignments (1)
NUNC PRO TUNC ASSIGNMENT Recorded May 13, 2024
From: NAGUIB, HANI; AGHABABAEI TAFRESHI, OMID; GHAFFARI-MOSANENZADEH, SHAHRIAR; SAADATNIA, ZIA
To: THE GOVERNING COUNCIL OF THE UNIVERSITY OF TORONTO
Reel/Frame 067393/0631 →
Continuity (1)
Related Publication 20250084214A1 · Mar 13, 2025
References Cited (35)
US 7074880B2 · Rhine et al. · 2006 [cited by applicant]
US 10800883B1 · Vivod et al. · 2020 [cited by applicant]
US 10907025B1 · Williams et al. · 2021 [cited by applicant]
US 11658398B1 · Downey · 2023 [cited by examiner]
US 20140350134A1 · Rodman · 2014 [cited by examiner]
US 20170355829A1 · Irvin · 2017 [cited by examiner]
US 20220363829A1 · Steiner, III et al. · 2022 [cited by applicant]
CN 111253614 · 2018 [cited by examiner]
M. A. B. Meador et al., “Polyimide aerogels with amide cross-links: a low cost alternative for mechanically strong polymer aerogels,” ACS Appl. Mater. Interfaces, vol. 7, No. 2, pp. 1240-1249, 2015. [cited by applicant]
H. Guo et al., “Polyimide aerogels cross-linked through amine functionalized polyoligomeric silsesquioxane,” ACS Appl. Mater. Interfaces, vol. 3, No. 2, pp. 546-552, 2011. [cited by applicant]
M. A. B. Meador et al., “Mechanically strong, flexible polyimide aerogels cross-linked with aromatic triamine,” ACS Appl. Mater. Interfaces, vol. 4, No. 2, pp. 536-544, 2012. [cited by applicant]
H. Guo et al., “Tailoring properties of cross-linked polyimide aerogels for better moisture resistance, flexibility, and strength,” ACS Appl. Mater. Interfaces, vol. 4, No. 10, pp. 5422-5429, 2012. [cited by applicant]
S. Ghaffari Mosanenzadeh, M. Alshrah, Z. Saadatnia, C. B. Park, and H. E. Naguib, “Double Dianhydride Backbone Polyimide Aerogels with Enhanced Thermal Insulation for High-Temperature Applications,” Macromol. Mater. Eng… [cited by applicant]
S. G. Mosanenzadeh, Z. Saadatnia, S. Karamikamkar, C. B. Park, and H. E. Naguib, “Polyimide aerogels with novel bimodal micro and nano porous structure assembly for airborne nano filtering applications,” RSC Adv., vol. … [cited by applicant]
M. A. B. Meador, M. Agnello, L. McCorkle, S. L. Vivod, and N. Wilmoth, “Moisture-resistant polyimide aerogels containing propylene oxide links in the backbone,” ACS Appl. Mater. Interfaces, vol. 8, No. 42, pp. 29073-290… [cited by applicant]
B. N. Nguyen, M. A. B. Meador, D. Scheiman, and L. McCorkle, “Polyimide aerogels using triisocyanate as cross-linker,” ACS Appl. Mater. Interfaces, vol. 9, No. 32, pp. 27313-27321, 2017. [cited by applicant]
W. Rhine, J. Wang, and R. Begag, “Polyimide aerogels, carbon aerogels, and metal carbide aerogels and methods of making same.” Google Patents, Jul. 11, 2006. [cited by applicant]
S. G. Mosanenzadeh, S. Karamikamkar, Z. Saadatnia, C. B. Park, and H. E. Naguib, “PPDA-PMDA polyimide aerogels with tailored nanostructure assembly for air filtering applications,” Sep. Purif. Technol., vol. 250, p. 117… [cited by applicant]
O. A. Tafreshi et al., “Novel, Flexible, and Transparent Thin Film Polyimide Aerogels with Enhanced Thermal Insulation and High Service Temperature,” J. Mater. Chem. C, 2022. [cited by applicant]
W. Chen, H. Yu, Q. Li, Y. Liu, and J. Li, “Ultralight and highly flexible aerogels with long cellulose I nanofibers,” Soft Matter, vol. 7, No. 21, pp. 10360-10368, 2011. [cited by applicant]
H. Guo, M. A. B. Meador, L. S. McCorkle, D. A. Scheiman, J. D. McCrone, and B. Wilkewitz, “Poly(maleic anhydride) cross-linked polyimide aerogels: synthesis and properties,” RSC Adv., vol. 6, No. 31, pp. 26055-26065, 20… [cited by applicant]
S. Wu, A. Du, S. Huang, W. Sun, Y. Xiang, and B. Zhou, “Solution-processable polyimide aerogels with high hydrophobicity,” Mater. Lett., vol. 176, pp. 118-121, 2016. [cited by applicant]
S. Qiao, S. Kang, Z. Hu, J. Yu, Y. Wang, and J. Zhu, “Moisture-resistance, mechanical and thermal properties of polyimide aerogels,” J. Porous Mater., vol. 27, No. 1, pp. 237-247, 2020. [cited by applicant]
H. Guo et al., “Flexible Polyimide Aerogels with Dodecane Links in the Backbone Structure,” ACS Appl. Mater. Interfaces, vol. 12, No. 29, pp. 33288-33296, 2020. [cited by applicant]
J. P. de Oliveira, G. P. Bruni, S. L. M. El Halal, F. C. Bertoldi, A. R. G. Dias, and E. da Rosa Zavareze, “Cellulose nanocrystals from rice and oat husks and their application in aerogels for food packaging,” Int. J. B… [cited by applicant]
J.-H. Kim, H.-R. Kim, H.-H. Park, and S.-H. Hyun, “Aging effect of SiO2 xerogel film on its microstructure and dielectric properties, ” Appl. Surf. Sci., vol. 169, pp. 452-456, 2001. [cited by applicant]
J.-K. Hong, H.-S. Yang, M.-H. Jo, H.-H. Park, and S.-Y. Choi, “Preparation and characterization of porous silica xerogel film for low dielectric application,” Thin Solid Films, vol. 308, pp. 495-500, 1997. [cited by applicant]
C. Wang, W. Chen, C. Xu, X. Zhao, and J. Li, “Fluorinated polyimide/POSS hybrid polymers with high solubility and low dielectric constant,” Chinese J. Polym. Sci., vol. 34, No. 11, pp. 1363-1372, 2016. [cited by applicant]
S. G. Mosanenzadeh, Z. Saadatnia, F. Shi, C. B. Park, and H. E. Naguib, “Structure to properties relations of BPDA and PMDA backbone hybrid diamine polyimide aerogels,” Polymer (Guildf)., vol. 176, No. February, pp. 213… [cited by applicant]
P. Gupta, B. Singh, A. K. Agrawal, and P. K. Maji, “Low density and high strength nanofibrillated cellulose aerogel for thermal insulation application,” Mater. Des., vol. 158, pp. 224-236, 2018. [cited by applicant]
C. Gong, J. Ni, C. Tian, and Z. Su, “Research in porous structure of cellulose aerogel made from cellulose nanofibrils,” Int. J. Biol. Macromol., vol. 172, pp. 573-579, 2021. [cited by applicant]
H. Liu et al., “Enhanced thermal shrinkage behavior of phenolic-derived carbon aerogel-reinforced by HNTs with superior compressive strength performance,” Ceram. Int., vol. 47, No. 5, pp. 6487-6495, 2021. [cited by applicant]
Z. Yang, H. Yu, X. Li, H. Ding, and H. Ji, “Hyperelastic and hydrophobic silica aerogels with enhanced compressive strength by using VTES/MTMS as precursors,” J. Non. Cryst. Solids, vol. 525, p. 119677, 2019. [cited by applicant]
H. Yang, X. Kong, Y. Zhang, C. Wu, and E. Cao, “Mechanical properties of polymer-modified silica aerogels dried under ambient pressure,” J. Non. Cryst. Solids, vol. 357, No. 19-20, pp. 3447-3453, 2011. [cited by applicant]
L. Zhao et al., “Theoretical and experimental investigation of haze in transparent aerogels,” Opt. Express, vol. 27, No. 4, pp. A39-A50, 2019. [cited by applicant]