Fabrication and applications of polyimide nano-aerogels

Shi, Baolu; Ma, Bin; Wang, Chenqi; He, Haibo; Qu, Lijie; Jin, Xiaochao; Chen, Yanfei

doi:10.1016/j.compositesa.2021.106283

Cited by 43 publications

(23 citation statements)

References 71 publications

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“…14 Despite all of the advantages, their inherent fragility also affects any application. 15,16 Therefore, polyimide aerogels (PIA) are of great interest due to their ability to withstand high temperatures, 17,18 their exceptional thermal stability, 19 and their favorable mechanical properties, making PIA the material of choice in the thermal insulation field in the aerospace industry. 20,21 At present, the matrix of PIA has the problems of large drying shrinkage and insufficient thermal insulation performance.…”

Section: Introductionmentioning

confidence: 99%

“…Silica aerogels are the most welcome and the darling among these aerogels which have excellent properties such as high specific area, high porosity, and extremely low thermal conductivity . Despite all of the advantages, their inherent fragility also affects any application. , Therefore, polyimide aerogels (PIA) are of great interest due to their ability to withstand high temperatures, , their exceptional thermal stability, and their favorable mechanical properties, making PIA the material of choice in the thermal insulation field in the aerospace industry. , …”

Section: Introductionmentioning

confidence: 99%

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Polyimide Aerogels with Excellent Thermal Insulation, Hydrophobicity, Machinability, and Strength Evolution at Extreme Conditions

Zhang

Wang

et al. 2022

ACS Appl. Polym. Mater.

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High performance polyimide aerogels (PIA) are highly desirable as a part of thermal protection systems for aircraft. However, the large drying shrinkage and insufficient thermal insulation of PIA limit their practical applications in the aerospace field. Herein, the strategy of two-step prepolymerization and polycondensation route was proposed to fabricate PIA with ultralow drying shrinkage, outstanding thermal insulation, hydrophobicity, machinability, compressive strength in cryogenic/high-temperature atmospheres, flame resistance, and fantastic dimensional stability. In more detail, the drying shrinkage rate of PIA series can be lowered to 1.84%, mainly owing to the strengthened skeletons by chemical bond formation and physical entanglement of molecular chains. Excellent thermal insulation is reflected upon keeping an ink drop state as long as 265 s despite placing it on a cold surface with a temperature of −196 °C. PIA-O2B2 are imparted with hydrophobic properties (with water contact angle of 135°) depending on the hydrogen-bonding interaction between polyimide networking chains and 1H,1H,2H,2H-perfluorodecyltriethoxysilane that was introduced. In addition, the exceptional flame retardant is endowed completely, which is attributed to the evidence of the presence of aromatic ring structures in constructing the aerogel. The high-temperature shrinkage rate of PIA series is as low as 4.81% due to the relative small free volume of the molecular chains. Our study would provide a method for designing ultralow drying shrinkage and superb thermal insulation in cryogenic conditions for PIA in aerospace uses.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polyimide Aerogels with Excellent Thermal Insulation, Hydrophobicity, Machinability, and Strength Evolution at Extreme Conditions

Zhang

Wang

et al. 2022

ACS Appl. Polym. Mater.

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“…Although PI is an insulating polymer and a poor electrical conductor compared to polymers like polyaniline, EMI shielding materials made with PI nano-carbon composites have performed reasonably well in electromagnetic wave absorption [14][15][16]. Latest advances also led to the fabrication of PI foam aerogels [17,18]. They were mainly developed for super-elasticity at deep cryogenic temperatures for aerospace applications.…”

Section: Introductionmentioning

confidence: 99%

Polyimide foam composites with nano-boron nitride (BN) and silicon carbide (SiC) for latent heat storage

Clausi

Zahid

Shayganpour

et al. 2022

Adv Compos Hybrid Mater

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Leaching and instability in wax-based phase change materials (PCMs) are serious application problems. Herein, we developed paper-like (~ 100 µm) flexible, composite PCMs by hydraulic compression of 1-cm-thick polyimide foams between an aluminum foil and a (nano) ceramic composite Parafilm®. An unfilled PCM film placed between the foam and the aluminum surface ensured strong adhesion between the collapsed foam and the metal. Different concentrations of nano-BN and micro-SiC particles were compounded into Parafilm® in order to optimize the thermal performance. Based on infrared imaging, the monoliths containing 30 wt% micro-SiC outperformed all other systems including BN/SiC hybrids. The next best thermal performance was observed with the 60 wt% nano-BN composite. Due to compression, the cellular structure of the polyimide foams collapsed irreversibly while being impregnated by the PCMs from both sides. High-k fillers improved impregnation into the collapsed foam and enabled excellent shape stability and leakage prevention. Graphical abstract

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“…Polyimide (PI) aerogels have received wide attention because of their low density, stable mechanical properties, and low thermal conductivity [1]. Aerogels are highly porous materials for various applications, but they are often limited by their poor mechanical strength and thermal stability [2].…”

Section: Introductionmentioning

confidence: 99%

3D Printing of Thermal Insulating Polyimide/Cellulose Nanocrystal Composite Aerogels with Low Dimensional Shrinkage

Feng

Yü

2021

Polymers

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Polyimide (PI)-based aerogels have been widely applied to aviation, automobiles, and thermal insulation because of their high porosity, low density, and excellent thermal insulating ability. However, the fabrication of PI aerogels is still restricted to the traditional molding process, and it is often challenging to prepare high-performance PI aerogels with complex 3D structures. Interestingly, renewable nanomaterials such as cellulose nanocrystals (CNCs) may provide a unique approach for 3D printing, mechanical reinforcement, and shape fidelity of the PI aerogels. Herein, we proposed a facile water-based 3D printable ink with sustainable nanofillers, cellulose nanocrystals (CNCs). Polyamic acid was first mixed with triethylamine to form an aqueous solution of polyamic acid ammonium salts (PAAS). CNCs were then dispersed in the aqueous PAAS solution to form a reversible physical network for direct ink writing (DIW). Further freeze-drying and thermal imidization produced porous PI/CNC composite aerogels with increased mechanical strength. The concentration of CNCs needed for DIW was reduced in the presence of PAAS, potentially because of the depletion effect of the polymer solution. Further analysis suggested that the physical network of CNCs lowered the shrinkage of aerogels during preparation and improved the shape-fidelity of the PI/CNC composite aerogels. In addition, the composite aerogels retained low thermal conductivity and may be used as heat management materials. Overall, our approach successfully utilized CNCs as rheological modifiers and reinforcement to 3D print strong PI/CNC composite aerogels for advanced thermal regulation.

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Fabrication and applications of polyimide nano-aerogels

Cited by 43 publications

References 71 publications

Polyimide Aerogels with Excellent Thermal Insulation, Hydrophobicity, Machinability, and Strength Evolution at Extreme Conditions

Polyimide Aerogels with Excellent Thermal Insulation, Hydrophobicity, Machinability, and Strength Evolution at Extreme Conditions

Polyimide foam composites with nano-boron nitride (BN) and silicon carbide (SiC) for latent heat storage

3D Printing of Thermal Insulating Polyimide/Cellulose Nanocrystal Composite Aerogels with Low Dimensional Shrinkage

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