Ultralight, highly flexible in situ thermally crosslinked polyimide aerogels with superior mechanical and thermal protection properties via nanofiber reinforcement

Pan, Yu; Zheng, Jing; Xu, Yangyang; Chen, Xiaogang; Yan, Mengmeng; Zhao, Xiaojian; Feng, Yanlai; Ma, Yuhan; Ding, Mengyuan; Wang, Rongwu; He, Jie

doi:10.1016/j.jcis.2022.07.144

Cited by 25 publications

(14 citation statements)

References 46 publications

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“…The term aerogel is used to describe a family of open porous solids that can be fabricated from a wide variety of base materials, polymer aerogels were designed with the primary aim of developing superinsulators with good mechanical properties in a wide temperature range. [9][10][11][12] Among these materials, polyimide and polyamide aerogels have the most promising properties enabling aerospace and electronic applications. [13][14][15][16] In general, the cost of polyimide aerogels are high due to the need of expensive chemicals for synthesizing the polymer backbone.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Hydration Induced Stiffening and Subsequent Plasticization of Polyamide Aerogel

Moldován

Forgács

Paul

et al. 2023

Adv Materials Inter

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The mesoporous polyamide (PA) aerogel similar in chemical structure to DuPont's Kevlar is an advanced thermal insulation material tested in airspace applications. Unfortunately, the monolithic aerogel readily absorbs humidity (from moist air), which dramatically alters its mechanical properties. The compressive strength of the PA aerogel first increases when its water content increases, but subsequently decreases following additional hydration. To provide a coherent explanation for this non-monotonic change, the aerogel is hydrated stepwise and its hydration mechanism is elucidated by multiscale experimental characterization. The molecular structure is investigated by solid-state and liquid-state nuclear magnetic resonance (NMR) spectroscopy, and the morphology by small angle neutron scattering (SANS) at each equilibrium hydration state. The physico-chemical changes in the molecular level and in the nanoscale architecture are reconstructed. The first water molecules bind into the vacancies of the intermolecular H-bonding network of the PA macromolecules, which strengthens this network and causes concerted morphological changes, leading to the macroscopic stiffening of the monolith. Additional water disrupts the original H-bonding network of the macromolecules, which causes their increased segmental motion, marking the start of the partial dissolution of the nanosized fibers of the aerogel backbone. This eventually plasticizes the monolith.

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Section: Introductionmentioning

confidence: 99%

Mechanism of Hydration Induced Stiffening and Subsequent Plasticization of Polyamide Aerogel

Moldován

Forgács

Paul

et al. 2023

Adv Materials Inter

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“…Thermal conductivity of PIFs in the (a) vertical direction and (b) horizontal direction; (c) comparison of thermal conductivity between this work and literature values, including ANF/PI aerogel (), MXene/PI aerogel (), silica aerogel (), PI/aramid sponge (), PI/ANF aerogel (), PI foam plastic (), PI/red phosphorus/graphene foam (), MXene/ANF/PI aerogel (), PI foam (), CNTs@CoFe2O4/PI aerogel (), IBNR-PI aerogel (); (d) thermal insulation mechanism of PIFs in different directions; (e) changes of top surface temperature of PIFs in both vertical and horizontal directions; (f) infrared thermal images of PIFs [f 1 : side view (i.e., horizontal direction), f 2 : top view (vertical direction), f 3 : 3D infrared thermal images].…”

Section: Resultsmentioning

confidence: 97%

“…Globally, more than 30% energy consumption is used for daily heating and cooling, and improving energy efficiency is essential for the sustainability of society. − The use of thermal insulation materials is becoming critical for protecting human bodies and maintaining proper functions of devices, especially in the fields of space, marine, and nuclear reactors, among others. Nowadays, rubber foams, polyurethane (PU) foams, and polystyrene (PS) foams are employed as thermal insulation materials; however, these materials cannot maintain their original properties when they are subjected to extreme cold/heat conditions, let alone the poor thermal stability and flammability of the above-mentioned products. − Thus, it becomes imperative and challenging to develop lightweight, highly elastic thermal insulation materials, which can be targeted for ultralow/high temperature applications. , …”

Section: Introductionmentioning

confidence: 99%

Microwave-Assisted Foaming of Mechanically Robust Lightweight Polyimide Foams with Anisotropic Pore Structures for Thermal Insulation Applications

Luo

Wang

et al. 2023

Ind. Eng. Chem. Res.

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Mechanically robust lightweight polyimide foams (PIFs) with anisotropic pore structures were successfully prepared using microwave-assisted foaming and thermal imidization. The foaming behavior of polyester ammonium salt powders was assessed by rheological and TG-FTIR analyses. The release of volatile gases (e.g., H 2 O, tetrahydrofuran, and methanol) between 85 and 150 °C led to the directional growth of foam pores during microwave treatment, which was critical for endowing PIFs with excellent thermal insulation and mechanical properties. The use of 4,4′-diaminobenzanilide (DABA) as the copolymerization reagent enhanced the compressive strength@50% strain (92.25 kPa) in the vertical direction (i.e., pore growth direction) and high elasticity in the horizontal direction (compression response rate reached up to 98.95%). The PIFs demonstrated exceptional thermal stability under both inert and air atmospheres. Meanwhile, PIFs exhibited anisotropic thermal insulation behavior, exhibiting a thermal conductivity as low as 0.0264 W/(m•K) in the horizontal direction (i.e., perpendicular to the pore growth direction), which was ideal for thermal insulation purpose under high temperatures. Therefore, PIFs with excellent mechanical performance and exceptional heat resistance and thermal insulation properties were facilely prepared, which show promising applications in high-end engineering sectors.

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“…However, this material has high density, leading to an increase in thermal conductivity. Polyimide (PI) nanofiber aerogels that combine high thermal stability and glass transition temperature with lightweight, flexible, and thermal insulation for aerospace and other applications have a great amount of interesting work which has been reported by several research groups. − In previous studies, PI aerogels manufactured from different chemistries and starting monomers via an imidization process possessed large shrinkage (30–50%) during PI aerogel formation. − Greiner et al manufactured PI nanofiber aerogel from poly(amic acid) PAA and pyromellitic dianhydride via electrospinning and an imidization reaction based on the concept of “self-gluing” the fibrous network skeleton of PI during sponge formation . Thermal imidization using the protocol with the annealing specimen at high temperature caused shrinkage and setback the mechanical stability during PI aerogel formation.…”

Section: Introductionmentioning

confidence: 99%

Cross-linked Polyimide Nanofibrous Aerogels with Hierarchical Cellular Structure for Thermal Insulation

Thi Khuat,

Doan,

Phong Vo

et al. 2023

ACS Appl. Polym. Mater.

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Due to their low bulk density, high porosity, and functional performance, aerogels are ideal candidates for a variety of applications. However, their potential application in a variety of fields is limited by their time-consuming and costly complex fabrication process. In this study, electrospun 3-aminopropyltriethoxysilane-grafted polyimide (PI@APTES) nanofibers were used to construct nanofibrous aerogels (NFAs) via freeze-drying a dispersion of cross-linked-PI short fibers and a binder (PI@APTES), resulting in improved properties and functionalities. A highly siloxane cross-linked network structure was formed by hydrolysis and condensation reactions to generate stable nanofibrous aerogels. The obtained polyimide nanofibrous aerogels (PiNFAs) had a hierarchically three-dimensional (3D) microporous structure, high porosity (over 98%), tunable densities (10.6 ± 0.7–13.6 ± 0.2 mg cm–3), solvent resistance, superhydrophobicity (water contact angle over 163°), low thermal conductivity (as low as 33.2 mW m–1 K–1), and mechanical stability. These PiNFAs are promising candidates for potential applications in thermal insulation, lightweight construction, filtration, and sensors.

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Ultralight, highly flexible in situ thermally crosslinked polyimide aerogels with superior mechanical and thermal protection properties via nanofiber reinforcement

Cited by 25 publications

References 46 publications

Mechanism of Hydration Induced Stiffening and Subsequent Plasticization of Polyamide Aerogel

Mechanism of Hydration Induced Stiffening and Subsequent Plasticization of Polyamide Aerogel

Microwave-Assisted Foaming of Mechanically Robust Lightweight Polyimide Foams with Anisotropic Pore Structures for Thermal Insulation Applications

Cross-linked Polyimide Nanofibrous Aerogels with Hierarchical Cellular Structure for Thermal Insulation

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