Polyimide/Carboxylated Multi-walled Carbon Nanotube Hybrid Aerogel Fibers for Fabric Sensors: Implications for Information Acquisition and Joule Heating in Harsh Environments

Abstract

Polymeric hybrid sensors have garnered great interest in health monitoring, human−computer interaction, and soft robotics for their lightweight, flexibility, and feasible fabrication process. However, polymeric hybrid sensors suitable for harsh environments remain a considerable challenge, limiting further application. Herein, polyimide (PI)/carboxylated multi-walled carbon nanotube (c-MWCNT) hybrid aerogel fibers with a micro-porous structure were fabricated via wet-spinning and chemical thermal imidization. The fabricated PI/c-MWCNT hybrid aerogel fibers' conductivity and the change of current in response to the bending degree were tested, in which the relative current change achieved 4.78% with a bending degree of 150°. The fibers possessed a density of 0.41 ± 0.06 g/cm 3 , a conductivity of 17.8 ± 2.9 μS/m, and a tensile strength of 13.0 ± 1.1 MPa. In addition, they exhibited excellent heat/cold durability, whose decomposition temperature, cold resistance, and service life were 367 °C, −196 °C, and 300 cycles, respectively. Furthermore, the fabric sensor woven with PI/c-MWCNT hybrid aerogel fibers demonstrated two sensitivity stages of stage 1 (S 1 ) = 6.04 and stage 2 (S 2 ) = 0.55 under various pressures. Besides, it could be heated to 62 °C at a voltage of 30 V in 90 s with a changing resistance. The above properties demonstrate that the as-prepared fabric sensor exhibited great application potential for information acquisition and joule heating in harsh environments.

Innovations in spider silk‐inspired artificial gel fibers: Methods, properties, strengthening, functionality, and challenges

“…Ultrahigh-porous polymer aerogel fibers with thermal stability and exceptional mechanical strength, are highly sought after for applications in monitoring devices and thermal insulation, particularly in harsh environments 204,278,[293][294][295][296][297] However, the existing polymer aerogel fibers experience limitations regarding their thermal stability and mechanical properties, which restrict their potential applications. 298 To address this, Li et al 299 utilized a wet-spinning approach followed by a freeze-drying method to develop aerogel fibers based on aramid nanofibers.…”

Topological Polymer Networks-Enabled Mechanically Strong Polyamide-Imide Aerogel Fibers for Thermal Insulation in Harsh Environments

“…These mechanically strong PAI/ PU@340 aerogel fibers were remarkably superior to the already-reported aerogel fibers, such as aramid (8.1 MPa, 19.2%), 27 cellulose acetate/poly(acrylic acid)@cellulose nanofiber (CA/PAA@CNF: 5.83 MPa, 8.9%), 35 PI (11 MPa, 29.5%), and PI/carboxylated multiwalled carbon nanotube (PI/c-MWCNT: 13 MPa, 22.1%). 26,36 The intuitive comparison to illustrate the superior mechanical property of PAI/ PU@340 aerogel fibers is given by Figure 3e, and the detailed information about their mechanical performances could be found in Table S2. 27,36−40 These results declared the successful improvement of functional topoarchitected polymer networks.…”

“…24,25 Liu et al's work demonstrated that polyamide acid fibers were fabricated via wet spinning first; then, heating-induced imidization was conducted to obtain PI aerogel fibers. 26 This imidization procedure makes the whole process more tedious and hard to control on the one hand; even worse, it would cause the shrinkage of fibers and destroy the designed pore structure, which plays a key role in regulating the thermal insulation performance. Another drawback for fabricating PI aerogel fibers lies in the environmental hazards of coagulation bath, such as triethylamine.…”

“…As an acknowledged thermally stable and flame-retardant polymer, polyimide (PI) shows advantages as the raw material of thermal insulating aerogel fibers, especially when it is used under extreme environments. − However, the mechanical properties of already-reported PI aerogel fibers (less than 30 MPa) are far away from being used for practical occasions. Also, because of their intrinsically unsolvable property, PI aerogel fibers could not be directly spun. , Liu et al’s work demonstrated that polyamide acid fibers were fabricated via wet spinning first; then, heating-induced imidization was conducted to obtain PI aerogel fibers . This imidization procedure makes the whole process more tedious and hard to control on the one hand; even worse, it would cause the shrinkage of fibers and destroy the designed pore structure, which plays a key role in regulating the thermal insulation performance.…”