The bottom‐up synthesis for aramid nanofibers: The influence of copolymerization

Shi, Yifei; Qiu, Teng; Tuo, Xinlin

doi:10.1002/app.49589

Cited by 20 publications

(14 citation statements)

References 41 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The PANF dispersion is prepared through the “bottom-up” polymerization method proposed by our group, ,− in which the formation of PANF could be controlled by the hydrophilic auxiliaries, shearing effect, coagulating bath composition, and polymerization parameters (the monomer concentration, CaCl 2 concentration, and comonomer). The as-prepared PANF in dispersion is displayed in Figure a.…”

Section: Results and Discussionmentioning

confidence: 99%

Macroscopic-Scale Preparation of Aramid Nanofiber Aerogel by Modified Freezing–Drying Method

et al. 2021

Self Cite

View full text Add to dashboard Cite

Aerogel has been widely known as a low-density and highly porous material and is closely connected with the complex processing methods, such as freeze−drying or supercritical drying. In this work, using the polymerization-induced aramid nanofiber (PANF) as a building block, we put forward a modified freezing−drying method for the high-efficiency preparation of all-para-aromatic-amide aerogels. In the preparation process, PANF hydrogel is first frozen at −18 °C and then dried at 20−150 °C for the formation of PANF aerogel. The PANF framework formed during the freezing process is crucial for the formation of the PANF aerogel. Moreover, the space-occupying effect of ice crystals is also helpful for the formation of the macroscopic pore structure in the aerogel. Aerogels with large size or well-controlled shape could be successfully obtained by this method. Through the variation of PANF concentration in the hydrogel and drying temperature, aerogels with different densities (20−185 mg/cm 3 ) could be achieved, and the lowest density is reached at 150 °C, with the PANF concentration of 0.7%. The low-density PANF aerogels show high specific compressive strengths and low thermal conductivities, which are comparable to those resulting from the freeze−drying or supercritical drying method. Furthermore, the shrinkage phenomenon in the drying process could be skillfully utilized for the preparation of PANF aerogel-coated objects. The PANF aerogels could be applied as a thermal insulating material or shock absorption material in practical applications.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Macroscopic-Scale Preparation of Aramid Nanofiber Aerogel by Modified Freezing–Drying Method

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Calcium chloride powder (CaCl 2 , purity 98.5%, Sinopharm Chemical Reagent Co., Ltd., China) was heated at 450 °C for 4 h to remove the trace water before using. The PANF dispersion was prepared by polymerization-induced self-assembly method according to our previous work. , PANF aerogel films with a bulk density of 62 mg/cm 3 and a thickness of about 0.8 mm were obtained from the PANF dispersion via the combination of the vacuum-assisted filtration and freeze-drying procedure. The inherent viscosity (η inh ) of PPTA used for PANF fabrication was 3.0 dL/g measured by an Ubbelohde viscometer at 30 °C under the concentration of 0.5 g/dL in the solution of 98% sulfuric acid.…”

Section: Methodsmentioning

confidence: 99%

The Aramid-Coating-on-Aramid Strategy toward Strong, Tough, and Foldable Polymer Aerogel Films

et al. 2022

Self Cite

View full text Add to dashboard Cite

Aerogel has been much highlighted as an emerging lightweight thermal insulation material, but problems such as fragility, low strength, liquid permeability, and lack of flexibility greatly limit further applications. In this work, a facile aramid-coating-on-aramid (ACoA) method is demonstrated to fabricate all-aramid aerogel composite films for thermal insulation. The method started from the bottom-up synthesis of polymerization-induced para-aramid nanofibers (PANF), which were easily transformed into aerogel films through the vacuum-assisted filtration followed by the freeze-drying techniques. Then, the heterocyclic aramid (HA) solution prepared through the low-temperature-solution polycondensation was used as the coating to be applied onto the PANF aerogel films, and composite films of HA/PANF aerogel were simply achieved with HA contributed to the dense and continuous surface layer. The bulk HA film is of superior mechanical and thermal properties to those of the PANF film. Moreover, reliable interfacial interlocking structures were developed beneath the outermost surface via the interpenetration of the infiltrated HA with PANF network. The comprehensive result was the 15 times enhanced tensile strength, 33 times enhanced fracture toughness, the high thermal decomposition temperature, and the additional flexibility for the foldable films of HA/PANF aerogel. The sealing of the surface macropores greatly suppressed the surface chalking and high water absorption. However, the survival of the tiny pores inside the composite maintained the low enough level of the thermal conductivity to provide effective protections against high temperature not only in air but also under wet or even liquid conditions, suggesting the broader applications for thermal insulation.

show abstract

“…In addition to the di-component copolymerization system of PPD and TPC, the polymerization-induced assembly strategy is also suitable for the fabrication of aramid nanofibers with the copolymerization of third co-monomers. In order to illustrate this, Shi et al [ 44 ] separately introduced three kinds of third monomer, m -phenylenediamine, 4,4-diaminodiphenyl ether and 2,5-dichloro-1,4-phenylenediamine, into the polymerization-induced self-assembly process of PPTA, and nanofiber aqueous dispersions were all obtained with subtle differences in micromorphology ( Figure 7 A). The side groups of copolymerized aramids were of benefit for the decreasing of ANF diameter.…”

Section: Self-assembly Of Pptamentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

“…In China, Shandong Jufan Ltd. has built up a production line of PANF with an output of 300 ton In addition to the di-component copolymerization system of polymerization-induced assembly strategy is also suitable for the fa nanofibers with the copolymerization of third co-monomers. In order et al [44] separately introduced three kinds of third monomer, m-phe diaminodiphenyl ether and 2,5-dichloro-1,4-phenylenediamine, into induced self-assembly process of PPTA, and nanofiber aqueous disp tained with subtle differences in micromorphology (Figure 7A). The s ymerized aramids were of benefit for the decreasing of ANF diameter monomer, 2-(4-aminophenyl)-5-aminobenzimidazole, was also intro in the polymerization-induced self-assembly of PPTA, and the ribbon work formed in the process of aggregation (Figure 7B).…”

Section: Polymerization-induced Self-assembly Of Pptamentioning

confidence: 99%

See 1 more Smart Citation

Recent Advances in Self-Assembly and Application of Para-Aramids

Xie

Yang

et al. 2022

Molecules

Self Cite

View full text Add to dashboard Cite

Poly(p-phenylene terephthalamide) (PPTA) is one kind of lyotropic liquid crystal polymer. Kevlar fibers performed from PPTA are widely used in many fields due to their superior mechanical properties resulting from their highly oriented macromolecular structure. However, the “infusible and insoluble” characteristic of PPTA gives rise to its poor processability, which limits its scope of application. The strong interactions and orientation characteristic of aromatic amide segments make PPTA attractive in the field of self-assembly. Chemical derivation has proved an effective way to modify the molecular structure of PPTA to improve its solubility and amphiphilicity, which resulted in different liquid crystal behaviors or supramolecular aggregates, but the modification of PPTA is usually complex and difficult. Alternatively, higher-order all-PPTA structures have also been realized through the controllable hierarchical self-assembly of PPTA from the polymerization process to the formation of macroscopic products. This review briefly summarizes the self-assembly methods of PPTA-based materials in recent years, and focuses on the polymerization-induced PPTA nanofibers which can be further fabricated into different macroscopic architectures when other self-assembly methods are combined. This monomer-started hierarchical self-assembly strategy evokes the feasible processing of PPTA, and enriches the diversity of product, which is expected to be expanded to other liquid crystal polymers.

show abstract

The bottom‐up synthesis for aramid nanofibers: The influence of copolymerization

Cited by 20 publications

References 41 publications

Macroscopic-Scale Preparation of Aramid Nanofiber Aerogel by Modified Freezing–Drying Method

Macroscopic-Scale Preparation of Aramid Nanofiber Aerogel by Modified Freezing–Drying Method

The Aramid-Coating-on-Aramid Strategy toward Strong, Tough, and Foldable Polymer Aerogel Films

Recent Advances in Self-Assembly and Application of Para-Aramids

Contact Info

Product

Resources

About