Enhancing Bioinspired Aramid Nanofiber Networks by Interfacial Hydrogen Bonds for Multiprotection under an Extreme Environment

Abstract

In nature, many insects have evolved sclerotic cuticles to shelter their soft bodies, which are considered as "body armor". For beetles, the epidermis is composed of crosslinked intertwined fiber structures; such a fiber network structure could provide an anti-impact function for composites. Aramid nanofibers (ANFs) are of great interest in various applications due to their 1D nanoscale, high aspect ratio, excellent strength and modulus, and impressive chemical and thermal stability. In this paper, a kind of ANF network is prepared by a layer-by-layer assembly method. The enhancing ANF networks are developed by introducing carboxylated chitosan acting as a hydrogen-bondin donors as well as a soft interlocking agent (C-ANFs). As a result of the formation of a nanostructure and the hydrogen-bond interactions, the assembled C-ANF networks presented a high tensile strength (551.4 MPa) and toughness (4.0 MJ/m 2 ), which is 2.41 times and 32.69 times those of neat ANF networks, respectively. The excellent mechanical properties endow C-ANF networks with distinguished anti-impact performance. The specific dissipated energy after mass normalization reaches 7.34 MJ/kg, which is significantly superior to traditional protective materials such as steel and Kevlar composites. A nonlinear spring model is also used to explain the mechanical behavior of C-ANF networks. In addition to anti-impact protection, C-ANF networks can realize more than 99% of UV irradiation absorption and have excellent thermal stability. The chemical stability of C-ANF networks make them survive in acid and alkali environments. The above characteristics show that C-ANF networks have great application value in multiscale protection scenarios under an extreme environment.

Self-Assembly of Ultrathin, Ultrastrong Layered Membranes by Protic Solvent Penetration

“…ANFs were first prepared by the Kotov group through the deprotonation of PPTA fibers . Due to its excellent processability and strength, ANFs are considered as a highly promising nanosized building blocks for advanced materials with various macroscopic morphologies, such as film − and aerogel. , The super intrinsic strength and high processability make ANFs a good choice for preparing ultrathin and ultrastrong membranes in our study.…”

“…In the measurement, the velocity of a projectile was gradually increased until a perforation was generated in the films. The ballistic energy absorption can be calculated according to eq , Q = m p v 1 2 − m p v 2 2 2 m f where m p is the mass of the projectile, m f is the mass of the nanofiber in the projectile strike area, and v 1 and v 2 are the velocities of the projectile before and after impacting the films, respectively. The ballistic energy absorption capacity of ANF_AA was calculated to be 4.2 MJ kg –1 , which is higher than that of ANF_FA (3.5 MJ kg –1 ).…”

Programmable, Changeable, Origami Cellulose Films for Magnetically Controllable Soft Robots

“…With cellulose as a binder, the cross-linked network formed by the cellulose nanofibers can be used to cross-link the magnetic BaFe 12 O 19 particles. Due to the formation of nanostructures and hydrogen bonding interactions between the cellulose nanofiber networks, the film-forming ability and mechanical properties of the magnetic particles are effectively improved. , Compared with the fragile magnetic particles, the mechanical strength of the assembled magnetic cellulose film is 5 MPa (Figure S6). Benefiting from the appropriate mechanical properties, the magnetic cellulose films with stable interfaces can be easily stretched, bent, and twisted, demonstrating good flexibility.…”

Epitaxial heterointerfacial electron bridge synchronizes oxygen evolution activity and stability on a layered double hydroxide surface

“…The degree of lattice matching between the catalyst and the support is an important factor that governs both the activity and stability of the catalyst. 41,43 Thus, to demonstrate the favorable regulation of the electron bridge Ni(OH) 2 on the heterojunction structure and the electron structure, density functional theory (DFT) calculations were conducted. The formation energy of FeCo-LDH on NFO and NF substrates was analyzed using the optimal configuration of LDH*/NFO and LDH/NF, respectively (Fig.…”