GIANT最新文献

Traditional impact-resistance materials relying on the combination of supporting materials and energy-dissipation elastomers can effectively reduce shock load, yet the sharp interface between two types of materials causes discontinuous stress transfer and cracking. Here, inspired by the squid beak, we report a type of high impact-resistance gradient elastomers with large-scale modulus gradient with about three orders of magnitude (modulus range of 7 × 10³ ∼ 7 × 10⁶ Pa) and high energy dissipation (loss factor > 0.6) over a wide temperature range by diffusively introducing stiff polymers in a highly damping elastomer with controlled mechanical properties. Under the action of an external force, our gradient elastomers exhibit soft-while-stiff attributes, combining cushioning and support. In drop hammer impact tests, our gradient materials can reduce impact strength by 80 %, significantly better than commercial protective gear. It is worth mentioning that the modulus of the bottom layer matches that of the tissues for better protection.

Silicon (Si) is a promising substitute for graphite anode due to the high theoretical specific capacity (4200 mAh g⁻¹). However, too large volume change exists during the lithiation/delithiation process. Composite anode, prepared by mixing Si with graphite, can realize higher specific capacity than graphite and much better cycle performance than Si anode. However, the capacity decay caused by pulverization of Si particles is still a great challenge. Here, a cross-linkable binder rich in nitrile, carboxyl and hydroxyl groups is designed for composite silicon-graphite (Si-C) anode. The nitrile and hydroxyl groups can be in situ cross-linked in the batteries through Ritter reaction. The cross-linked binder has excellent resilience and good adhesion to the active materials and current collector. The cycle performance of the cell with cross-linked binder is much better than the counterpart. Scanning electron microscopy results of the cycled Si-C anode show that the cross-linked binder can suppress the volume expansion and pulverization. Moreover, the investigation with X-ray photoelectronic spectrum and density function theory calculation demonstrate that the decomposition of ester solvent and LiPF₆ on Si anode has been mitigated and more stable SEI film is formed on the Si-C anode. Our strategy of in situ cross-linking binder in the batteries has provided a feasible way for designing the next generation of silicon-based anodes with higher specific capacity and longer cycling life.

The recent discovery of liquid-matter ferroelectrics not only opens a door to explore novel polar matter states and properties in the term of condensed matter physics but also provides unprecedented opportunities for developing new liquid crystal materials and technologies. The progression from the ferroelectric nematic phase to many other liquid-matter ferroelectrics represents a remarkable journey in emerging polar soft matter. In this perspective, we briefly introduce the latest quick rise and advancements of liquid-matter ferroelectrics that display the nematic and smectic characteristics. We summarize the recently-discovered new polar phases, their new physics, and potential technological innovations, and then give some hints that we consider critical for further exploration. More importantly, we seek to delve into broader discussions on chemical structure design, the underlying physical interactions driving various polar states, and their connections to a range of intriguing phenomena.

Biomineralization plays an important role in various physiological activities in both nature and living organisms. Organisms regulate the crystal nucleation, crystal phase, and crystal growth kinetics of inorganic phases through organic regulation, forming minerals with multi-level order, thereby playing a role in biological support, protection, and metabolic regulation. Unlike general inorganic minerals, biominerals are subtly regulated by organic organisms (such as small organic molecules, peptides, proteins, nucleic acids) and complex environments, possessing biological characteristics and becoming a part of living organisms. It can be seen that the process of biomineralization is not only the process of manufacturing biomaterials, but also the process of using materials to regulate organisms themselves. The biomimetic strategy based on biomineralization can achieve a huge transformation from the biomimetic preparation of functional materials to the biomimetic composite of organisms and materials. In this review, we briefly introduce biomimetic structures inspired by nature itself, and emphasize the important role of the relationship between organisms and materials in the process of biomineralization. We also briefly explore biominerals and their mechanisms. At the same time, a series of functional materials (such as self-cleaning hydrophobic materials, artificial spider silk fibers, mother of pearl like composite materials, humidity responsive materials, and bioprinting materials) synthesized through biomimetic strategies inspired by biomanufacturing materials were systematically elucidated. And a brief discussion was given on the synthesis of new functional organisms using biomimetic strategies to regulate organisms, such as using functional materials to regulate biomimetic repair of hard tissues, using biomineralization strategies to coat vaccines to improve their thermal stability during transportation and drug delivery efficiency in vivo, and constructing functional biomimetic artificial organelles on demand. Finally, this article summarizes the current opportunities and challenges based on biomineralization, providing further feasible guidance for future material regulation of life.

Cholesteric liquid crystals, also known as chiral nematics, possess a right-angle helicoidal structure with pitch in the submicrometer and micrometer range. Although the possibility of getting optical reorientation in this kind of materials has been considered since the discovery of giant optical nonlinearity in nematic liquid crystals, a significant light-induced modulation of the helical structure has shown to be a challenging task. The recent experimental realization of a chiral phase with an oblique helicoidal structure, identified as the heliconical phase predicted by Meyer and DeGennes in 1968, offers the opportunity to observe such an optical reorientation of the optic axis. This paper is a brief review of the nonlinear optical properties of these unconventional chiral nematic liquid crystals and is aimed at showing that the world of liquid crystalline phases can still amaze with new material properties and new physics.

We present a liquid-crystal laser device based on the chiral ferroelectric nematic phase (N_F*). The laser medium is obtained by mixing a ferroelectric nematic material with a chiral agent and a small proportion of a fluorescent dye. Notably, in the N_F* phase very low electric fields perpendicular to the helical axis are able to reorient the molecules, giving rise to a periodic structure whose director profile is not single harmonic but contains the contribution of various Fourier components. This feature induces the appearance of several photonic bandgaps whose spectral ranges depend on the field, which can be exploited to build tunable laser devices. Here we report the characterization of home-made N_F* lasers that can be tunable under low electric fields and present laser action in two of the photonic bands of the material. The obtained results open a promising route for the design of new and more versatile liquid-crystal based lasers.

In this work, for the first time, films were obtained based on biodegradable polyhydroxyalkanoates (PHAs) - a copolymer of 3-hydroxybutyrate-co-3-hydroxyvalerate P(3HB-co-3HV) and a copolymer of 3-hydroxybutyrate-co-4-hydroxybutyrate P(3HB-co-4HB), containing drugs of different chemical structure and action - antibiotics (ceftazidime, doripenem), antiseptic (chlorhexidine) and tissue regeneration stimulator (Actovegin) for drug delivery and cell culture. Using SEM, AFM and measuring the contact angles of water wetting, it is shown how PHAs composition and loading of films of P(3HB-co-3HV) and P(3HB-co-4HB) with drugs affect the porosity, roughness indicators and adhesive properties of the surface. The constructed films are a depot form of drug, the release of which in vitro is realized for a long time, without burst releases, corresponds to Korsmeyer-Peppas and Higuchi models with diffusion character. Films loaded with antibiotics have pronounced antibacterial activity and suppress the development of pathogens S. aureus and E. coli, without a pronounced negative effect on the adhesion and proliferation of epidermal cells. In the cultures of human keratinocytes HaCaT it was shown that the presence of actovegin, as well as ceftazidime in the films, exhibits a stimulating effect, increasing their number. The results demonstrate the suitability of the depot-films for cellular technologies and are promising for the reconstruction of tissues complicated by infection.

Ferroelectric nematic liquid crystals exhibit unique non-linear optical properties, with the potential to become transformative materials for photonic applications. A promising direction relies on the fabrication of tailored polar orientational patterns via photoalignment, thus shaping the non-linear optical susceptibility through thin slabs of the ferroelectric fluid. Here, we explore the fabrication of 2D periodic SHG active arrays in ferroelectric nematic fluids, for different materials, cell thicknesses and motifs. Based on polarizing optical microscopy observations in combination with optical simulations, second harmonic generation microscopy and interferometry, the 3D structure of the motifs is revealed. Two different 2D periodic patterns are explored, showing that the balance between flexoelectric and electrostatic energy can lead to different domain structures, an effect which is rooted in the difference between the flexoelectric properties of the materials. It is shown that by combining the surface-inscribed alignment with different spontaneous degrees of twist, 2D SHG active arrays can be obtained in the micrometre scale, in which adjacent areas exhibit maximum SHG signals at opposite angles.

The aqueous solution of regenerated silk fibroin (RSF) is considered as the raw material to produce various silk protein-based materials, including hydrogel, film, rod and fiber, etc. with significant mechanical properties. However, the aqueous solution of RSF is usually unstable within a few days or even hours in terms of its essential properties, because the conformation of the RSF chain would spontaneously transfer from random coil to β-sheet in water. In this work, we developed a way to harvest the RSF powder through an optimized spray drying method via rapid drying at a relatively low temperature. It was demonstrated that no severe degradation and conformational transition of the RSF chain occurred during powder preparation, and the RSF powder exhibited remarkable solubility in water and long stability at room temperature. Importantly, there are no obvious differences in the mechanical properties of the silk protein-based materials made from the aqueous solution from the spray-dried RSF powder (Sp-RSF) and from fresh RSF solution. Indeed, such amorphous Sp-RSF powder, in which the protein chain was dominated by random coil conformation, not only promised as the raw material for large-scale silk protein-based products in various applications but also provided the basis for fabricating bulk silk protein materials via the untraditional processing of silk fibroin, such as molding with the help of heat and moisture.

A surface in contact with the isotropic phase of a passive liquid crystal can induce nematic order over distances that range from microscopic to macroscopic when the nematic-isotropic interface undergoes an orientational-wetting transition. If the nematic is active, what happens to the interface? Does it propagate and, if it does, is its structure different from the passive one? In this paper, we address these questions. We investigate how the active nematic-isotropic interface is affected by the anchoring strength of the surface, the bulk ordering field and the activity. We find that while passive interfaces are one-dimensional the active ones exhibit two dynamical regimes: a passive-like regime and a propagating regime where the interfaces propagate until the entire domain is active nematic. Active interfaces break the translational symmetry within the interfacial plane above a threshold activity, where the active nematic fluctuations, which are ultimately responsible for the emergence of an active turbulent nematic phase, drive non-steady dynamical interfacial regimes.