GIANT最新文献

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.

Dissipative solitons in liquid crystals (LCs) are represented by three-dimensional solitary waves of director deformation called directrons. The only one exception on the quasi-static counterparts of directrons has ever been observed in achiral nematics. In this work, quasi-static solitons and their fission are identified in chiral nematics. The structure, distribution and fission of quasi-static solitons are closely related to the pitch of samples. The critical pitch is about 7.0 µm for LC cells with thickness of ∼10.0 µm. Quasi-static solitons are transformed from directrons by stepping down voltage to facilitate locating solitons. Successive two-soliton fission with increasing fission time occurs for all quasi-static solitons in samples of relatively larger pitches. Multi-soliton fission is also found in some quasi-static solitons when the voltage is stepped up back to the directron domain, leaving behind a region that can modify the trajectories of surrounding directrons. The fission of quasi-static solitons in chiral nematics has predictable fission location, adjustable fission time, and controllable fission number, may acting as an excellent model system for studying general principles of soliton fission in nonlinear systems.

This paper describes the two-dimensional (2D) crystallization of side-chain giant molecules (SCGMs) having the fixed number ratio of two types of functionalized building blocks with 1:1. SCGMs are regarded to a certain degree as size-amplified versions of universal synthetic polymers that are prepared by precisely connecting molecular nanoparticles (MNPs) to polymer chains. Our previous experimental results have shown that individually changing the number ratio of one of the building blocks would significantly affect the structural parameters of molecular crystals, mainly the longitudinal thickness. Herein, we systematically discussed the 2D crystallization of two categories of POSS-based SCGMs with constant building blocks ratio. Solution self-assembly of such SCGMs resulted in well-defined 2D nanosheets with similar structural configurations, showing great tolerance in the number of building blocks. Subsequently, we proposed a “sandwiched-type” mode to illustrate the bilayer 2D supramolecular framework, in which crystalline blocks pack in head-to-head manner. In addition, sequence isomers provide an ideal platform to further verify that the thickness of 2D nanocrystal is linked with the tethering density determined by the number ratio of building blocks. We believe that this study could be a better complement to our previous work and then make us to be more in-depth understand the crystallization mechanism of SCGMs.

Solid polymer electrolytes (SPEs) with wide electrochemically stable window and high lithium-ion transference number (t_Li⁺) are a requirement for high energy density lithium batteries. Here, we construct a copolymer electrolyte (PDA) with ether-ester bifunctional groups that exhibits a low highest occupied molecular orbital (HOMO) energy level by in situ polymerization. Compared to the poly(1,3-dioxolane) (PDOL) pure polyether electrolyte, the weakening of the ion-dipole interaction between lithium salt and polymer in the PDA electrolyte promotes the formation of a “weak solvation” structure. Therefore, the electrolyte achieves high oxidative stability (4.6 V vs. Li⁺/ Li with a standard leakage current of 10 μA), high Li⁺ transference number (0.60), and importantly, derives a stable LiF-rich composition on high voltage cathode surface. Which ultimately enables stable cycling of Li||LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) batteries at a range of 3.0–4.3 V. This work provides a fundamental understanding of the design of antioxidant SPEs to achieve high energy density lithium batteries.

Polyolefins are the most produced and widely used polymeric materials. However, the chemically inert nature of polyolefins has led to severe environmental pollution, posing a threat to human sustenance and development. Managing and recycling polyolefin plastic waste is crucial for the transition from a linear to a sustainable circular economy. Catalytic chemical recycling includes traditional techniques like pyrolysis and photolysis, and innovative methods that introduce chemical cleavable bonds into the polyolefin chain for closed-loop recycling. Catalytic post-functionalization of post-consumer polyolefin materials is another strategy to tackle plastic waste, aiming to upgrade the materials’ utility and contribute to sustainability. Overall, developing catalytic methods for deconstructing and upcycling plastics is essential to encourage better reclamation practices and reduce the environmental impact of plastic waste.

Organic electrochemical transistors (OECT) have shown great potential in diverse applications; however, in many OECTs, their slow transient response has thus far limited their practical use. One reason for the slow response is the complex interplay between lateral and vertical ion transport that has so far been poorly understood. In this work, we study the impact of lateral ion transport on OECT transient response, introduce a robust pre-charging method to manipulate the slow lateral ion transport. This approach leads to quicker ion redistribution and improved switching speeds. We show the general utility of pre-charging method in enhancing the switching speeds across various material systems, characterized by both low and high ion mobilities, and across different device architectures, achieving nearly symmetric speeds for both on-switching and off-switching. Moreover, we showcase the efficacy of the pre-charging method in enabling slow OECTs to capture rapid signals in real-world applications. Our findings present a groundbreaking strategy for enhancing the response times of OECT devices and deepening our understanding of the transient mechanisms in OECT device.

Sugar-based block co-oligomer (BCO) consisting of saccharide block exhibits high segregation strength that overcomes the limitation of the traditional block copolymers for accessing the ordered nanostructures with ultrasmall feature size. This study explores the influence of molecular chirality on the self-assembly behavior of glucose-block-tocopherol (Glc-b-Toc) BCOs, wherein the Toc blocks were either pure in chirality or being a mixture of the stereoisomers. Both the chiral and racemic BCOs formed a hexagonal perforated layer (HPL) structure with an unusually small aspect ratio (c/a) of the unit cell, attributable to the propensity of the Glc block to enhance hydrogen bonding formation. As the temperature was increased, the dominance of hydrogen bonding interactions diminished, resulting in a gradual increase in the c/a ratio and eventually a transformation of the HPL structure to a double gyroid (DG) phase. The chirality of the Toc block enhanced the effective segregation strength of the BCO, leading to elevated order-order transition temperatures associated with the HPL-to-DG and DG-to-hexagonally packed cylinder (HEX) transitions. Within the HPL phase window, the chiral BCO exhibited significantly slower kinetics during thermally-induced structural reorganization in adjusting the c/a ratio, especially in the cooling process. Consequently, a pronounced hysteresis in the structural reorganization of the chiral BCO was observed. This phenomenon was ascribed to the chiral interaction between the Toc blocks, which limited the diffusion of the BCO molecules for the structural reorganization.