Tunable network architecture in a hydrogel with extreme vibration damping properties.

Damping technologies aim to control the loads and deformations generated by ambient or forced vibrations in structures and machineries used in transport applications and construction. Traditionally, the materials used in damping devices are of fossil origin, but viscoelastic biobased resources are an alternative source of damping materials. Here, we develop an alginate-based hydrogel system with diverse porosity topologies by including poloxamer 407 as a sacrificial porogen at varying concentrations.

Fully bio-based composite and modular metastructures.

The reliance on fossil-derived components in the design of metamaterials and metastructures presents sustainability and environmental challenges, prompting the development of alternative solutions. In response, this study proposes a fully bio-based and modular metastructure composed of rods extracted from the giant bamboo () and plant-based polymeric joints derived from soybean () and castor oil (), aiming to offer a sustainable alternative for load-bearing structural components. The research investigates the design, fabrication, and mechanical performance of a unit trussed cell (50 × 50 × 50 mm) engineered to exhibit auxetic-like chiral rotation and enhanced energy absorption under compressive loading.

Sustainable 4D Printed Meta Biocomposite Materials for Programmable Structural Shape Changing.

Biological structures provide inspiration for developing advanced materials from sustainable resources, enabling passive structural morphing. Despite an increasing interest for parsimony-oriented innovation, sustainable shape-changing materials based on renewable resources remain underexplored. In this work, the architecture of a single plant fiber cell wall (S, for instance) is simplified to design novel concepts of 4D printed tubular moisture-driven structural actuators, using the hygromorphic properties of continuous flax fiber (cFF) reinforced materials.

Generalisation of the yield stress measurement in three point bending collapse tests: application to 3D printed flax fibre reinforced hydrogels.

This paper describes the extrusion pressure's effect on composite hydrogel inks' filaments subjected to three point bending collapse tests. The composite considered in this work consists of an alginate-poloxamer hydrogel reinforced with flax fibres. Increased extrusion pressure resulted in more asymmetrical filaments between the support pillars.

Giant Cushioning Effect in Facile Polymer/Nanoclay-Coated Flexible Polyurethane Foams.

In this work, a flexible polyurethane (PU) foam/polymer/clay (PUF/PAASep) composite is prepared via a simple dip-coating method. The composite exhibits excellent damping properties under quasi-static compression, vibration transmissibility, and impact resistance. For the composite preparation, sepiolite (Sep) dispersion in a polyacrylic acid (PAA) solution is first homogenized and evaluated using microscopy, and the obtained PAASep suspension is used to coat the PU foam uniformly for optimization of the quasi-static mechanical performance of the foam composites.

Hydrogel-Based Artificial Synapses for Sustainable Neuromorphic Electronics.

Hydrogels find widespread applications in biomedicine because of their outstanding biocompatibility, biodegradability, and tunable material properties. Hydrogels can be chemically functionalized or reinforced to respond to physical or chemical stimulation, which opens up new possibilities in the emerging field of intelligent bioelectronics. Here, the state-of-the-art in functional hydrogel-based transistors and memristors is reviewed as potential artificial synapses.

Correction: Flax fibre reinforced alginate poloxamer hydrogel: assessment of mechanical and 4D printing potential.

Correction for 'Flax fibre reinforced alginate poloxamer hydrogel: assessment of mechanical and 4D printing potential' by Charles de Kergariou , , 2024, , 4021-4034, https://doi.org/10.1039/D4SM00135D.

Flax fibre reinforced alginate poloxamer hydrogel: assessment of mechanical and 4D printing potential.

The mechanical and printing performance of a new biomaterial, flax fibre-reinforced alginate-poloxamer based hydrogel, for load-bearing and 4D printing biomedical applications is described in this study. The-self suspendable ability of the material was evaluated by optimising the printing parameters and conducting a collapse test. 1% of the flax fibre weight fraction was sufficient to obtain an optimum hydrogel composite from a mechanical perspective.

Castor-oil biobased foam: the effect of the composition on the physical and mechanical properties a statistical mixture design.

PU foams are versatile materials that find applications in a wide range of products, from upholstery to packaging and construction. These foams consist primarily of two components, polyol and prepolymer, and their concentrations play a crucial role in determining their physical and mechanical properties. A second-order mixture design approach is used in this work to identify the significant components and their contributions on the physical-mechanical properties of biodegradable castor oil-based foams.

Experimental Study of Drilling Damage Outcomes in Hybrid Composites with Waste Micro-Inclusions.

Composite materials are used in a substantial number of products. Environmental concerns highlight the need for the inclusion of recovered waste in their formulation, thus reducing their carbon footprint. These solutions raise the need to confirm the mechanical characteristics of these materials, avoiding unwanted failures.

Exploiting nonlinearities through geometric engineering to enhance the auxetic behaviour in re-entrant honeycomb metamaterials.

Classical approaches to enhance auxeticity quite often involve exploring or designing newer architectures. In this work, simple geometrical features at the member level are engineered to exploit non-classical nonlinearities and improve the auxetic behaviour. The structural elements of the auxetic unit cell are here represented by thin strip-like beams, or thin-walled tubular beams.

Acoustic transmission loss in Hilbert fractal metamaterials.

Acoustic metamaterials are increasingly being considered as a viable technology for sound insulation. Fractal patterns constitute a potentially groundbreaking architecture for acoustic metamaterials. We describe in this work the behaviour of the transmission loss of Hilbert fractal metamaterials used for sound control purposes.

From trash to treasure: Sourcing high-value, sustainable cellulosic materials from living bioreactor waste streams.

The appreciation of how conventional and fossil-based materials could be harmful to our planet is growing, especially when considering single-use and non-biodegradable plastics manufactured from fossil fuels. Accordingly, tackling climate change and plastic waste pollution entails a more responsible approach to sourcing raw materials and the adoption of less destructive end-of-life pathways. Livestock animals, in particular ruminants, process plant matter using a suite of mechanical, chemical and biological mechanisms through the act of digestion.

Biobased and Programmable Electroadhesive Metasurfaces.

Electroadhesion has shown the potential to deliver versatile handling devices because of its simplicity of actuation and rapid response. Current electroadhesion systems have, however, significant difficulties in adapting to external objects with complex shapes. Here, a novel concept of metasurface is proposed by combining the use of natural fibers (flax) and shape memory epoxy polymers in a hygromorphic and thermally actuated composite (HyTemC).

Ionic Liquid-Based Polymer Nanocomposites for Sensors, Energy, Biomedicine, and Environmental Applications: Roadmap to the Future.

Current interest toward ionic liquids (ILs) stems from some of their novel characteristics, like low vapor pressure, thermal stability, and nonflammability, integrated through high ionic conductivity and broad range of electrochemical strength. Nowadays, ionic liquids represent a new category of chemical-based compounds for developing superior and multifunctional substances with potential in several fields. ILs can be used in solvents such as salt electrolyte and additional materials.

Large datasets of water vapor sorption, mass diffusion immersed in water, hygroscopic expansion and mechanical properties of flax fibre/shape memory epoxy hygromorph composites.

This data article presents four experimental sets of results related to flax fibre composites with epoxy shape memory polymer matrix: water vapor absorption, mass diffusion immersed in water, hygroscopic expansion, mechanical properties. The water vapor absorption tests are described in raw data related to four types of laminates with weights measured at different relative humidity (0%, 9%, 33%, 44%,75%, 85% and 100%). The mass diffusion experiments are related to weights of immersed samples over time.

Bentonite-based sodium alginate/ dextrin cross-linked poly (acrylic acid) hydrogel nanohybrids for facile removal of paraquat herbicide from aqueous solutions.

Removal of hazardous herbicides from the aqueous solution is critical for overcoming health-related issues across the wider population. In the current work, we have prepared sodium alginate (SAlg), dextrin, and acrylic acid (AA) based cross-linked hydrogels, composed of bentonite incorporated in the biocompatible hydrogel matrix. This hydrogel composite can remove highly toxic herbicide paraquat (PQ).

Effects of hydrogenation on the tensile and shear mechanical properties of defective penta-graphene.

Penta-graphene (PG) is a new theoretical two-dimensional metastable carbon allotrope composed entirely of carbon pentagons. In this paper, molecular dynamics simulations are performed to investigate the effects of the hydrogenation on the tensile and shear mechanical properties, together with the failure mechanism of PG with vacancy defects. The results show that hydrogenation can effectively tune the mechanical properties and failure mechanism of PG with vacancy defects.

Mechanics of penta-graphene with vacancy defects under large amplitude tensile and shear loading.

Penta-graphene is a new two-dimensional metastable carbon allotrope composed entirely of carbon pentagons with unique electronic and mechanical properties. In this work we evaluate the mechanical properties of new classes of defective penta-graphene (DPG) subjected to tensile and shear loading by using molecular dynamics simulations. The types of defects considered here are monovacancy at either 4-coordinated C1 site or 3-coordinated C2 site, and double vacancy (DV).

Biopolymeric Coacervate Microvectors for the Delivery of Functional Proteins to Cells.

The extent to which biologic payloads can be effectively delivered to cells is a limiting factor in the development of new therapies. Limitations arise from the lack of pharmacokinetic stability of biologics in vivo. Encapsulating biologics in a protective delivery vector has the potential to improve delivery profile and enhance performance.

Abnormal stiffness behaviour in artificial cactus-inspired reinforcement materials.

Cactus fibres have previously shown unusual mechanical properties in terms of bending and axial stiffness due to their hierarchical structural morphology. Bioinspiration from those cactus fibres could potentially generate architected materials with exciting properties. To that end we have built bioinspired artificial analogues of cactus fibres to evaluate their mechanical properties.

Chondroinduction of Mesenchymal Stem Cells on Cellulose-Silk Composite Nanofibrous Substrates: The Role of Substrate Elasticity.

Smart biomaterials with an inherent capacity to elicit specific behaviors of biological prompts would be advantageous for regenerative medicine applications. In this work, we employ an electrospinning technique to model the nanofibrous extracellular matrix (ECM) of cartilage using a chondroinductive cellulose and silk polymer blend (75:25 ratio). This natural polymer composite is directly electrospun for the first time, into nanofibers without post-spun treatment, using a trifluoroacetic acid and acetic acid cosolvent system.

Development of Cycloaliphatic Epoxy-POSS Nanocomposite Matrices with Lambas Enhanced Resistance to Atomic Oxygen.

The preparation of ultra-thin CFRP laminates, which incorporate a cycloaliphatic epoxy resin reinforced with polyhedral oligomeric silsesquioxane (POSS) reagent nanofiller, using out-of-autoclave procedure is reported. The influence of the amount of POSS within the laminate on the mechanical properties and surface roughness of the laminates is analysed before and after exposure to atomic oxygen (AO) to simulate the effects of low Earth orbit (LEO). The addition of 5 wt% POSS to the base epoxy leads to an increase in both flexural strength and modulus, but these values begin to fall as the POSS content rises, possibly due to issues with agglomeration.

Microwave Properties of Metacomposites Containing Carbon Fibres and Ferromagnetic Microwires.

The microwave properties of composites containing Fe-based ferromagnetic microwires and carbon fibres have been investigated as part of a campaign to bring added functionalities into structural composites. A transmission window observed in 1-6 GHz demonstrates double-negative (DNG), , metamaterial characteristics in the composites containing short-cut carbon fibres and a parallel array of microwires; the metamaterial characteristic is due to the ferromagnetic resonance and a plasmonic behaviour, as short carbon fibres are proved to ameliorate DNG properties through enhancing the impedance of the composites. In parallel, magnetically tunable metamaterial features are realised in composites containing continuous carbon fibres and microwires, which can be switched on/off via rotating the electrical excitation direction.

Strain Reversal in Actuated Origami Structures.

Origami in engineering is gaining interest for its potential as deployable or shape-adaptive structures. Practical systems could employ a network of actuators distributed across the structure to induce these deformations. Selecting the actuator locations requires an understanding of how the effect of a single actuator propagates spatially in an origami structure.