Synergistic enhancement of photothermal conversion and mechanical properties in PVA hydrogels via co-doping of polydopamine and gold nanoparticles

Synergistic enhancement of photothermal and mechanical properties in PVA hydrogels through polydopamine and silver nanoparticle integration

Zirconium carbide (ZrC) films are deposited onto polyester fabric through magnetron sputtering. The deposited films are then examined by using field scanning electron microscopy and energy dispersive X-ray spectroscopy. The photothermal conversion property, film thickness, infrared reflectance and transmittance, and thermal conductivity are also evaluated. The results show that the highest far-infrared emissivity of polyester fabric deposited with ZrC is 0.9379. The ZrC deposited samples showed a small increase in thermal conductivity with a difference of 0.0611W/m·K, and a higher photothermal conversion efficiency with a temperature increase of 27.5 °C in 100 s, when the thickness of the ZrC film is 1920 nm. These therefore indicate that coating fabrics with ZrC through magnetron sputtering is an environmentally friendly means to produce textiles with photo-thermal conversion and heat insulation properties.

At present, using biomass materials to modify graphene oxide (GO) to enhance the anticorrosion performance of coatings meets the requirements of future sustainable development. In order to endow lignin/GO coatings with self-healing function to reduce maintenance costs and avoid accidents caused by material corrosion failure, this work utilized electrostatic interactions to load zinc ions onto lignin/GO (Zn@LGO). Experimental results indicated that the cured coating exhibited both self-healing anticorrosion and photothermal conversion properties. When the content of Zn@LGO was 0.4 wt%, the surface temperature of the cured coating rose to 139.2 °C after 180 s of near-infrared radiation. The cured coating was left for 100 days in salt water, the Z0.01Hz value of coating VER-3 was up to 1.3 × 109 Ω cm2, which was two orders of magnitude higher than that of pure resin coating, and fewer corrosion products were observed on the metal surface. The scratch test showed that the damaged coating was soaked in 3.5 wt% sodium chloride for 72 h; the charge transfer impedance of coating VER-3 was 2.61 × 104 Ω cm2, which was one order of magnitude higher than that of pure resin coating. This was mainly because during metal corrosion, the hydroxide generated by the combination of hydroxide ions at the cathode and zinc ions covered the damaged area of cured coating, hindering the penetration of the corrosive medium. All in all, this research promoted the application of lignin, and also provided a reference for the design of composite coatings with both photothermal conversion and self-healing anticorrosion properties.

In this study, graphene oxide (GO) and polyacrylamide/polyacrylic acid (PAM/PAA) are used to prepare hydrogels with photothermal conversion properties for highly efficient uranium extraction from seawater. Zwitterionic 2‐methacryloyloxy ethyl phosphorylcholine (MPC) is introduced in the PAM/PAA/GO hydrogel to obtain PAM/PAA/GO/MPC (PAGM), exhibiting good antibacterial properties. PAGM demonstrates efficient and specific adsorption of uranium (VI) (U(VI)). Under light conditions, the adsorption capacity of PAGM reaches 196.12 mg g−1 (pH = 8, t = 600 min, C0 = 99.8 mg L−1, m/v = 0.5 g L−1). The adsorption capacity is only 160.29 mg g−1 under dark conditions (pH = 8, t = 600 min, C0 = 99.8 mg L−1, m/v = 0.5 g L−1). The adsorption capacity of light is 22.5% higher than that of dark. The adsorption process is fitted using the Langmuir and pseudo‐second‐order models. Furthermore, PAGM exhibits good repeatability and stability after five adsorption–desorption cycles. PAGM exhibits a U(VI) adsorption capacity of 6.1 mg g−1 after storage for one month in natural seawater. The X‐ray photoelectron spectroscopy (XPS) results demonstrate that the coordination of the amino, carboxyl, and hydroxyl groups with U(VI) is the primary mechanism of U(VI) adsorption. The mechanism is confirmed through detailed density functional theory calculations. PAGM demonstrates durability, high efficiency, photothermal conversion properties, and antibacterial properties. Thus, it is a promising candidate for uranium extraction from seawater.

Lignin reinforced hydrogels with multi-functional sensing and moist-electric generating applications

The controlled synthesis of branched Ag particles with modulated branch length and core size is crucial for optimizing their localized surface plasmon resonance (LSPR) and photothermal properties. Here, we reported a pH-mediated synthesis strategy to achieve systematic control over these structural parameters. By adjusting the pH of AgNO3 solutions, we prepared silver precursor solutions containing varying amounts of Ag2O particles and free silver ions. Upon introducing hydroxylamine as a reducing agent, the Ag2O intermediates underwent pseudomorphic transformation to form cores of branched Ag particles, while the remaining free silver ions were reduced to form branches through preferential growth of Ag (200) planes. These branches fused through oriented attachment and randomly attached to the cores, enabling the formation of branched particles. Adjusting the pH from 11.9 to 10.2 allowed controllable morphological evolution from cubic to branched structures, with the ratio of branch length to core size modulated from 0:1 to 1.6:1. This morphological control enabled a large red-shift of LSPR peaks from the visible range to the near-infrared II (NIR-II) window. Specifically, branched Ag particles prepared at pH 10.5, with an LSPR peak at 1025 nm, exhibited a photothermal conversion efficiency of up to 43.1% under 1064 nm irradiation. This work provides a robust platform for designing branched Ag particles with systematically controlled optical and photothermal conversion properties, paving the way for their advanced optical and biomedical applications.

Insights into the biomechanical properties of plasma treated 3D printed PCL scaffolds decorated with gold nanoparticles

Hydrogels are cross-linked networks containing water and are widely used in multiple fields due to their intrinsic softness and diffusive properties. One field of particular interest is in medical devices and tissue and organ engineering. Poly(vinyl alcohol) (PVA) is one common hydrogel where its mechanical properties can be changed by using different salt solutions, making it more appropriate for certain applications, such as artificial neuron tissue. In this study, we used the ReaxFF reactive forcefield to investigate PVA in lithium and potassium chloride. It was hypothesized that lithium might promote a proton transfer from the PVA hydroxyl groups, therefore inhibiting the PVA from forming hydrogen bonds with itself, yielding a weaker PVA hydrogel. Conversely, potassium would not promote a proton transfer, instead getting inside the PVA structure, allowing a higher density of hydrogen bonds to form, creating a stronger PVA hydrogel. We were able to show a proton transfer was favorable in the lithium case and unfavorable in the potassium case. This explains the differences in mechanical properties shown in experimental results and provides atomistic detail to motivate tunable mechanical properties in PVA hydrogels in various salt solutions.

New geopolymer-based materials offer excellent perspectives for the future; they should not be regarded as competitive materials for Portland cement, which has been the reference construction material for so long, but as alternative materials with a series of important advantages to be considered. Metakaolin (MK) produced from firing kaolin material up to 750 oC for 2 h with a heating rate of 5oC/min; leads to an enhancement in mechanical and microstructural properties of alkali activated geopolymer of water cooled slag material using (6:6, wt%) of sodium hydroxide and sodium silicate. In the present work the ratios of MK which will be added are less than 20% of the total mass, because of the used MK was very fine with average pore structure less than 30 mµ, which hinders the geopolymerization reaction if used as high ratio. Curing was performed under 100% relative humidity at a temperature of 38oC and ages of 7, 14, 28 & 90 days. The properties of geopolymer specimens have been studied through measurement of XRD, SEM imaging, FTIR, compressive strength and water absorption. Results showed that the mixes of metakaolin up to 15% results in an enhancement in the mechanical properties as compared with slag control mix up to 90 days.

Cryogenic treatment is the process of cooling a material to extremely low temperatures to generate enhanced mechanical and physical properties. The present investigation examines the effect of deep cryogenic treatment on the enhancement of mechanical properties, such as wear resistance, corrosion resistance, tensile strength and impact strength of the plunger material 100Cr6 bearing steel. The improvement in the wear resistance, corrosion resistance, tensile strength and impact strength of the deep cryogenically treated samples over the conventionally heat-treated ones, is 50%, 26%, 13% and 27% respectively. This study suggests that the formation of very small carbides dispersed in the tempered martensite structure, can be the main reason for the enhancement of certain mechanical properties, along with the retained austenite transformations.

Cryogenic treatment is the process of cooling a material to extremely low temperatures to generate enhanced mechanical and physical properties. The present investigation examines the effect of deep cryogenic treatment on the enhancement of mechanical properties, such as wear resistance, corrosion resistance, tensile strength and impact strength of the plunger material 100Cr6 bearing steel. The improvement in the wear resistance, corrosion resistance, tensile strength and impact strength of the deep cryogenically treated samples over the conventionally heat treated ones,is 50%, 26%, 13% and 27% respectively. This study suggests that the formation of very small carbides dispersed in the tempered martensite structure, can be the main reason for the enhancement of certain mechanical properties, along with the retained austenite transformations.

New geopolymer-based materials offer excellent perspectives for the future; they should not be regarded as competitive materials for Portland cement, which has been the reference construction material for so long, but as alternative materials with a series of important advantages to be considered. Metakaolin (MK) produced from firing kaolin material up to 750 ºC for 2 h with a heating rate of 5ºC/min; leads to an enhancement in mechanical and microstructural properties of alkali activated geopolymer of water cooled slag material using (6:6, wt%) of sodium hydroxide and sodium silicate. In the present work the ratios of MK which will be added are less than 20% of the total mass, because of the used MK was very fine with average pore structure less than 30 mµ, which hinders the geopolymerization reaction if used as high ratio. Curing was performed under 100% relative humidity at a temperature of 38ºC and ages of 7, 14, 28 & 90 days. The properties of geopolymer specimens have been studied through measurement of XRD, SEM imaging, FTIR, compressive strength and water absorption. Results showed that the mixes of metakaolin up to 15% results in an enhancement in the mechanical properties as compared with slag control mix up to 90 days.

Enhanced photothermal conversion properties of graphene aerogel surface and its application in oil spill treatment

Enhancement of mechanical properties and shape memory effect of Ti–Cr–based alloys via Au and Cu modifications

Cartilage cannot undergo spontaneous repair because of a lack of access to the blood supply, so cartilage defects progressively deteriorate into osteoarthritis. The typical approach for tissue engineering is the cultivation of cells on degradable scaffolds such as poly(glycolic acid) (PGA). The cartilage tissue that results from this method integrates well with surrounding tissue when implanted into cartilage defects. However, the mechanical and biochemical properties are inferior to healthy cartilage, and the tissue eventually degrades. Poly(vinyl alcohol) (PVA) hydrogels, on the other hand, have long been studied for cartilage replacement because of their similar mechanical and material properties, but their complete lack of integration with surrounding cartilage as implants has impeded their utility. The combination of the integrative properties of PGA scaffolds with the mechanical properties of PVA hydrogels may allow their use as implants. PVA hydrogels were made porous through a novel technique of microparticle incorporation. Average pore sizes ranged from 60 to 300[mu]m. Cartilage cells could be seeded throughout the porous network and induced to develop healthy cartilage tissue. Since PVA hydrogels are nondegradable, the result was a hybrid hydrogel-cartilage construct that may integrate well with surrounding tissue. Moreover, the nondegradable nature of the PVA hydrogel would prevent the mechanical properties from diminishing over time, as is the case with degradable scaffolds. These superporous, semi-degradable hydrogels were evaluated as cartilage replacement materials in terms of their dynamic structure, mechanical properties, and swelling properties, over the course of swelling in model osmotically conditioned systems. The hydrogels were then characterized for their ability to support cartilage formation by encapsulated cells and the effects of controlled release of growth factors to enhance cartilage formation and integration between the hydrogels and the surrounding tissue. The results demonstrate that these PVA-based hydrogels have the potential to effectively replace damaged cartilage, because they have similar mechanical and swelling properties that are stable over the long-term, and support cartilage formation and integration with surrounding tissue. A novel technique is also described for evaluating the swelling properties of biomaterials in a model system that can be applied to many other types of biomaterials and tissues.