Calcium alginate (CA) beads as a green sorbent were easily fabricated in this study using sodium alginate crosslinking with CaCl₂, and the crosslinking pathway was the exchange between the sodium ion of α-L-guluronic acid and Ca(II). The experimental study was conducted on Cu(II), Cd(II), Ni(II) and Zn(II) as the model heavy metals and the concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The characterization and sorption behavior of the CA beads were analyzed in detail via using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption experiments demonstrated that the CA beads exhibited a high removal efficiency for the selective adsorption of Cu(II) from the tetra metallic mixture solution and an excellent adsorption capacity of the heavy metals separately. According to the isotherm studies, the maximum uptake of Cu(II) could reach 107.53 mg/g, which was significantly higher than the other three heavy metal ions in the tetra metallic mixture solution. Additionally, after five cycles of adsorption and desorption, the uptake rate of Cu(II) on CA beads was maintained at 92%. According to the properties mentioned above, this material was assumed to be applied to reduce heavy metal pollution or recover valuable metals from waste water.

In this work, cellulose nanocrystal (CNC) was modified by an ureido-pyrimidinone (UPy) system based on quadruple hydrogen bondings, and CNC-UPy was obtained. Then, this powder was added into polyvinyl alcohol (PVA), and PVA/CNC-UPy composite membranes and hydrogels were prepared. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarizing optical microscopy (POM) and particle size distribution (PSD) were used to characterize CNC-UPy. From the FTIR results, the characteristic peaks of NCO group sat 2270 cm⁻¹ disappeared, indicating the successful synthesis of CNC-UPy. XRD results showed that the modification by UPy may change the structure of CNC and its degree of crystallinity was increased. PSD analysis showed that the particle size of CNC was increased and its size distribution became narrower after modification by UPy groups. The structure and properties of the composite membranes and hydrogels were studied by differential scanning calorimeter (DSC), thermogravimetric analysis (TGA) together with investigation of swelling, sustained release and self-healing performances. DSC curves depicted that the glass transition temperature, T_g, of different PVA membranes was increased with addition of different proportions of CNC-UPy. TGA data showed that the temperature of maximum weight loss rate was increased, which illustrated the enhanced thermal stability of PVA/CNC-UPy composites. Meanwhile, it was also revealed that the PVA/CNC-UPy composite hydrogels possess good self-healing and better sustained release behavior for the soil conditioner, fulvic acid (FA).

A new nanoencapsulation was established in which small nanocapsules with a natural polymeric wall could be fabricated, capsulizing the capsaicin having pungent odor. The new nanoencapsulation is based on a simple coacervation process. In this technique, gelatin was used as the wall material of the nanocapsules, and an insoluble polymer film was formed after cross‐linking reaction. The shell formation mechanism and the effects of the process conditions such as shearing force, the gelatin viscosity, cross‐linking time, and so on, on the particle size of the nanocapsulated capsaicin (NC) agents were discussed. Meanwhile, the morphology and size distribution of the nanocapsules prepared by the most suitable conditions, were analyzed by Fourier transform infrared (FTIR) spectroscopy, laser particle size analyzer, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The NC agents had a mean particle size of about 100 nm. Moreover, the thermal properties of the NC agents were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was demonstrated that the melting point and thermal pyrolysis temperature of the NC agents were improved from 75 to 100°C, 230 to 240°C, 310 to 320°C, and from 450 to 540°C compared with that of the uncovered capsaicin, which were caused by the encapsulation of the cross‐linked gelatin over the surface of the capsaicin.

Thermally conductive polymer composites show attractive prospects as thermal management materials in many applications such as microelectronic devices. However, traditional approaches in the preparation of thermally conductive polymer composites usually have the disadvantages of complex processes. In this study, a facile method for highly thermally conductive silicone rubber composites is reported, based on 3D interconnected graphene sponges by using an inorganic salt as a sacrificial template. The composites exhibit a high thermal conductivity of 1.50 W m⁻¹ k⁻¹ and a thermal conductivity enhancement of 752% at a very low graphene loading of 1.46 wt%. More significantly, highly thermally conductive epoxy and styrene–butadiene rubber composites are also fabricated by the same method. The composites also show excellent electrical insulating properties (>10¹³ Ω cm). Thus, this effective method is proved to be widely used for the facile fabrication of polymer composites of both plastic and rubber matrices which are thermally conductive and have excellent electrical insulating properties.

Traditional flexible electronic sensing materials have fallen short in meeting the diverse application needs and environments of modern times. Hence, we require a multi-functional elastomer material to improve the overall performance and expand the functionality of flexible electronic sensors. In this study, we fabricated a multi-block polyurethane (PU) elastomer based on semi-crystalline polycaprolactone (PCL) chain segments and highly flexible polydimethylsiloxane (PDMS) chain segments, which showcases outstanding mechanical properties, self-healing capabilities, and recyclability. By adjusting the ratio parameters of the chain segments, we were able to modulate the thermodynamic behavior, hydrophobicity, mechanical behavior, and self-healing properties of the designed PU elastomers. The optimized ratios exhibited good tensile strength (16.26 MPa), high elongation at break (3300.84%), good toughness (278.82 MJ m⁻³, fracture energy ≈ 234.96 KJ m⁻²), high self-repairing (≈100%, at room temperature for 12 h), efficient recyclability, and puncture resistance. Self-healing is accomplished through the interactions between dynamic disulfide bonds, dynamic boron–oxygen bonds, and hydrogen bonds. The conductive ink (PEDOT:PSS) was encapsulated within this elastomer to construct a flexible electronic sensor, attaining excellent sensing performance (stable output for 1000 cycles). This multi-functional polyurethane elastomer acts as an ideal matrix material for flexible electronic sensors, offering novel concepts and perspectives for the next generation of green electronic flexible materials, electronic flexible robots, and other stimulus-responsive materials.