Publications

Di/polysulfide linkages in vulcanizates can be thermally cleaved to initiate the addition of functional vinyl monomers into rubber skeletons, leading to the formation of functionalized diene-elastomers via dynamic covalent polymerization.

Vitrimers are a class of covalently cross-linked polymers that have drawn great attention due to their fascinating properties such as malleability and reprocessability. The state of art approach to improve their mechanical properties is the addition of fillers, which, however, greatly restricts the chain mobility and impedes network topology rearrangement, thereby deteriorating the dynamic properties of vitrimer composites. Here, we demonstrate that the integration of sacrificial bonds into a vitrimeric network can remarkably enhance the overall mechanical properties while facilitating network rearrangement. Specifically, commercially available epoxidized natural rubber is covalently cross-linked with sebacic acid and simultaneously grafted with N-acetylglycine (NAg) through the chemical reaction between epoxy and carboxyl groups, generating exchangeable β-hydroxyl esters and introducing amide functionalities into the networks. The hydrogen bonds arising from amide functionalities act in a sacrificial and reversible manner, that is, preferentially break prior to the covalent framework and undergo reversible breaking and reforming to dissipate mechanical energy under external load, which leads to a rarely achieved combination of high strength, modulus, and toughness. The topology rearrangement of the cross-linked networks can be accomplished through transesterification reactions at high temperatures, which is accelerated with the increase of grafting NAg amount due to the dissociation of transient hydrogen bonds and increase of the ester concentration in the system.

An advanced elastomer was developed by incorporating a dual-dynamic network into <italic>cis</italic>-polyisoprene, which combines excellent mechanical properties with high self-healing capability.

Sodium deoxycholate (SDC), a kind of bile derivative, is used to noncovalently functionalize graphene. Stable and high concentration (up to 20 mg ml −1 ) of graphene colloid is obtained. The stabilization mechanism is revealed to be hydrophobic interaction, electrostatic repulsion and hydrogen bonding. Single-layer and few-layer graphene are obtained in the colloid. Subsequently, the obtained graphene sheets are incorporated into a polyvinyl alcohol (PVA) matrix by solution casting to fabricate PVA/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the PVA matrix and strong interfacial adhesion between them. Significant improvements in tensile strength and modulus of the composite films are observed.

Rubbers are strategically important due to their indispensable applications in the daily life and high-tech fields. For their real-world applications, the covalent cross-linking, reinforcement, and malleability of rubbers are three important issues because they are closely related to the elasticity, mechanical properties, and recycling of the rubber materials. Herein, we demonstrate a simple way to prepare covalently cross-linked yet recyclable and robust elastomeric vitrimer composites by incorporating exchangeable β-hydroxyl ester bonds into the elastomer-nanoparticle interface using epoxy group-functionalized silica (Esilica) as both cross-linker and reinforcement in carboxyl group-grafted styrene-butadiene rubber (CSBR). The Esilica-cross-linked CSBR composites exhibit promising mechanical properties due to the covalent linkages in the interface and fine silica dispersion in the matrix. In addition, the interface can undergo dynamic reshuffling via transesterification reactions to alter network topology at high temperatures, conferring the resulting composites the ability to be reshaped and recycled.

Graphene oxide was directly reduced into graphene in N-methyl-pyrrolidone with the assisted-dispersion of vapor grown carbon nanofibers (VGCF), resulting in a homogeneous dispersion of VGCF–graphene hybrid filler (VGCF–G). In the hybrid filler, VGCF served as effective stabilizers for graphene by adsorbing VGCF onto graphene through π–π interaction. Subsequently, the as-prepared VGCF–G was incorporated into a bio-based polyester (BE) to prepare BE/VGCF–G composites by solution blending. In the composites, graphene was complete exfoliated with the assisted-dispersion of VGCF. Simultaneously, graphene acted as “compatibilizer” to improve the dispersion of VGCF and enhance the interfacial adhesions. As a consequence, the binary combination of VGCF and graphene showed remarkable synergistic effects in improving the electrical conductivity and mechanical properties of the BE/VGCF–G composites. For example, at the filler content of 4.8vol%, the electrical conductivity of BE/VGCF–G composite is about 4 orders of magnitude higher than BE/VGCF composite containing VGCF alone, and the ultimate stress and modulus of BE/VGCF–G composite is 58% and 45% higher than those for BE/VGCF composite. Furthermore, multi-stimuli responsive shape memory performances (electro-activated and infrared-triggered) of the composites were investigated. BE/VGCF–G composites showed a combination of higher shape memory recovery, stronger recovery stress and faster response, compared with BE/VGCF composites.

ABSTRACT To address the increasingly diverse demands in modern society, it is essential to develop multifunctional textiles that possess both thermoregulation and UV‐resistant properties. This study integrates coaxial and uniaxial electrospinning techniques to create multifunctional phase change nanofibers (PCNF) that exhibit high levels of hydrophobicity, ultraviolet (UV) resistance, and thermoregulation. During the coaxial electrospinning process, the thermal regulation of the nanofiber membrane is enhanced by incorporating octadecane into the core layer, resulting in a latent heat value of 82.47 J/g. Adding TiO 2 to the sheath layer significantly enhances the nanofibers' UV resistance, achieving a UV protection factor of 200.5. Furthermore, the inclusion of pearl‐like microspheres through uniaxial electrospinning significantly boosts the hydrophobicity of the PCNF, resulting in a water contact angle (WCA) of 148° and excellent stain‐resistant characteristics. This multifunctional composite membrane thus offers a highly promising solution for both outdoor protective applications and flexible wearable devices.

Nanostructured LiBH4 with greatly improved de-/hydrogenation thermodynamics and kinetics has been attracting the ever-growing interest for on-board hydrogen storage applications. However, it is challenging to controllably fabricate various nanostructures of LiBH4 due to its strong reducibility, high chemical activity and sensitivity to water and oxygen. Here, we demonstrate the very first success in tailoring the nanoscaled LiBH4 morphology from nanorods to nanoparticles by using few-layer graphenes (FL-Grs) as supporters. The presence of 30 wt% FL-Grs is optimal because it contributes not only substantial nucleation sites for LiBH4 nanoparticles but also sufficient catalytic activity for hydrogen storage in LiBH4. The resultant LiBH4-30 wt% FL-Grs displays 20–50 nm-sized particles in morphology, which enables the complete reversible storage of 7.2 wt% H2 starting from 230 ºC for desorption and 190 ºC for absorption along with a stable cyclability, greatly superior to pristine sample and even the nano-LiBH4/FL-Grs mixture. The somewhat particle growth as well as the segregation and isolation of B and LiH with cycling is reasonably responsible for the gradually slowed desorption/absorption kinetics. This important insight guides the design and development of nanostructured LiBH4-based composites featured high capacity and long life by combining nanometer size effect and catalytic effect.

The SiO2 insulating layer was prepared on the FeSiCr powders successfully by one-step dumping sol-gel method and ammonia was used as the catalyst. It is found that the growth of SiO2 layer can be tuned by the ammonia concentration. Within the reaction time of 0.5 h, SiO2 grows with heterogeneous nucleation when the ammonia concentration is 0.08–0.16 ml/g, and SiO2 coating layer was relatively uniform. With a high ammonia concentration of 0.20–0.24 ml/g, SiO2 grows with both heterogeneous and homogeneous nucleation, and SiO2 particles gathered and grew. The saturation magnetization and effective permeability of FeSiCr@SiO2 SMCs gradually decrease with the increase of ammonia concentration, while the specific resistance, quality factor and DC-bias property increase. With the ammonia concentration of 0.12 ml/g, the thickness of SiO2 insulating layer was about 30–60 nm. The annealed FeSiCr@SiO2 soft magnetic composite shows good soft magnetic performance with effective permeability and core loss of 45.52 and 418.32 kW/m3 at 0.05 T and 100 kHz, respectively, and the quality factor of 76.5 at 1 MHz.