Search

The permanently chemically cross‐linking solid–solid phase change materials (SSPCMs) were designed to solve the problem of leakage and poor shape stability during the whole process of phase transformation. However, these materials lead to environment pollution and resources waste because of the non‐recyclability. Therefore, a SSPCMs was fabricated using dynamic thermal reversible Diels–Alder bonds. The prepared SSPCMs exhibited excellent shape, heat storage stability, and reliability and reprocessed ability, resulting from dynamic Diels–Alder bonds. Moreover, the Halloysite nanotubes decorated with Fe3O4 nanoparticles (HNTs@Fe3O4) were used to enhance the thermal conductivity of SSPCMs. When the filler content was 0.5 wt%, the best integrated properties (phase change properties and thermal conductivity) of the SSPCMs were obtained, it had the highest melting and freezing phase change enthalpies about 116.8 and 127.2 J/g, and thermal conductivity value, 0.223 W/m K, which was 101% higher than pure SSPCMs. Hence, the prepared SSPCMs can be considered as promising save‐energy, friendly‐environment thermal management materials. [ABSTRACT FROM AUTHOR]

In this work, a crosslinker terminal maleimide groups (EDM) has been synthesized and was used in reactions with the pendant furan groups of polyurethane (PUE) to prepare the self-healing electrically conductive composites based on Diels-Alder reaction, and Ag nanowires (AgNWs) as the conductive network inlaid in the surface layer of the polymer matrix layer. Inspired by the graphene-based materials for its versatility in both material and chemical properties, and we present a new synthetic strategy for the preparation of functional graphene nanosheets with DA group that can be employed in the self-healing polyurethane system. To our best knowledge, it hasn't been reported yet the structure graphene oxide materials (rmGO) in any systems. The rmGO served as fillers to reinforce the composites and would participated in the DA reactions. The excellent NIR light-induced self-healing property of prepared composites was realized through the photo-thermal effect of rmGO. The composite is capable of both structural and electrical healing via NIR irradiation. The injured samples can be locally repaired with high precision and efficiency without an obvious influence on those uninjured parts. The underlying polymer matrix can reform via the dynamic dissociation/recombination of Diels-Alder bonds to bring the separated areas of the AgNWs layer into contact to restore the conductivity. The NIR light-induced self-healing electrically conductive composites have wide potential for many fields, e.g., soft robots, flexible devices, and health-monitoring. [ABSTRACT FROM AUTHOR]

The realization of recyclable materials is an urgent problem to be solved for extending practical applications in industry. Herein, a simple method was proposed to prepared the recyclable materials thorough dynamic reversible chemistry. In this work, we design the recyclable and self-healing polyurethane based on the thermoreversible dynamic Diels-Alder reaction. In addition, the Halloysite nanotubes (HNTs) were introduced into the system to improve the thermal properties, mechanical properties of polyurethane nanocomposites (PUDM/HNTs). The tensile tests showed that the HNTs can significantly improved the mechanical properties of nanocomposites. The healing efficiency above 90% on average was achieved which was determined by the recovery of breaking strength. Besides, the composites exhibited outstanding reprocessability via thermally induced. Therefore, Such excellent recyclable performance and self-healing ability give the polyurethane materials an opportunity to have great potential in the fields of save-energy, friendly-environment materials. Image 1 • The Polyurethane/HNTs nanocomposites show enhanced mechanical and thermal properties. • The polyurethane materials have very high healing efficiency. • The Polyurethane had good thermal self-healing and reprocessability behavior. [ABSTRACT FROM AUTHOR]

We developed a polyurethane material has an excellent self-healing ability as well as mechanical strength. This system was achieved based on dual-crosslinked Diels-Alder (DA) covalent bonding reaction. The first cross-linking point is realized by the DA bonding of polyurethane chain. Because of grafted maleimide group, the maleimide functionalized GO (mGO) sheets can be regarded as analogous cross-linker and provide the second cross-linking point in the system. We investigated and compared the effects of as-produced GO and mGO loading and maleimide functionalization on the mechanical properties and healing efficiency of composites. As a result, compared with those of the pure polyurethane and composites filled with the GO, such maleimide functionalization is found to effectively improve the compatibility between mGO and polymer matrix, increasing mechanical properties and healing efficiency of polyurethane composites. The mechanical properties and healing efficiency of polyurethane can be tuned readily by varying mGO concentration. The healing efficiencies were up to 99% for the nanocomposite containing mGO. These results confirm maleimide functionalization improved dispersion and interfacial interaction between the fillers and the polyurethane matrix. [ABSTRACT FROM AUTHOR]