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An electron donor-acceptor complex-enabled, nickel-catalyzed three-component net-reductive 1,2-alkylacylation of alkenes is developed. This conjunctive reductive acyl cross-coupling process obviates the use of an exogenous photocatalyst and a stoichiometric metal-based reductant, affording various synthetically useful 1,3-dicarbonyl compounds in good yields with a broad substrate scope and excellent functional group tolerance. Both alkyl and acyl electrophiles are derived from the highly abundant and readily accessible carboxylic acids, making the catalytic 1,2-dicarbofunctionalization more synthetically general and sustainable.

Lithium–sulfur batteries (LSBs) have drawn tremendous attention for their superior theoretical energy density. Nevertheless, the “shuttle effect” originating from the dissolution and migration of l...

Endowing conductive composites with good self-healing properties is of great significance for improving the stability and extending the service life of the material. However, it is still a challenge to prepare conductive composites that exhibit both desirable mechanical strength and excellent self-healing properties. Herein, we report a simple method to fabricate a kind of material with excellent self-healing properties and satisfactory mechanical strength and conductivity performance. Nanochitin (CNC), carboxymethyl chitosan (CMCS), and carbon nanotubes (CNTs) were used as reinforcing fillers and filled into epoxidized natural rubber (ENR) through latex mixing. In particular, CNCs, CMCS, and CNT fillers were selectively dispersed among ENR latex particles. A filler frame network structure based on multiple hydrogen bonding interactions was constructed in the rubber matrix, which significantly improved the mechanical and electrical properties of the composites. Furthermore, the formation of multiple hydrogen bonds in the composites endowed the rubber with excellent self-healing properties, achieving the highest healing efficiency of 91%. This work provides a novel and simple strategy to prepare conductive composites with excellent mechanical and self-healing properties.

With extremely high theoretical energy density, lithium–sulfur (Li–S) batteries have attracted abundant interest as a promising next-generation energy storage device. Polymer binders as an ingredie...

In this work, a new type of metal-organic coordination polymer (MOP) was developed with thermoplastic starch (TPS) by reactive extrusion with zinc acetate (ZA). The resulting material, denoted as T...

Recyclable polyvinylidene fluoride/silicone rubber (PVDF/SR) thermoplastic vulcanizates (TPVs) containing high mass ratio of SR (50%) with excellent mechanical performances and shape memory behavio...

Blending with elastomers is one of the most effective strategies for toughening polylactide (PLA), but faces the challenge of a sharp decline in stiffness. In this work, PLA/epoxidized natural rubb...

At present, achieving recycling of rubbers is the main method for their sustainable development. However, it is a challenge to recycle rubbers without retained pristine reinforcing-fillers. Herein, we report fully bio-based rubber films prepared by mixing epoxidized natural rubber (ENR) latex and carboxymethyl chitosan (CMCS) solution. CMCS was regenerated and selectively located in the interstitial space between the ENR latex particles during film-forming process, forming a CMCS framework network in the films. The special CMCS network with hydrogen bonding interactions with ENR endowed rubber films with improved mechanical properties. At the same time, the self-sticky characteristic of ENR with the assistance of chain diffusion and reversible hydrogen bonding interactions made the cut films to be welded. Because the water-soluble CMCS is a continuous phase, the ENR could be perfect recycled by soaking films in water to remove the CMCS. Furthermore, the CMCS framework running through the whole films, whic...

Self-healing based on noncovalent bonds and mechanical strengthening based on fillers are contradictions for commercial rubbers. To solve this problem, in this paper, we constructed a hydrogen bond...

To expand the application of shape memory materials in situations where elevated temperature and corrosion resistance are required, novel heat-triggered shape memory (HSM) fluorosilicon thermoplast...

The fabrication of SBS-g-COOH/ZnO composites cross-linked by Zn2+ salt-bondings was reported. First, SBS-g-COOH with different grafting ratio was synthesized through the thermally induced thiol–ene...

In this work, nitrile rubber (NBR) with high strength and recycling ability was designed based on the interaction between metal ions and ligands. Herein, we first epoxidized the nitrile rubber late...

In this work, multi-stimuli-responsive shape memory PLA/epoxidized natural rubber (ENR)/ferriferrous oxide (Fe3O4) thermoplastic vulcanizates (TPVs) with balanced stiffness–toughness were designed via dynamic vulcanization. Regulated by thermodynamic factors and kinetic factors, Fe3O4 was selectively distributed in the continuous ENR phase or at the PLA/ENR interface, which played a crucial role in reinforcing rubber and interfacial compatibilization. Therefore, excellent multi-stimuli-responsive shape memory behavior and significantly improved impact strength were achieved without decreasing its tensile strength. With 30 phr Fe3O4, impact strength reached 90.08 kJ/m2 (without fracture), which was 31 times that of neat PLA. Meanwhile, the TPVs could recover their original shape in merely several seconds along with the shape recovery ratio of 96.63% in the thermal field. Additionally, Fe3O4 also endowed the TPVs with a magnetic-/light-induced shape memory effect in an alternating magnetic field and under t...

We designed novel self-healing thermoplastic vulcanizates (TPVs), achieving excellent thermal/magnetic/light-triggered shape memory assisted self-healing behavior. Damage on polylactide (PLA)/epoxidized natural rubber (ENR)/Fe3O4 TPVs could be healed via three events synergistically: the shape memory effect of TPVs resulted in the physical contact of damaged surfaces; the desorption–absorption of ENR/Fe3O4-bound rubber promoted interdiffusion of ENR chains, leading to the self-healing of ENR phase; ENR was grafted onto PLA segments to assist PLA rearranging and entangling again to achieve the repair of TPVs. This self-healing TPV is reported for the first time and paves the way to design next-generation self-healing materials.

Cellulose nanocrystals have been proved to be ideal reinforcing fillers for rubber. However, the increase in tensile strength always accompanies a reduction in extensibility. In this paper, epoxidi...

Stiffness and toughness are two mutually exclusive attributes of polymer materials that contribute to significant improvements in impact strength, usually accompanied by a reduction in tensile strength. In this study, ternary thermoplastic vulcanizates (TPVs) consisting of poly(lactic acid) (PLA), poly(methyl methacrylate)-grafted natural rubber (NR-PMMA), and natural rubber (NR) with balanced stiffness and toughness were successfully prepared via peroxide-induced dynamic vulcanization. With 10 wt% of NR and NR-PMMA, the PLA/NR-PMMA/NR ternary TPV displayed an enhanced yield stress of 41.7 MPa (only 38% loss compared to neat PLA) and a significantly higher impact strength of 91.30 kJ/m2 (nearly 32 times that of neat PLA). The in situ compatibilization between PLA and rubber phases was confirmed by Fourier transform infrared spectroscopy. Interfacial, rheological, and calorimetric measurements confirmed that the NR was encapsulated by NR-PMMA in the PLA phase. It was found that the flexibility of the “soft...

In most cases, the strength of self-healing supramolecular rubber based on noncovalent bonds is in the order of KPa, which is a challenge for their further applications. Incorporation of conventional fillers can effectively enhance the strength of rubbers, but usually accompanied by a sacrifice of self-healing capability due to that the filler system is independent of the reversible supramolecular network. In the present work, in situ reaction of methacrylic acid (MAA) and excess zinc oxide (ZnO) was realized in natural rubber (NR). Ionic cross-links in NR matrix were obtained by limiting the covalent cross-linking of NR molecules and allowing the in situ polymerization of MAA/ZnO. Because of the natural affinity between Zn2+ ion-rich domains and ZnO, the residual nano ZnO participated in formation of a reversible ionic supramolecular hybrid network, thus having little obstructions on the reconstruction of ionic cross-links. Meanwhile, the well dispersed residual ZnO could tailor the mechanical properties...

Fe3O4-based magnetic rubbers are desirable because they take advantage of high elasticity, large elongations, and high magnetic saturation intensity of each component. However, direct compounding of rubbers and Fe3O4 usually resulted in low mechanical properties which made the magnetic rubbers unable to satisfy practical applications. In this paper, we prepared nitrile butadiene rubber (NBR)/Fe3O4-based magnetic rubbers with good mechanical properties by means of in situ compatibilization using zinc dimethacrylate (ZDMA). Our strategy was based on the polymerization of ZDMA during a peroxide-induced vulcanization, in which the polymerized ZDMA (PZDMA) brought massive Zn2+ ion pairs into NBR. Zn2+ ion pairs not only increased the polarity of NBR but also strongly interacted with Fe3O4 nanoparticles. Because of the graft-PZDMA, the Zn2+ ion pairs finally strengthened interactions between Fe3O4 nanoparticles and NBR molecules. We hope this report laid an applied foundation for design of high performance magn...

Constructing a reversible supramolecular network cross-linked by noncovalent bonds is an effective approach to realize self-healing as well as reprocessing and recycling for rubbers. Unfortunately, in most case the resultant noncovalent cross-linked rubbers cannot hold enough forces to meet the routine applications. In this paper, our strategy was based on a simple reaction between carboxy groups in carboxylated styrene butadiene rubber (XSBR) and zinc oxide (ZnO), where the formed Zn2+ salt bondings connect separate XSBR molecules. The further self-aggregation of ion pairs of Zn2+ salts resulted in an ionic cross-linked network, whose rearrangements brought XSBR excellent reprocessing/recycling ability. Additionally, the reclaimed XSBR exhibited valuable mechanical properties due to the compensation of additional formed new Zn2+ salt bondings during recycling. The fresh XSBR with 5 wt % zinc oxide showed a tensile strength of 6.7 MPa, and it was further increased to 10.3 MPa after 3 recycles, which was f...

Ethylenepropylenediene rubber/polypropylene (EPDM/PP) thermoplastic vulcanizates (TPVs) are the most commercial general thermoplastic elastomers with a substantial cost advantage. Through suitable interface modification, new functional application can be brought to EPDM/PP TPVs. In this study, we present a shape memory polymer (SMP) derived from an EPDM/PP TPV in which the phase interface was strongly enhanced by zinc dimethacrylate (ZDMA). ZDMA-induced in situ compatibilization provided assistance in deforming or keeping the deformed rubber particles in temporary shape, storing sufficient resilience to well fulfill the shape memory effect (SME) of EPDM/PP TPVs. The PP phase served as a “container” to fix the deformation status of rubber particles via the enhanced interface. The incorporation of ZDMA significantly reduced the size of rubber particles, consequently increasing the contact areas between the EPDM and PP phases, which contributed to the SME. The shape memory behavior of EPDM/PP/ZDMA TPVs was c...

Herein, we report a new method, core–shell dynamic vulcanization, to prepare a poly(vinylidene fluoride) (PVDF)-based thermoplastic vulcanizate (TPV) with cross-linking-controlled silicone rubber (SR)/fluororubber (FKM) core–shell particles. The bicrosslinked SR-core/FKM-shell structure effectively stabilized the blending morphology of TPV, avoiding the direct contact of PVDF and SR. Results of transmission electrom microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier transform-infrared (FT-IR) confirmed the formation of core–shell structure. In the PVDF/FKM/SR (40/30/30) TPV, the size of core–shell particle was ∼2 μm, and the thickness of the FKM shell was ∼400 nm. The cross-link density of SR-core and FKM-shell could be controlled to tailor the properties of the TPV. It was found that the tan δ value of core–shell bicrosslinked TPV could be maintained at around 0.3 in range of 1–1000 cpm. The TPV exhibited good mechanical properties in which its tear strength ...

Shape memory polymers (SMPs) based on fully biobased poly(lactide) (PLA)/natural rubber (NR) thermoplastic vulcanizates (TPVs) were fabricated via peroxide-induced dynamic vulcanization. Simultaneously, in situ reactive compatibilization was achieved by PLA molecule grafting onto NR chains. Differing from the general concept of spherical rubber particles being formed after dynamic vulcanization, the cross-linked NR was found to be a “netlike” continuous phase in the PLA matrix. This novel structure explained the surprising shape memory property of PLA/NR TPVs well (shape fixities ∼ 100%, shape recoveries > 95%, and fast recovery speed < 15 s at the switching temperature, ∼60 °C): the cross-linked NR continuous phase offers strong resilience and the PLA phase serves as the heat-control switch. We envision that the “green” raw materials and excellent shape memory properties of the dynamically vulcanized PLA/NR SMPs will open up a wide range of potential applications in intelligent medical devices.

A biobased heat-triggered shape-memory polymer (HSMP) consisting of polylactide (PLA) and epoxidized natural rubber (ENR) was fabricated by peroxide-induced dynamic vulcanization. The cross-linked ENR phase exhibits a continuous net-like structure embedded in the PLA phase, which is different from a conventional plastic/rubber system having the typical “sea–island” morphology in which vulcanized rubber particles were dispersed in plastic matrix. In situ interfacial compatibilization was confirmed by FTIR analysis. The shape-recovery ratios of the PLA/ENR HSMPs were significantly improved over 90%, compared to that (60–70%) of PLA. The shape fixing and memorizing capability of PLA/ENR HSMPs was realized by the glass transition of the PLA phase: cross-linked ENR continuous phase at rubbery state offered strong recovery driving force, improved interface provided effective stress-transferring during shape recovery, and PLA continuous phase served as a “control-switch” for recovery. The biobased PLA/ENR HSMP c...

This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using zinc dimethacrylate (ZDMA) as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With the incorporation of 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength, tear strength, elongation at break, and hardness of PP/EPDM/ZDMA TPV were increased from 5.3 MPa, 31.3 kN/m, 222%, and 78 up to 11.2 MPa, 64.2 kN/m, 396%, and 83, respectively. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacted with EPDM and PP during peroxide-induced dynamic vulcanization. A peculiar phase structure that rubber particles were surrounded and "bonded" by a thick transition zone that contained numerous of nanoparticles with dimensions of about 20-30 nm was observed from transmission electron microscopy. Scanning electron microscopy results confirmed that incorporation of ZDMA reduced the size of the cross-linked EPDM particles. Moreover, we found that the compatibilized TPV showed a higher tan δ peak temperature for EPDM phase and a lower tan δ peak temperature for PP phase. The suggested method for in situ reactive compatibilization of PP and EPDM offers routes to the design of new TPV-based technical products for diversified applications.

Polypropylene (PP)/ethylene-propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blend (EPDM/PP ratio of 30/70) with remarkable extensibility was successfully prepared via peroxide dynamic vulcanization. The uniaxial tensile properties, crystallization behavior, structure, and morphology during stretching were investigated. The tensile process study showed that the PP/EPDM/ZDMA blend exhibited the rubbery-like behavior with an elongation beyond 600%. The ZDMA graft-product domain increased the compatibility and interfacial adhesion between rubber and PP phases, while it reduced the crystallinity of the PP phase. On the basis of TEM and SEM analyses, we found that the cross-linked rubber particles could be elongated and oriented along the tensile direction, whereas the ZDMA graft-product domain "encapsulated" rubber phase together, acting as a "bridge" between elongated rubber phases and the PP phase during uniaxial stretching. The stress could be effectively transferred from the PP phase to the numerous elongated rubber phases due to the excellent compatibility and interfacial adhesion between rubber and PP phases, resulting in the rubbery-like behavior.