Search

A series of metal 1, 8, 15, 22-tetraaminophthalocyanines [1, 8, 15, 22-TAPcM, M = Mn(II), Fe(II), Ni(II), Cu(II), Zn(II)] are synthesized and used to chemically modify fluorinated multi-walled carbon nanotubes (F-MWCNTs) with the formation of certain chemical bonds on the surface of carbon nanotubes, and the corresponding composites 1, 8, 15, 22-TAPcM/MWCNTs are obtained. The electrocatalytic activities of the samples are studied by adding them into lithium/thionyl chloride (Li/SOCl2) batteries. The results indicate that the composites 1, 8, 15, 22-TAPcM/MWCNTs can improve the discharge voltage and lengthen the discharge time of the batteries much more than 1, 8, 15, 22-TAPcM, and the order of the electrocatalytic activities of 1, 8, 15, 22-TAPcM/MWCNTs and 1, 8, 15, 22-TAPcM with different metal ions in center is both Mn(II) > Ni(II) > Zn(II) > Fe(II) > Cu(II). It is also found that the discharge time and maximal discharge voltage and capacity for the battery contains 1, 8, 15, 22-TAPcMn/MWCNTs can be improved by 68.19%, 9.41%, and 82.6%, respectively.

Optically transparent poly(methyl methacrylate) (PMMA)-based blends with significantly enhanced mechanical and shape memory properties have been successfully prepared via in-situ formation of micro-scale polylactide stereocomplex crystallites (sc-PLA) in the PMMA matrix in this work. To achieve this goal, a certain content of poly( l -lactide) (PLLA) was firstly melt-blended with PMMA to obtain completely miscible PMMA/PLLA blends, and then an equimolar poly( d -lactide) (PDLA) was incorporated into the blends, giving rise to the in-situ formation of sc-PLA between PLLA and PDLA. In this way, the micro-scale sc-PLA particles were successfully fabricated and homogeneously dispersed in the PMMA matrix. Consequently, these resultant PMMA/sc-PLA blends possess extremely superior optical transparency, even when the content of sc-PLA reaches up to 12 wt%. A further increase in the content of sc-PLA would lead to the formation of sc-PLA network and aggregation, resulting in the deterioration of optical transparency. Moreover, the incorporation of sc-PLA micro-particles significantly enhances the mechanical property of PMMA and the maximum (≈103 MPa) of these blends demonstrates 50% increase than that (≈70 MPa) of PMMA. More importantly, it has been found that the shape recovery performance of PMMA could be effectively improved by the incorporation of sc-PLA. The optimal shape recovery ratio (86%) and high shape fixing ratio (almost 100%) can be obtained for the PMMA/sc12 blend which exhibits excellent optical transparency. It is reasonable to believe that these optically transparent blends with largely enhanced mechanical and shape memory properties possess great application potential in advanced shape memory fields.

It is still a challenge to fabricate polymer-based composites with excellent thermal conductive property because of the well-known difficulties such as insufficient conductive pathways and inefficient filler-filler contact. To address this issue, a synergistic segregated double network by using two fillers with different dimensions has been designed and prepared by taking graphene nanoplates (GNPs) and multiwalled carbon nanotubes (MWCNT) in polystyrene for example. In this structure, GNPs form the segregated network to largely increase the filler-filler contact areas while MWCNT are embedded within the network to improve the network-density. The segregated network and the randomly dispersed hybrid network by using GNPs and MWCNT together were also prepared for comparison. It was found that the thermal conductivity of segregated double network can achieve almost 1.8-fold as high as that of the randomly dispersed hybrid network, and 2.2-fold as that of the segregated network. Meanwhile, much higher synergistic efficiency (f) of 2 can be obtained, even greater than that of other synergistic systems reported previously. The excellent thermal conductive property and higher f are ascribed to the unique effect of segregated double network: (1) extensive GNPs-GNPs contact areas via overlapped interconnections within segregated GNPs network; (2) efficient synergistic effect between MWCNT network and GNPs network based on bridge effect as well as increasing the network-density.

With the extensive use of portable and wearable electronic devices, ultrathin electromagnetic interference (EMI) shielding materials with excellent thermal management are increasingly desirable. In this study, ultrathin and highly aligned reduced graphene oxide (RGO)/cellulose nanofiber (CNF) composite films with excellent EMI shielding performance and strong anisotropy of thermal conductivity were fabricated by vacuum-assisted filtration followed by hydroiodic acid (HI) reduction. The obtained 50 wt% RGO/CNF composite films, which are only ≈23 μm in thickness, possess the remarkable electrical conductivity of ≈4057.3 S m−1 and outstanding EMI shielding effectiveness (SE) of ≈26.2 dB owning to the uniform dispersion and self-alignment into the layered structure of RGO. In addition, the RGO/CNF composite films with 50 wt% RGO loadings possess high in-plane thermal conductivity (K ≈ 7.3 W m−1 K−1) and, unexpectedly, very low cross-plane thermal conductivity (K⊥ ≈ 0.13 W m−1 K−1), resulting in strong anisotropy of the thermal conductivity (K/K⊥ ≈ 56). Thus, these ultrathin RGO/CNF composite films have great application potential as effective lightweight shielding materials against electromagnetic microwaves and heat, especially in flexible portable electronic devices and wearable devices.

Adding conductive filler is an effective way to enhance the dielectric constant while usually also increases the dielectric loss of polymer. In this study, we demonstrated that polymer composites with much improved dielectric constant while maintaining ultra-low dielectric loss could be achieved via using hybrid filler and controlling the dispersion of conductive filler in polymer matrix. To do this, the graphene oxide was designed to be immobilized on the surface of large-sized insulating hexagonal boron nitride (h-BN) via electrostatic self-assembly, and afterwards introducing this hybrid filler into epoxy accompanied with chemical reduction. In this case, since the reduced graphene oxide (rGO) sheets were fixed on the surface of h-BN, rGO sheets were well separated from each other even at high loading. Hence not only significantly enhanced dielectric constant was observed, but also a very low dielectric loss comparable to that of neat epoxy was achieved. This low dielectric loss was believed to be ascribed to both embedded insulating network of h-BN to inhibit the mobility of charge carrier and well-separated rGO sheets via immobilization. In addition to obviously improved dielectric properties, the nanocomposites also exhibited good thermal conductivity. We believe that this special structure will provide a new thought for fabricating dielectric materials with much enhanced dielectric constant as well as well-suppressed dielectric loss.

In this study, we report a sharp increase of both thermal and electrical conductivity in polypropylene (PP) via formation of double percolated filler network with dense small-sized multi-wall carbon nanotubes (MWCNT) network located within loosened large-sized expanded graphite (EG) network. The electrical conductivity of PP/EG composites which levels off after the percolation threshold can be further enhanced by adding MWCNT and is increased two orders of magnitude as the content of MWCNT reaches to its threshold. Besides, the thermal conductivity of PP/EG-MWCNT increases by 38.5% compared to PP/EG and is much higher than PP/MWCNT. Furthermore, an excellent electromagnetic interference shielding effectiveness of ∼60 dB is obtained at the sample thickness of only 1.3 mm. Then, effective medium theory model is applied to analyze the mechanism for the largely enhanced thermal and electrical conductivity. It is suggested that formation of double percolated filler network, in which three types of connections exist between EG and EG, EG and MWCNT as well as MWCNT and MWCNT, could effectively reduce the interface thermal resistance. Our work is important and provides some new idea for the preparation of polymer composites with excellent thermal and electrical conductivity via constructing double percolated filler network.

In this work, super strong all-cellulose multifilaments were obtained from cellulose dissolved in LiOH/urea system by inducing nanofiber formation, and were simultaneously reinforced by the introduction of TEMPO-oxidized nanofibrillated cellulose (NFC) with mean diameter of 20 nm. The all-cellulose composite filaments (CF) containing only 3 wt % NFC exhibits a high orientation that Herman's parameter is 0.89. Importantly, the NFC can simultaneously reinforce and toughen the CF, with a tensile strength and elongation at break of 3.92 cN/dT and 14.6%, respectively, which make the obtained CF to become super strong. The strengthened mechanism of CF is considered as the nanofibril-induced crystallization and orientation, which makes up for the deficits and constructs a flawless structure in the regenerated cellulose filaments. Of note, the stability of spinning dope was also effectively improved by adding small amount of NFC, which is very important for fiber spinning on industry. This finding contributes to the preparation of high performance regenerated cellulose multifilaments by a simple, energy-efficient, and eco-friendly route.

Herein, a small amount of cellulose nanofiber (CNF) was introduced in graphene oxide (GO) spinning dope to improve the property of graphene fiber. It was found that the one-dimensional CNF could absorb on the GO sheets, and enhance the inter-layer interaction as well as the connection between GO sheets, resulting in an easy formation of lyotropic liquid crystalline structure and a better orientation of the resultant fiber. A large enhancement of tensile strength, modulus, and elongation of GO/CNF hybrid fiber has been achieved. After chemical reduction of GO, the fiber still maintains its original mechanical properties but with high conductivity and improved hydrophilicity. Our work further demonstrates the importance of a stable lyotropic liquid crystalline structure of GO dope in the spinning of graphene fiber and provides a facile way to produce graphene fiber with good performance.

It has been demonstrated that introducing another non-conductive particle into conductive filler filled composites could result in a better conductivity due to a volume exclusion effect. It was also reported that combining electrically conductive fillers with different geometric shapes and aspect ratio together could enhance the electrical conductivity due to the synergistic effect. To further explore these two effects on the electrical property enhancement, we firstly encapsulated neat silica (SiO2) with graphene oxide (GO) through electrostatic self-assembly to render SiO2 with surface conductivity. Then neat SiO2 or SiO2@GO together with multi-walled carbon nanotubes (MWCNT) were mixed with polystyrene (PS) to prepare conductive composites. In this way, the volume exclusion effect in the PS/MWCNT/SiO2 system and combined effect of volume exclusion and synergy in the PS/MWCNT/SiO2@rGO system could be investigated and compared. An obvious increased conductivity was observed only in the transition composition region for the PS/MWCNT/SiO2 system compared with the PS/MWCNT system. However, a largely enhanced conductivity was achieved through the composition region for the PS/MWCNT/SiO2@rGO system compared with the PS/MWCNT/SiO2 system and PS/MWCNT, accompanied by great enhancement of the electromagnetic interference (EMI) shielding effectiveness. Given the SEM characterization and rheological properties, we attributed this obvious enhanced electrical property to both a volume exclusion effect and a synergistic effect.

A series of metal 2,9,16,23-tetraaminophthalocyanines [TAPcM, M = Cu(II), Ni(II), Zn(II), Fe(II), Mn(II)] have been prepared and used to chemically modify fluorinated multi-walled carbon nanotubes (F-MWCNTs). The generated composites TAPcM/MWCNTs were characterized by IR, UV-Vis and XRD. The electrocatalytic activity of all the composites was evaluated by adding them into the electrolyte of the Li/SOCl2 battery and taking cyclic voltammograms in simulated circumstances. The results show that the composites can dramatically improve the capacity of the battery, and their electrocatalytic performance strongly depends on the metal phthalocyanine species. The order of the electrocatalytic activity of 2,9,16,23-TAPcM and 2,9,16,23-TAPcM/MWCNTs with different metal ions in the center is Mn(II) > Ni(II) > Zn(II) > Fe(II) > Cu(II). The excellent electrocatalytic performance of the modified F-MWCNTs may be due to the fine synergistic effect between the metal phthalocyanines and the MWCNTs.

Autonomously self-healing hydrogels have received considerable attentions due to their capacity for repairing themselves spontaneously after suffering damage, which can provide a better stability and a longer life span. In this work, a robust and mechanically and electrically self-healing hydrogel with an efficient electromagnetic interference (EMI) shielding performance was successfully fabricated via the incorporation of multiwalled carbon nanotubes (MWCNTs) into the hydrophobically associated polyacrylamide (PAM) hydrogels by using cellulose nanofiber (CNF) as the dispersant. It was been found that CNF could not only assist the homogeneous dispersion of MWCNTs but also effectively enhance the mechanical property of the resultant hydrogels. As a result, the optimal tensile strength (≈0.24 MPa), electrical conductivity (≈0.85 S m–1), and EMI shielding effectiveness (≈28.5 dB) were achieved for the PAM/CNF/MWCNT composite hydrogels with 1 wt % MWCNTs and 0.3 wt % CNF, which showed 458, 844, and 90% increa...

Hydrophobically associated (HA) hydrogels have attracted great concerns with their admirable properties, such as self-healing and shape memory. However, a few works have been devoted to apply HA hydrogels in practice, especially in wastewater treatment. This may be because of the non-ionic monomer composition and the poor mechanical properties after swelling. In this work, in order to improve the mechanical properties and absorption behavior of HA polyacrylamide (HPAM) hydrogel, hydrophobically associated polyacrylamide/cellulose nanofiber (HPAMF) composite hydrogels were prepared. It was found that by incorporating CNF (2 wt%), the tensile strength (≈0.276 MPa) was largely increased by 632% compared to HPAM hydrogels. The maximum Cu ion adsorption capacity of the HPAMF hydrogel (containing 2 wt% CNF) was 2.33 mmol g−1, about 86% over the HPAM hydrogel. The HPAMF hydrogels with self-healing, excellent mechanical and adsorption properties can be promisingly served as reliable absorbents, consequently satisfying the needs of practical application of heavy metal treatment.

Tyro3, a member of the Tyro3/Axl/Mer (TAM) family of receptor tyrosine kinases, has emerged as a potential oncogene in melanoma. Here, we confirm that Tyro3 is specifically overexpressed in primary melanoma samples and show that Tyro3 is expressed at varying levels in numerous melanoma cell lines. Short hairpin RNA-mediated knockdown of Tyro3 led to significant cell death via apoptotic mechanisms in nearly all melanoma cell lines tested, regardless of the BRAF or NRAS mutation status or co-expression of Axl and/or Mer. We generated soluble and monomeric versions of the human Tyro3 extracellular domain and human Gas6 for affinity measurements and correlated these values with the level of Gas6 required to induce Tyro3 signaling in cellular assays. Calcium was critical for the correct folding of Gas6 and its binding to Tyro3. In melanoma cell lines, Gas6 induced Tyro3 phosphorylation and downstream Akt phosphorylation without apparent effects on Erk. We generated monoclonal antibodies (mAbs) against Tyro3 to examine their effect on survival signaling in melanoma cell lines. The mAbs generated against Tyro3 included nonligand blockers, partial blockers, and competitive ligand blockers. A number of weak and partial ligand blockers (all recognizing the Tyro3 Ig domains) were the most effective at blocking ligand-mediated downstream signaling of Tyro3. Overall, these data indicate that Tyro3 may confer increased survival signals in melanoma cells and can be stymied using inhibitory mAbs. These mAbs may be useful for further investigations of the role of Tyro3 in melanoma.

Interleukin-8 modulation is implicated in many inflammatory and cancer diseases. Starting from a mass-screening hit, the synthesis and structure-activity relationship of 2-amino-3-heteroarylquinoxalines as non-peptide, small molecule interleukine-8 receptor antagonists have been developed. The optimized derivatives, PD 0210293 (13y) and PD 0220245 (13r), show inhibition of both IL-8 receptor binding and IL-8-mediated neutrophil chemotaxis.

A series of zinc–flavonolate complexes of the general formula [(L)Zn(R)]ClO4 (L = TPA (tris-2-(pyridylmethyl)amine)), 6-MeTPA (N,N-(6-methyl-2-pyridyl)methyl)bis(2-pyridylmethyl)amine)), 6-Me2TPA (N,N-bis(6-methyl-2-pyridyl)methyl)(2-pyridylmethyl) amine), BPQA (bis(2-pyridylmethyl)(2-quinolinemethyl)amine), and BQPA (bis(2-quinolinemethyl)(2-pyridylmethyl)amine), R = FLH (flavonol), 4-MeOFLH (4-methoxyflavonol), and 4-MeOFLTH (4-methoxyflavothione)) have been prepared and characterised by X-ray crystallography, elemental analysis, FT-IR, ESI-MS, 1H NMR, 13C NMR, UV-vis and fluorescence spectroscopy. All the complexes can be induced to release CO by visible light (λmax ranges from 414 to 503 nm). The maximum absorption wavelength of the complexes followed the order 4-MeOFLTH > 4-MeOFLH > FLH. Exposure of the complexes to visible light under aerobic conditions results in oxidative C–C bond cleavage and almost quantitative CO release. Cytotoxicity tests showed that the complexes had a low toxicity to HeLa cells in the concentration range of 1 to 50 μM. These advantages indicate that the series of complexes are likely to be applied to biological systems.

The Nogo66 receptor (NgR1) is a neuronal, leucinerich repeat (LRR) protein that binds three central nervous system (CNS) myelin proteins, Nogo, myelin-associated glycoprotein, and oligodendrocyte myelin glycoprotein, and mediates their inhibitory effects on neurite growth. Although the LRR domains on NgR1 are necessary for binding to the myelin proteins, the exact epitope(s) involved in ligand binding is unclear. Here we report the generation and detailed characterization of an anti-NgR1 monoclonal antibody, 7E11. The 7E11 monoclonal antibody blocks Nogo, myelin-associated glycoprotein, and oligodendrocyte myelin glycoprotein binding to NgR1 with IC50 values of 120, 14, and 4.5 nm, respectively, and effectively promotes neurite outgrowth of P3 rat dorsal root ganglia neurons cultured on a CNS myelin substrate. Further, we have defined the molecular epitope of 7E11 to be DNAQLR located in the third LRR domain of rat NgR1. Our data demonstrate that anti-NgR1 antibodies recognizing this epitope, such as 7E11, can neutralize CNS myelin-dependent inhibition of neurite outgrowth. Thus, specific anti-NgR1 antibodies may represent a useful therapeutic approach for promoting CNS repair after injury.