The latest generation of wearable devices features materials that are flexible, conductive, and stretchable, thus meeting the requirements of stability and reliability. However, the metal conductors ...that are currently used in various equipments cannot achieve these high performance expectations. Hence, a mussel‐inspired conductive hydrogel (HAC–B–PAM) is prepared with a facile approach by employing polyacrylamide (PAM), dopamine‐functionalized hyaluronic acid (HAC), borax as a dynamic cross‐linker agent, and Li+ and Na+ as conductive ions. HAC–B–PAM hydrogels demonstrate an excellent stretchability (up to 2800%), high tensile toughness (42.4 kPa), self‐adhesive properties (adhesion strength to porcine skin of 49.6 kPa), and good self‐healing properties without any stimuli at room temperature. Furthermore, the fabricated hydrogel‐based strain sensor is sensitive to deformation and can detect human body motion. Multifunctional hydrogels can be assembled into flexible wearable devices with potential applications in the field of electronic skin and soft robotics.
Inspired by the adhesion of natural mussels, the synthesized hydrogel exhibits self‐adhesion (adhesion strength to porcine skin of is up to 49.6 kPa), good self‐healing (within 1 h), and high strain sensitivity. It meets the flexibility and stability requirements of the latest generation of wearable devices to detect human body movements.
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•The high value-added POPs derived from the waste-expanded polystyrene was prepared.•The POPs exhibited tunable pore sizes, abundant micro/mesoporous structure and high surface ...areas.•The POPs possessed excellent adsorption performance to antibiotics and chlorophenols.•The costs of POPs are much lower than that of commercial ACs (GAC1240).
Increasing evidence has shown that plastic pollution and water contamination are serious environmental issues. Herein, by utilizing cheap, abundant waste expanded polystyrene (EPS) as the raw material, high-value-added porous organic polymers (POPs) were prepared through a Friedel–Crafts alkylation reaction using two types of cross-linkers and applied to the removal of antibiotics and chlorophenols. The structural characterization indicated that the pore structure of the two types of POPs (EPS-FDA and EPS-CC) can be successfully tuned by stepwise crosslinking with dimethyl acetal (FDA) and introducing different doses of cyanuric chloride (CC) as a cross-linker. Notably, EPS-FDA and EPS-CC have high specific surface areas with abundant micro/mesoporous structures. The maximum adsorption capacity of EPS-FDA-2 for TC removal (calculated by the Langmuir model) can reach 621.12 mg·g−1, and the amount of 2,4-DCP on EPS-CC-3 is up to 680.27 mg·g−1. Moreover, possible adsorption mechanisms including pore filling and π–π electron interactions are discussed. Hydrogen bonding also plays a role in the removal process of 2,4-DCP by EPS-CC-3. This study developed a novel and green synthetic method for the efficient recycling of waste plastics and demonstrated an industrialized approach for conversion of waste plastics into high-value-added adsorbing material, which could be a promising candidate for the removal of organic contaminants.
This work aims at developing a customized ammoxidation catalyst through optimizing the metal oxide content in CrVO
4
/SiO
2
catalysts. Various amounts of Cr–V–O with 1:1 molar ratio of Cr/V were ...successfully loaded on SiO
2
via spray-drying method with colloidal silica as the binder. Polarized light microscope illustrated that the CrVO
4
/SiO
2
particles presented as well dispersed microspheres in the microsize (20–80 μm). X-ray diffraction spectra confirmed the formation of monoclinic CrVO
4
phase wherein the metal oxide content was ranged from 30 to 70 weight percent. FT-IR spectra indicated that the introduction of metal oxide had no obvious effects on the skeletal structure of SiO
2
. X-ray photoelectron spectroscopy analysis revealed that the valence state of V and Cr was hardly affected with increasing the metal oxide content. Performances of the obtained CrVO
4
/SiO
2
catalysts with different metal oxide contents were investigated via the ammoxidation of a model compound, namely para-chlorotoluene (PCT) to para-chlorobenzonitrile (PCBN). A maximum conversion of 99.6% of PCT and 86.5% yield and 86.8% selectivity to PCBN have been obtained over the CrVO
4
/SiO
2
catalyst with 60% weight of metal oxides at a temperature of 410 °C,
n(
PCT):
n
(NH
3
):
n
(air) = 1:3:15 and reaction load = 0.13 g/gCat·h. In addition, this catalyst was efficient and selective toward ammoxidation reactions of toluene, ortho- and meta-chlorotoluenes.
Graphical abstract
Vanadium phosphorus oxide (VPO) was immobilized on SBA-15 via a facile impregnation process. The structure and VPO species on SBA-15 were characterized by XRD, TEM, BET, FTIR and XPS techniques. It ...was found the VPO/SBA-15 catalysts maintained the two-dimensional hexagonal structure of SBA-15, and the supported VPO species existed in a highly dispersed amorphous state. VPO/SBA-15 catalyst was tested for the ammoxidation of dichlorotoluenes (DCTs) to corresponding dichlorobenzonitriles (DCNs) in a lab-scale tube reactor. Compared with VPO/SiO
2
(large-pore silica-supported VPO), VPO/SBA-15 exhibited appreciable enhancement in the catalytic performance due to the unique channel structure of SBA-15. The yield and selectivity toward 2,4-DCN increased by 7% and 6%, while toward the sterically hindered 2,6-DCN increased by 7% and 13%, respectively.
Graphical abstract
Formulation and shaping of heterogeneous catalysts are vital in the successful industrial application. Here micro-sized vanadium chromium composite oxides catalysts with the spherical shape were ...prepared via spray drying with colloidal silica as a binder material. The physicochemical properties of catalysts with different Cr/V molar ratios were characterized by XRD, XPS, FT-IR, TPR, and particle size distribution analysis. It was revealed that the addition of Cr inhibited the formation of the crystalline phase V
2
O
5
and decreased the reduction temperature of pentavalent vanadium species, and also resulted in the formation of monoclinic CrVO
4
and a highly dispersed state of vanadia species. VCrO/SiO
2
particles with various Cr/V atomic ratio were studied as catalysts for
p
-chlorotoluene ammoxidation to
p
-chlorobenzonitrile, in which the catalyst with Cr/V ratio of 1 exhibited the best catalytic performance. When the Cr/V ratio was less than 1, mixed phases of orthorhombic CrVO
4
and monoclinic Cr
2
V
4
O
13
were formed and resulted in a low catalytic activity. With the increase of Cr/V ratio, the content of monoclinic CrVO
4
in the catalysts increased, resulting in the catalytic activity of the catalysts improved. However, too large an amount of Cr led to the formation of highly oxidizing hexagonal-Cr
2
O
3
phase, which reduced the selectivity of the catalytic reaction.
Graphic abstract
P
-
Phenyl-bridged bis-salicylaldiminato binuclear titanium complexes
Ti
2
L
1
,
Ti
2
L
2
and the corresponding momonuclear counterpart
TiL
4
were synthesized and characterized by
1
H NMR,
13
C NMR, ...FT-IR, and elemental analysis. The binuclear titanium complex
Ti
2
L
1
showed good catalytic performances for ethylene polymerization and copolymerization with norbornene or 1,5-hexadiene. For ethylene polymerization, the binuclear titanium complex
Ti
2
L
1
exhibited highest activity of 8.70 × 10
5
g/mol(Ti)
.
h
.
atm at 70 °C and retained an activity of 3.00 × 10
5
g/mol(Ti)
.
h
.
atm at 90 °C, which showed much higher thermal stability compared with its bi- and mono-nuclear derivatives
Ti
2
L
3
and
TiL
4
,
due probably to the rigid phenyl-bridged structure offering more stable state of active metal centers. The binuclear complex
Ti
2
L
1
could catalyze ethylene copolymerization with norbornene (NB) or 1,5-hexadiene (1,5-HD) to produce copolymer bearing cyclic groups. Compared with mononuclear complex
TiL
4
, the binuclear
Ti
2
L
1
showed higher catalytic activity and incorporation rate of comonomer for ethylene/NB copolymerization. The mononuclear complex
TiL
4
could barely catalyze the copolymerization of ethylene and 1,5-HD, however, the binuclear analogue
Ti
2
L
1
exhibited an activity of 1.67 × 10
5
g/mol(Ti)·h·atm with 4.74% of incorporation rate of 1,5-HD for ethylene/1,5-HD copolymerization, implying that the bimetallic synergistic effect could greatly improve the catalytic performance of the bis-salicylaldiminato binuclear titanium complexes.
Dichlorobenzonitriles are important organic intermediates for the production of many fine chemicals and are produced most economically and environment-friendly in industry by ammoxidation of ...dichlorotoluenes. In this paper, 2,4-dichlorobenzonitrile were prepared by direct ammoxidation of 2,4-dichlorobenzyl chloride with higher yield at much lower reaction temperature compared with ammoxidation of 2,4-dichlorotoluene, which proved that the multi-chlorobenzyl chlorides could be successfully ammoxidized to corresponding benzonitriles. Subsequently, a novel route for efficient preparation of 2,5-dichlorobenzonitrile was developed by chloromethylation of
p
-dichlorobenzene first, followed by catalyzed ammoxidation of the 2,5-dichlorobenzyl chloride. The products were confirmed by
1
H NMR, MS, and elemental analysis with a total yield of 67%. This is the first case to prepare 2,5-dichlorobenzonitrile by catalytic gas-phase ammoxidation and also afforded a simple and economical approach for preparation of multi-chlorobenzonitriles.
Graphical Abstract
By using the low loading of the conductor filler to achieve high conductivity is a challenge associated with electrically conductive adhesion. In this study, we show an assembling of nickel-coated ...polystyrene (Ni@PS) microspheres into 3-dimensional network within the epoxy resin with the assistance of an electric field. The morphology evolution of the microspheres was observed with optical microscopy and scanning electron microscopy (SEM). The response speed of Ni@PS microsphere to the electric field were investigated by measuring the viscosity and shear stress variation of the suspension at a low shear rate with an electrorheological instrument. The SEM results revealed that the Ni@PS microspheres aligned into a pearl-alike structure. The AC impedance spectroscopy confirmed that the conductivity of this pearl-alike alignment was significantly enhanced when compared to the pristine one. The maximum enhancement in conductivity is achieved at 15 wt. % of Ni@PS microspheres with the aligned composites about 3 orders of magnitude as much as unaligned one, typically from ~10−5 S/m to ~10−2 S/m.
A novel tandem catalysis system consisted of salicylaldiminato binuclear/mononuclear titanium and 2,6-bis(imino)pyridyl iron complexes was developed to catalyze ethylene in-situ copolymerization. ...Linear low-density polyethylene (LLDPE) with varying molecular weight and branching degree was successfully prepared with ethylene as the sole monomer feed. The polymerization conditions, including the reaction temperature, the Fi/Ti molar ratio, and the structures of bi- or mononuclear Ti complexes were found to greatly influence the catalytic performances and the properties of obtained polymers. The polymers were characterized by differential scanning calorimetry (DSC), high temperature gel permeation chromatography (GPC) and high temperature
C NMR spectroscopy, and found to contain ethyl, butyl, as well as some longer branches. The binuclear titanium complexes demonstrated excellent catalytic activity (up to 8.95 × 10
g/molTi·h·atm) and showed a strong positive comonomer effect when combined with the bisiminopyridyl Fe complex. The branching degree can be tuned from 2.53 to 22.89/1000C by changing the reaction conditions or using different copolymerization pre-catalysts. The melting points, crystallinity and molecular weights of the products can also be modified accordingly. The binuclear complex
with methylthio sidearm showed higher capability for comonomer incorporation and produced polymers with higher branching degree and much higher molecular weight compared with the mononuclear analogue.
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