We synthesized a novel amphiphilic alternating copolymer brush (AACPB), poly{maleimide-g-poly10-(cholesteryloxycarbonyl)decyl methacrylate}-alt-(styrene-g-poly(ethylene oxide)) ...(P(MI-g-PCholMA)-alt-(St-g-PEO)), by copolymerization of maleimide-terminated poly10-(cholesteryloxycarbonyl)decyl methacrylate (MI-PCholMA) and styrene-terminated poly(ethylene oxide) (St-PEO). The thermal properties of the polymer brushes were investigated by thermogravimetric analysis and differential scanning calorimetry. After solvent and thermal annealing, the AACPB self-assembles into a hierarchically ordered nanostructure. One is the microphase-separated lamellar nanostructure with a 9.66 nm scale. The other is the cholesteryl double-layer smectic A phase (SmAd) with a 5.46 nm scale. The order–disorder transition of the AACPB is associated with the SmAd–isotropic transition. It is the first report on the microphase separation of AACPBs. We can construct ordered nanostructures with a sub-10 nm length scale with AACPBs. After the doping of 0.2 equiv of LiCF3SO3, the d-spacing of the lamellar structure formed by the PCholMA8-alt-PEO25/LiCF3SO3 complex increases because the interaction between Li+ and oxygen atom makes the PEO chains more stretched. Such a structure offers lithium salt-doped PEO nanochannels which can act as pathways for the transport of lithium ion.
We synthesized a series of rod–rod block copolymers, poly(octyl-4′-(octyloxy)-2-vinylbiphenyl-4-carboxylate)-b-poly(γ-benzyl- l -glutamate) (PVBP-b-PBLG) with different rod diameters, and we ...focused on the effect of size disparity on their self-assembling behaviors in bulk. By using differential scanning calorimetry, wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering, and transmission electron microscopy techniques, we found that the columnar nematic (ΦN) liquid crystalline phase of PVBP and the hexagonal columnar (ΦH) phase of PBLG were disrupted to different extents depending on the volume fractions of PVBP (f PVBP’s). When f PVBP is about 60%, the ΦH phase of PBLG is retained with the appearance of the two second-order diffractions in WAXD patterns. When f PVBP is increased to above 73%, the ordered structure of PBLG is destroyed, and when f PVBP is 91% even the first-order diffraction peak disappears. At the same time, the ΦN phase of PVBP changes from poorly ordered to well ordered with increasing f PVBP. Accordingly, with f PVBP increasing from 60% to 91%, the microphase-separated structure goes through a poorly ordered structure to an interdigitated lamellar morphology and to a bilayer lamellar structure.
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Spinal cord injury is a challenge in orthopedics because it causes irreversible damage to the central nervous system. Therefore, early treatment to prevent lesion expansion is crucial for ...the management of patients with spinal cord injury. Bexarotene, a type of retinoid, exerts therapeutic effects on patients with cutaneous T-cell lymphoma and Parkinson's disease. Bexarotene has been proven to promote autophagy, but it has not been used in the treatment of spinal cord injury. To investigate the effects of bexarotene on spinal cord injury, we established a mouse model of T11-T12 spinal cord contusion and performed daily intraperitoneal injection of bexarotene for 5 consecutive days. We found that bexarotene effectively reduced the deposition of collagen and the number of pathological neurons in the injured spinal cord, increased the number of synapses of nerve cells, reduced oxidative stress, inhibited pyroptosis, promoted the recovery of motor function, and reduced death. Inhibition of autophagy with 3-methyladenine reversed the effects of bexarotene on spinal cord injury. Bexarotene enhanced the nuclear translocation of transcription factor E3, which further activated AMP-activated protein kinase-S-phase kinase-associated protein 2-coactivator-associated arginine methyltransferase 1 and AMP-activated protein kinase-mammalian target of rapamycin signaling pathways. Intravenous injection of transcription factor E3 shRNA or intraperitoneal injection of compound C, an AMP-activated protein kinase blocker, inhibited the effects of bexarotene. These findings suggest that bexarotene regulates nuclear translocation of transcription factor E3 through the AMP-activated protein kinase-S-phase kinase-associated protein 2-coactivator-associated arginine methyltransferase 1 and AMP-activated protein kinase-mammalian target of rapamycin signal pathways, promotes autophagy, decreases reactive oxygen species level, inhibits pyroptosis, and improves motor function after spinal cord injury.
Amphiphilic rod–coil dendritic–linear block copolymers PEG(G m )-b-PMPCS (where m is the number of dendron generation, and m = 1, 2, 3) composed of a semirigid Percec-type dendron with hydrophilic ...poly(ethylene glycol) (PEG) tails and a rod-like mesogen-jacketed liquid crystalline polymer, poly{2,5-bis(4′-methoxy-phenyl)oxycarbonylstyrene} (PMPCS), were successfully prepared. The self-assembled structures undergo a transition from vesicles through large compound vesicles (LCVs) to short cylindrical micelles with increasing dendron generation. PEG(G2)-b-PMPCS forms stable LCVs with porous surfaces of a narrow size distribution in a mixed solvent of tetrahydrofuran and water. The formation mechanism of the supramolecular structure with nano- and microsized scales is studied through changing the rate of water addition. It is composed of two steps: morphological transformation and vesicles fusion or differentiation. Vesicles are precursors for LCVs regardless of what the initial morphology is. However, the final LCV structures are different. Slow addition of water produces spherical LCVs, while those formed during fast water addition are irregular (like deformed spherical) LCVs.
We synthesized a new series of MJLCPs with a polynorbornene main chain, PNbnPT (n = 8, 10, 12, 14, 16, 18, which is the number of carbons in the side-chain alkyl tails), through ring-opening ...metathesis polymerization and investigated their phase behaviors. The monomers were facilely synthesized in satisfactory yields through a key intermediate, N-(2,5-dicarboxylphenyl)-cis-5-norbornene-exo-2,3-dicarboximide. Differential scanning calorimetry, polarized light microscopy, and wide-angle X-ray diffraction results demonstrate that the phase behavior of PNbnPT is strongly dependent on the alkyl-tail length. Polymers with relatively short alkyl tails, PNb8PT and PNb10PT, are amorphous in the whole temperature range before degradation. When the alkyl-tail length increases, PNbnPTs (n = 12, 14, 16, 18) develop into the smectic A phase, and the degree of order increases with increasing alkyl-tail length. The synthetic pathway for MJLCPs with a polynorbornene main chain in this work is more robust and greener than those reported to the best of our knowledge. And MJLCPs with a polynorbornene main chain show quite different phase behaviors compared with those with a polyethylene backbone, and they may be used to create fascinating functional materials.
Tungsten is a commercially important metal element that usually coexists with a variety of non-ferrous metals, which makes its extraction difficult. Scheelite is a commonly occurring ...tungsten-containing ore with the formula CaWO4. Improving the surface properties of scheelite to increase its adsorption of the collector for flotation separation is the focus of our current research. In this paper, the effects of manganese ions on scheelite flotation in benzohydroxamic acid (BHA) system were studied by micro-flotation tests, adsorption tests, fourier transform infrared spectroscopy (FTIR), zeta potential, and X-ray photoelectron spectroscopy (XPS) analysis. The addition of Mn2+ was found to improve the recovery of scheelite. The addition of Mn2+ greatly improved the recovery of scheelite. Infrared spectroscopy, adsorption tests, zeta potential measurements and XPS analysis all confirmed that BHA had a higher adsorption capacity and a stronger bond to the surface of scheelite after the addition of manganese ions, increasing the floatability of scheelite particles. Therefore, Mn2+ shows great potential for the improvement of the flotation index of scheelite in a system with BHA.
Underground gas storage is the best choice for natural gas resource reserve and peak value. Storage capacity of underground gas storage and single well injection and production capacity are the key ...indicators of shaving capacity. This paper focuses on research of expansion of gas storage and the stimulation of injection and production capacity of single well of a basin in Western China. Firstly, based on the study of two-phase seepage law of gas and water, a numerical simulation model coupling high velocity non-Darcy effect and gas-water two phase seepage is established; Secondly, the influencing factors of single well injection and production capacity are analysed. Finally, acidizing can effectively improve the single well injection and production capacity of well. The numerical simulation result shows that the injection and production differential pressure is reduced by 70%, and gas injection and production volume are increased by 14.8% and 26.9%.
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