•Si-CNT composite was synthesized by in situ adding CNT during acid-etching Al-Si alloy powder.•Si nanoparticles were encapsulated in the 3D conducting architecture from CNT and graphene.•The Si-CNT/G paper delivered a capacity of 1100 mAh g−1 after 100 cycles at 200 mA g−1.Silicon/carbon (Si/C) composite shows great potential to replace graphite as lithium-ion battery (LIB) anode owing to its high theoretical capacity. Exploring low-cost scalable approach for synthesizing Si/C composites with excellent electrochemical performance is critical for practical application of Si/C anodes. In this study, we rationally applied a scalable in situ approach to produce Si-carbon nanotube (Si-CNT) composite via acid etching of commercial inexpensive micro-sized Al-Si alloy powder and CNT mixture. In the Si-CNT composite, ∼10 nm Si particles were uniformly deposited on the CNT surface. After combining with graphene sheets, a flexible self-standing Si-CNT/graphene paper was fabricated with three-dimensional (3D) sandwich-like structure. The in situ presence of CNT during acid-etching process shows remarkable two advantages: providing deposition sites for Si atoms to restrain agglomeration of Si nanoparticles after Al removal from Al-Si alloy powder, increasing the cross-layer conductivity of the paper anode to provide excellent conductive contact sites for each Si nanoparticles. When used as binder-free anode for LIBs without any further treatment, in situ addition of CNT especially plays important role to improve the initial electrochemical activity of Si nanoparticles synthesized from low-cost Al-Si alloy powder, thus resulting in about twice higher capacity than Si/G paper anode. The self-standing Si-CNT/graphene paper anode exhibited a high specific capacity of 1100 mAh g−1 even after 100 cycles at 200 mA g−1 current density with a Coulombic efficiency of >99%. It also showed remarkable rate capability improvement compared to Si/G paper without CNT. The present work demonstrates a low-cost scalable in situ approach from commercial micro-sized Al-Si alloy powder for Si-based composites with specific nanostructure. The Si-CNT/graphene paper is a promising anode candidate with high capacity and cycling stability for LIBs, especially for the flexible batteries application.Download high-res image (276KB)Download full-size image

To explore the self-assembling behavior and oil-water interfacial property of the micelle emulsifiers, a kind of coumarin-containing amphiphilic terpolymer, poly (2-(dimethylamino)ethyl methacrylate-co-methyl methacrylate-co-7-(4-vinyl benzyloxyl)-4-methylcoumarin) (PDMV), was prepared. The self-assembly polymeric micelles were used as particulate emulsifiers to stabilize stimuli-responsive emulsions. The micelle size, morphology, self-assembling behavior and photo-cross-linking were investigated with a combination of techniques. The critical water content (CWC) of terpolymers decreased with the increasing hydrophobic segments and initial concentrations. The larger degree of photo-cross-linking the micelles, the lower emulsifying efficiency the micelles. The tertiary amine groups of terpolymers underwent the inversion from protonation to deprotonation with the increasing pH, causing the observed o/w to w/o phase inversion, and there was coverage of spherical nanoparticle on the surface of polymerized styrene beads. Notably, macrophase separation and demulsification were observed under strong alkaline conditions, and some “reef-like” protuberances arose from a smooth surface of solidified polymerized beads. Thus the findings are not only of theoretical interest but also of great practical application in the polymeric surfactants and cosmetics area.Download high-res image (268KB)Download full-size image

We present a novel approach to prepare highly dispersive nano-TiO2 by in situ growth on functional graphene (FG) via impregnation-hydrothermal method. The functional graphene was obtained by means of triethanolamine to modify graphene oxide. The characterization results collected by Fourier-transform infrared spectra, transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy showed that nano-TiO2 particles with anatase phase and a narrow size distribution (the average particle size is 5 nm) were dispersed on the surface of FG uniformly. Then, the photocatalytic activity of as-prepared catalyst under UV light was evaluated, and the results showed that it possessed better photocatalytic activity than pure TiO2 and TiO2 on GO prepared by similar method. In addition, the as-prepared photocatalyst revealed considerable photocatalytic ability under visible light.

•Spiropyran-based random copolymer was synthesized by ATRP.•The negative solvatochromism was observed.•The polarity of comonomer influenced the photochromic behavior of spiropyran.•MAA unit offset the protonation of MC isomer to a large extent.•The random copolymer can be conveniently used to detect Co2+ with high selectivity.An amphiphilic spiropyran-based random copolymer containing methacrylic acid unit has been prepared and investigated with obvious negative solvatochromism in five different solvents. It was found that the polarity of comonomer influenced the photochromic behavior of spiropyran. The synthesized copolymer exhibited a good reversible behavior in aqueous solution: the addition of strong acid promoted the isomerization from spiropyran (SP) to merocyanine (MC), and the inverse process was achieved by the introduction of strong base. Much more importance, the effect of comonomer was utilized for the selective Co2+ recognition. The locations of the maximum absorption peak stay almost as same as MC when it is complexed with Cu2+, Mn2+ and Hg2+. The location, however, moves from 551 nm to 526 nm upon complexation with Co2+. The obvious color change of the solution from purple to claret-red after complexation with Co2+ was observed. This interesting phenomenon is practically convenient for the visual recognition of Co2+.Spiropyran-based random copolymer containing MAA unit can detect Co2+ with high selectivity and sensitivity.

The uniformly dispersed and structured silica nanoparticles were prepared and functionalized by amino and 2-bromoisobutyrate successively. The random copolymer brushes of 2-(dimethylamino) ethyl methacrylate (DMAEMA) and 1′-(2-acryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) were synthesized from 2-bromoisobutyrate-functionalized silica nanoparticles by surface-initiated atom transfer radical polymerization (SI-ATRP). FT-IR, TGA, XPS, TEM, and EDS verified the successful immobilization of initiator and grafting of the random copolymer. Subsequently, the triple responsive behaviors including thermo-, pH- and photo-sensitivities were investigated using dynamic light scattering (DLS) as well as UV-Vis spectrometry. Furthermore, the active palladium was loaded into the hybrid silica nanoparticles and the catalytic performance was evaluated using a styrene hydrogenation reaction at different temperatures.

Poly (methyl methacrylate) (PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization (SI-ATRP). Energy disperse spectroscopy (EDS) and atomic force microscopy (AFM) confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69°. It is found that CuCl/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine (HMTETA) system is more suitable than CuBr/N, N, N′, N″, N″-pentamethyl diethylenetriamine (PMDETA) system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuCl/HMTETA due to higher activity and better reversibility of the former system.

•PDMAEMA brushes were successfully synthesized onto silica particles by SI-ATRP.•For the resulting polymer brushes, much greater ESR is observed at pH 5 than at pH 9.•Adsorption amount of PDMAEMA-g-SiO2 is much higher than that of original silica.•The adsorption process is strongly dependent on the different pH values.Poly(2-(dimethylamino)ethyl methacrylate) brushes on the surface of silica particles were synthesized by surface-initiated atom transfer radical polymerization. The resulting brushes were analyzed and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermo-gravimetric analysis (TGA) and X-ray photoelectron spectrometer (XPS). Equilibrium swelling ratio (ESR) was employed to assess the pH and temperature sensitive behaviors of the resulting PDMAEMA brushes, and much greater ESR was observed at pH 5 than at pH 9. Furthermore, the adsorption behaviors of PDMAEMA brushes for heavy metal ions (Cr(VI)) were investigated, and obvious pH responsive equilibrium adsorption amount was observed.PDMAEMA brushes have been successfully synthesized on the surface of silica particles by surface-initiated atom transfer radical polymerization. Compared to the original silica particles, a much higher equilibrium adsorption amount of heavy metal ions was found for the resulting PDMAEMA-g-SiO2 brushes, and the adsorption process is strongly dependent on different pH values.