Electro-active switchable ultrafiltration membranes are of great interest due to the possibility of external control over permeability, selectivity, anti-fouling and cleaning. Here, we report on hybrid single-walled carbon nanotube (SWCNT)-polyaniline (PANi) nanofibers synthesized by in situ polymerization of aniline in the presence of oxidized SWCNTs. The composite nanofibers exhibit unique morphology of core-shell (SWCNT-PANi) structures with average total diameters of 60 nm with 10 to 30 nm thick PANi coatings. The composite nanofibers are easily dispersed in polar aprotic solvents and cast into asymmetric membranes via a nonsolvent induced phase separation. The hybrid SWCNT-PANi membranes are electrically conductive at neutral pH and exhibit ultrafiltration-like permeability and selectivity when filtering aqueous suspensions of 6 nm diameter bovine serum albumin and 48 nm diameter silica particles. A novel flash welding technique is utilized to tune the morphology, porosity, conductivity, permeability and nanoparticle rejection of the SWCNT-PANi composite ultrafiltration membranes. Upon flash welding, both conductivity and pure water permeability of the membranes improves by nearly a factor of 10, while maintaining silica nanoparticle rejection levels above 90%. Flash welding of SWCNT-PANi composite membranes holds promise for formation of electrochemically tunable membranes.
Coordination assembly and characterization of europium(III) complexes covalently bonded to SBA-15 directly functionalized by modified polymer
The organic ligand sulfosalicylic acid (SSA) which was selected as molecular bridge for sensitization of terbium ions was modified by thionyl chloride (SOCl2) and 3-ammonium propyl triethoxy silane (APTES) to obtain the hybrid precursor SSA-Si. Then the solution of Tb (NO3)3was added in the presence of tetraethylorthosilicate (TEOS). The binary lanthanide organic/inorganic hybrid material was obtained. The ternary hybrid material was obtained by adding the solution of Tb (NO3)3and polyurethane. We investigated the thermal stability and luminescence properties of hybrids and found that the ternary hybrid materials exhibit better thermal stability and stronger emission intensity. Furthermore, compared with the binary mesoporous material Tb-(SSA-Si)3, the ternary mesoporous material Tb-(SSA-Si)3-PU exhibits the characteristic emission of the Tb3+ion with a higher luminescence intensity, suggesting that the introduction of polymer polyurethane into the mesoporous matrix is of benefit for the sensitization of Tb3+luminescence, by replacing H2O groups that can quench the luminescence of Tb3+ion.
Fluorinated polyurethanes (FPU) was prepared using fluorinated polyether polyol (FPO) as the soft segment, 4,4`-diphenylmethane diisocyanate (MDI) as the hard segment, 1,4-butanodiol (BDO) as the chain extender and catalysts. Tin metal catalysts were used to catalyze the polyurethane reaction of polyether polyols and isocyanate. The effect of different catalysts including stannous octoate (T-9) and dibutyltindalautrate (DBTDL) on the structure, surface properties and thermal properties of FPU was studied. The structural elucidation of the synthesized FPU was performed by Fourier transform infrared (FT-IR) and discovered that with decreasing catalyst efficiency or without catalyst, the strength of hydrogen bounds were enhanced. The FPU films surface was characterized by contact angle (CA) and atomic force microscopy (AFM) and it was found that the phase separation was increasing with increasing catalyst efficiency. The thermal property was exhibited by Thermo gravimetric (TG) and showed that joining catalyst improved stability significantly.
Multi-walled carbon nanotubes (MWCNTs) were incorporated into epoxy resin (EP) to improve the resins toughness and thermal properties. MWCNTs/EP composites were prepared by hot melt method. The fracture energy of composites was determined by wedge test, measure length of crack extension of the composites, and calculates the fracture energy. Results show improved composites toughness, as MWCNTs were dispersed in EP matrix evenly, thus absorbed impact energy. Thermal gravimetric analysis (TGA) results suggest that initial decomposition temperature increased by adding MWCNTs, with a promoted formation of a structural antiflaming network, which led to enhancement of thermal stability of the composites. The limiting oxygen index (LOI) and LU-94 data also showed a decrease of flammability of the composites.
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