Titania-coated polymeric nanoparticles were synthesized based on the cationic colloidal particles which were prepared by surfactant-free emulsion copolymerization of styrene and butylacrylate in the presence of a cationic monomer, methacryloxyethyltrimethyl ammonium chloride (MOTAC) using azobis(isobutylamidine)hydrochloride (AIBA) as an initiator. These cationic particles were stabilized by poly(vinylpyrrolidone) (PVP). Then, these particles were dispersed in ethanol and mixed with titanium(IV) butoxide. Negatively charged titania precursors were rapidly hydrolyzed onto the cationic surfaces of colloidal particles. Subsequently, the samples were heated to 450 degrees C to form anatase TiO2 and to remove the colloidal template, which resulted in hollow nanospheres. The hollow titania particles were characterized with zeta analyzer, transmission electron microscopy, scanning electron microscopy, light scattering, X-ray diffraction, thermogravimetric analysis and FT-IR. 相似文献
Summary: A novel mesoporous organosilica with additional cyclodextrin‐based micropores has been synthesized from tetraethoxysilane (TEOS) and cyclodextrin‐based silane monomer precursors and triblock PEO‐PPO‐PEO (poly(ethylene oxide)‐poly(propylene oxide)‐ poly(ethylene oxide)) copolymer P123 as the structure‐directing template with the aid of sodium chloride and the supramolecular assembly of cyclodextrins with P123.
A new functional glycomonomer was obtained from modified glucosamine. Hemoglobin-imprinted polymer gel was prepared with allyl-bromide modified glucosamine as functional monomer, poly(ethylene-glycol)diacrylate (PEGDA) as cross-linker and ammonium persulfate [(NHn)2S2O8]/sodium hydrogen sulfite (NaHSO3) as initiators in a phosphate buffer. The adsorption capacity and selective adsorption of the molecular imprinting polymer (MIP) were also discussed. 相似文献
Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant (bis-[2-(F-hexyl)ethyl]phosphate sodium), water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N'-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 (w/c) microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2'-azo-bisisobutyronitrile (AIBN), cross-linked poly(acryloxyethyltrimethyl ammonium chloride) particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained. 相似文献
Graphite electrodes coated with chemically-modified polymer films are described. Several different polymers were used, including poly(acrylic acid), poly[triethyl(vinylbenzyl)ammonium chloride], poly[trihexyl(vinylbenzyl)ammonium chloride], and poly[trihexyl(vinylbenzyl)ammonium thiocyanate]. A cation-responsive electrode can be prepared from poly(acrylic acid)-coated graphite. Anion-responsive electrodes can be prepared from graphite coated with polymeric quaternary amines. In these electrodes, the ion-sensing species is irreversibly attached to the polymer (rather than physically entrapped within a polymer matrix); this factor eliminates leaching of the active component, and the addition of a plasticizer is unnecessary. A selective sensor for thiocyanate is described; it yields a Nernstian response over the concentration range 1 × 10?1–1 × 10?5 M sodium thiocyanate. 相似文献
The measurement of local oxygen level in 3D cell culture is desired but remains as a challenge problem. We developed a 3D cell scaffold with luminescence-based oxygen sensing capability that opens the possibility of 3D mapping of oxygen level during cell growth. Hydrogel inverted opal scaffold was prepared by photo-polymerization of poly(2-hydroxyethyl methacrylate (pHEMA) and poly(methacryloyloxy)ethyl-trimethylammonium chloride (pMEATAC) monomer using close-packed bead assembly as template. Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium chloride (Ru(dpp)(3)), was coated on the pHEMA-pMEATAC 3D scaffolds by layer-by-layer (LBL) assembly. pHEMA-pMEATAC copolymer was coated on top of the Ru(dpp)(3) layer as a protection layer. The fluorescence emission of Ru(dpp)(3) can be dynamically quenched by oxygen. By measuring the emission intensity of the scaffold, the local oxygen level can be monitored. The hydrogel scaffolds are transparent, and thus 3D fluorescence intensity can be mapped by confocal microscopy. Human bone marrow stromal cells HS-5 were successfully cultured on the oxygen sensing scaffold, and the observed Ru(dpp)(3) emission intensity from the scaffold was stronger in cell rich area, which indicates a lower oxygen level due to the consumption of the cells. 相似文献
Summary: The ring‐opening polymerization of N‐carboxy anhydrides (NCA) of γ‐benzyl‐L ‐glutamate and β‐benzyl‐L ‐aspartate was studied in the presence of an ammonium chloride‐functionalized poly(ethylene oxide) macroinitiator, which possibly prevents side reactions such as NCA deprotonation. Although polymerization initiated by such macroinitiators was found to be quite slow, well‐defined conjugates of poly(ethylene oxide)‐block‐poly(γ‐benzyl‐L ‐glutamate) and poly(ethylene oxide)‐block‐poly(β‐benzyl‐L ‐aspartate) with polydispersity indexes as low as 1.05 were prepared. Moreover, the presence of ammonium chloride chain ends significantly prevented end‐group cyclization of poly(γ‐benzyl‐L ‐glutamate) after polymerization.
Gel permeation chromatograms recorded for the diblock copolymers of poly(ethylene oxide)‐block‐poly(γ‐benzyl‐L ‐glutamate) prepared by N‐carboxy anhydride polymerization initiated either by PEO‐NH2 macroinitiator or PEO‐NHequation/tex2gif-stack-1.gifCl− macroinitiator. 相似文献
The novel surface imprinted polymer composites (MIP/K(2)Ti(4)O(9)) were prepared using dibenzothiophene (DBT) as the template, 4-vinylpyridine as the functional monomer and potassium tetratitanate whisker (K(2)Ti(4)O(9)) as the carrier. The synthetic product was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Parameters influencing DBT adsorption such as contact time, temperature and DBT initial concentration were investigated. The adsorption kinetics were evaluated with the pseudo-first-order and pseudo-second-order models, and the adsorption isotherms were fitted by Langmuir and Freundlich models. Selectivity experiments showed that MIP/K(2)Ti(4)O(9) exhibited excellent recognition capacity and binding affinity to DBT compared with the comparative substrates. MIP/K(2)Ti(4)O(9) could also be easily regenerated and reused ten times with only about 20% loss of adsorption capacity. 相似文献
The surface contact disinfecting technique is a newly developed method for water sterilization. In this paper, the grafted quaternary ammonium salts (QAS) antibacterial fibers were prepared and designed to apply for the surface contact disinfecting process in water treatment. The antibacterial fibers were directly prepared by grafting methacryloxylethyl benzyl dimethyl ammonium chloride (DMAE-BC) onto cellulose fiber using thiocarbonate-H2O2 redox system. All kinds of factors in the grafting reactions, such as reaction time, reaction temperature, monomer concentration, initiator concentration, which influence the percentage of grafting, were studied and optimized. The modified cellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope(SEM). The effects of the percentage of grafting of the grafted cellulose fibers on bactericidal activity were also studied. The spread plate method was used to characterize the bactericidal activity. The disinfection process was further investigated by directly observing the morphology of the bacterial cells adsorbed on the antibacterial fibers with SEM and measuring extracelluar total protein concentration in suspension. The poly(DMAE-BC)-grafted cellulose ?ber was found to exhibit particularly high activity against E.coli. 相似文献
Calcium oxalate (CaOx) particles with different morphologies and phase structures were prepared by a facile precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly(sodium 4-styrene-sulfonate) (PSSS) at different temperatures. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The influence of experimental conditions including pH, temperature, and concentration of PSSS and CaC2O4 on the morphologies and phase structures of the prepared calcium oxalate particles were investigated. It was found that variations in the concentration of PSSS and CaC2O4, temperature, and pH significantly influenced the crystal structure, morphology, and particle size of the samples. Various crystal morphologies of calcium oxalate, such as plate, leaf-shaped, bipyramid, and cylinder could be fabricated, depending on the experimental conditions. Higher PSSS concentration and reaction temperature favored the formation of metastable calcium oxalate dihydrate (COD) crystals and stable calcium oxalate monohydrate (COM), respectively. Especially, cylinder-shaped CaC2O4 particles were obtained at 80 degrees C in the presence of PSSS for the first time. This research may provide new insight into understanding and potentially regulating the formation of kidney stones and the control of morphology and phase structures of calcium oxalate particles. 相似文献
Layer‐by‐layer (LbL) assembly technique is applied for the first time for the preparation of nitrogen‐doped carbon capsules. This approach uses colloid silica as template and two polymeric deposition components, that is, poly(ammonium acrylate) and a poly (ionic liquid) poly(3‐cyanomethyl‐1‐vinylimidazolium bromide), which acts as both the carbon precursor and nitrogen source. Nitrogen‐doped carbon capsules are prepared successfully by polymer wrapping, subsequent carbonization and template removal. The as‐synthesized carbon capsules contain ≈7 wt% of nitrogen and have a structured specific surface area of 423 m2 g−1. Their application as supercapacitor has been briefly introduced. This work proves that LbL assembly methodology is available for preparing carbon structures of complex morphology. 相似文献
A template approach to the synthesis of a series of conjugated polymer-mesoporous silica composite microspheres is described. Poly(3,4-ethylenedioxythiophene) (PEDOT), poly(thiophene), and poly( N-methylpyrrole) composites were prepared. The surface morphology of the samples was analyzed by scanning electron microscopy, and it was found that well-defined, monodisperse colloidal materials could only be prepared when the monomer is insoluble in the polymerization medium. The filling of the mesopores was systematically varied from 0% to 100%, and powder X-ray diffraction and nitrogen adsorption studies were used to confirm the pore filling. Thermogravimetric analysis shows that the polymer loading tracks the monomer loading in an asymptotic fashion. Conductivity measurements show that the conductivity of the PEDOT materials is relatively constant at high polymer loadings but decreases exponentially at low loadings. Measurements of the electrophoretic mobility were made in order to explain this behavior. These data suggest that, at high polymer loadings, the particle surface is characteristic of the polymer, while at low polymer loadings it is characteristic of the silica host. These results identify important design criteria for the template synthesis of a variety of new colloidal materials. Importantly, these optimized parameters may open the door to the preparation of colloids and colloidal crystals of previously unprocessable materials. 相似文献