Pb(Zr0.53Ti0.47)O3 (PZT) films of 10 to 50 m in thickness were prepared by a new sol-gel process using an interfacial polymerization technique. The interfacial polymerization process is that an alkoxide precursor solution is poured on the surface of water in a container to form a gel film at the interface between the two immiscible liquids. The precursor solution was prepared by adding PZT alkoxide solution, PZT powders coated with Pb5Ge3O11 (PG), and a surfactant into hexane solvent. After the polymerization at the interface, the gel films were gently placed on a silicon substrate by draining the water in the container. The gel films containing PZT powders were sintered at 950°C for 10 min to obtain crystallized PZT films. The remanent polarization of a PZT thick film was 33.1 C/cm2. The piezoelectric d33 constant measured with a Mach-Zehnder interferometer was 225 pm/V and was independent of frequency from 0.2 to 3 kHz. 相似文献
The formation of a PZT film of 10–20 m in thickness via an interfacial polymerization of metal-organic precursors has been studied. A commercially available PZT precursor solution developed for dip- or spin-coating was diluted with hexane containing acetylacetone as chelating agent. The solution was poured on water contained in a teflon reaction container of 88 mm inside diameter. A translucent gel film was formed at the interface of the two immiscible liquids. While floating on water it shrank as the evaporation of solvent proceeded until its diameter decreased to about 45% of its initial value. The dried gel film was almost pore free and its thickness was estimated to be about 10 m. 相似文献
The monodisperse, poly(glycidylmethacrylate-co-ethylenedimethacrylate) beads with macroporous in the range of 8.0-12.0 microm were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. The pore size distribution of the beads was evaluated by gel permeation chromatography and mercury instrusion method. Based on this media, a hydrophobic interaction chromatographic (HIC) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages for biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery and good resolution for proteins. The dynamic protein loading capacity of the synthesized HIC packings was 40.0 mg/ml. Six proteins were fast separated in less than 8.0 min using the synthesized HIC stationary phase. The HIC resin was firstly used for the purification and simultaneous renaturation of recombinant human interferon-gamma (rhIFN-gamma) in the extract solution containing 7.0 mol/l guanidine hydrochloride with only one step. The purity and specific bioactivity of the purified of rhIFN-gamma was found more than 95% and 1.3 x 10(8) IU/mg, respectively. 相似文献
Summary: A novel method, situ polymerization stringed assembly (SPSA), is proposed to prepare stable solid or hollow supramolecular polymer particles, which are assembled by numerous nanoparticles. By this method, the fabrication of primary nanoparticles (poly(methyl methacrylate), PMMA), the linkers (polyvinylpyrrolidone, PVP, chains) between the nanoparticles, and the final assembled solid or hollow particles could be achieved in just one‐pot by methyl methacrylate (MMA)/N‐vinylpyrrolidone (NVP) microemulsion polymerization under UV irradiation. The structures of the supramolecular particles can be changed from solid to hollow by tuning the mass ratio of MMA/NVP in the microemulsion. AFM, TEM, and SEM experiments are performed to identify the results.
AFM image of the PMMA/PVP solid particles obtained from the photopolymerization of the microemulsion containing 20 wt.‐% MMA, 10 wt.‐% NVP, and 5 × 10−2 wt.‐% BP. 相似文献
It has been established that the combination of microchannel (MC) emulsification and UV-induced gelation is quite effective in producing mono-sized gel particles from acryloyl-type monomer/polymer solutions. MC emulsification allows one to produce the monomer solution droplets with less than ca. 5% relative standard deviation. On the other hand, using UV-induced gelation technique, pre-gel droplets containing a photoinitiator gelate by irradiation of UV light for a few minutes without requiring heating and/or intermediate adding of reaction accelerator. Conveniently, the particle size is adjusted from a few m to ca. 100-m by changing the slit size of the MC plate. Furthermore, gel particles may contain a variety of materials, such as metals, pigments, dyes, oils, bubbles, or others, suggesting various potential industrial applications. 相似文献
Investigation into the mussel‐inspired polymerization of dopamine has led to the realization that other compounds possessing potential quinone structures could undergo similar self‐polymerizations in mild buffered aqueous conditions. To this end, 5‐hydroxyindazole was added to a dopamine polymerization matrix in varying amounts, to study its incorporation into a polydopamine coating of silica particles. Solid‐state 13C NMR spectroscopy confirmed the presence of the indazole in the polymer shell when coated onto silica gel. SEM and DLS analysis also confirmed that the presence of the indazole in the reaction matrix yielded monodisperse polymer‐coated particles, which retained their polymer shell upon HF etching, except when high levels of the indazole were used. Characterization data and examination of incorporation mechanism suggests that the 5‐hydroxyindazole performs the function of a chain‐terminating agent. Cytotoxicity studies of the polymer particles containing 5‐hydroxyindazole showed dramatically lower toxicity levels compared to polydopamine alone.
It was found that 276 nm-sized styrene-butyl acrylate-methacrylic acid terpolymer (P(S-BA-MAA)) (50.4/40.9/8.7, molar ratio) particles produced by emulsifier-free emulsion polymerization dissolved in a polyoxyethylene nonylphenylether nonionic emulsifier aqueous solution at pH values above 11 and above 25°C resulted in polymer microemulsion. The weight-average diameter of P(S-BA-MAA) microparticles in the solution was 31 nm, which was measured by dynamic light scattering spectroscopy. Such a dissolution of the particles was not observed in the absence of the emulsifier.Part CXLI of the series Studies on Suspension and Emulsion. 相似文献
Size-exclusion chromatography (gel filtration chromatography or gel permeation chromatography) in conjunction with online synchrotron radiation solution small-angle X-ray scattering optics, absorbance, and/or refractive index detectors was further assessed by application of biological macromolecules, such as the hollow sphere protein complex, apoferritin, and a linear polysaccharide, pullulan. The net X-ray scattering patterns of the eluted 24-mer molecule of apoferritin showed the specific character for the hollow spherical shape. The chromatographic (time-resolved) X-ray scattering data of the linear polysaccharide pullulan revealed the flexible chain structure during the chromatographic separation in an aqueous solution. These further applications demonstrated that the present measurement technique will be useful for not only the determination of the radius of gyration value of less than about 10?nm and molecular weight below several hundred thousand but also for the structural characterization of the various macromolecules during the chromatography.
Figure
Typical time-resolved scattering patterns and chromatograms in the SEC-SAXS measurement system 相似文献
Radiation-induced emulsion polymerization of ethylene with ammonium perfluoro-octanoate as an emulsifier was studied in order to elucidate the effect of the number of polymer particles. Owing to the stable structure of the emulsifier from a radical attack, no C? F bond was detected in the polyethylene as expected. The polyethylene produced was mostly gel containing a small amount of low molecular weight polyethylene. This may be attributable to chain transfer to the polyethylene. The effects of dose rate and of concentration of the emulsifier were determined without considering the chain-transfer reaction to the emulsifier. By considering the escape of the radical which is produced by chain transfer to the monomer from the polymer particle to the aqueous phase at the steady state, the following equation is derived: The experimental results could be explained by this equation, and the apparent rate constants were obtained. 相似文献
A sequential polydepsipeptide containing a tripeptide sequence L-alanyl-Lalanyl-ethyl L-glutamyl and an-hydroxy acid L-lactic acid, poly(Ala-Ala-Glu(OEt)-Lac), was synthesized to prepare the microspherical particles by the solvent evaporation process. In this case, the solvents play the most important role for the preparation of polydepsipeptide microspheres and, as an example, when 200 mg of the polydepsipeptide dissolved in 10 ml of 98/2% chloroform/dichloroacetic acid mixture was stirred at 400 rpm and 30 C, the microspherical particles with mean diameter of 58m were formed after pouring into 200 ml of 1% (w/v) poly(vinyl alcohol) solution. 17-Estradiol was incorporated into the particles, and the resulting particles were found to contain 5 mg of drug per 25 mg of the particle. The in vivo release of drug from the microspherical formulation was evaluated by measuring the pharmacological influence on rat prostate. It was found that the sufficient amount of drug, keeping the effective pharmacological influence, is supplied during the first 12-week period, followed by an incomplete supplying of drug intil the implant is perfectly degraded in vivo in the 25th week from the start of implantation. 相似文献
Herein, we report on the synthesis of film-forming poly(styrene-co-butyl acrylate-co-acrylic acid)/SiO2 [P(St-BA-AA)/SiO2] nanocomposites by in situ formation of SiO2 nanoparticles from TEOS via sol–gel process in the presence of poly(acrylic acid) (PAA)-functionalized poly(styrene-co-butyl acrylate) [P(St-BA)] particles fabricated by soap-free emulsion polymerization. The formed silica particles could be absorbed by polyacrylate chains on the surface of PAA-functionalized P(St-BA) particles; thus, raspberry-like polymer/silica nanocomposites would be obtained. Transmission electron microscopy, Fourier transform infrared spectroscopy, attenuated total reflectance infrared spectrum, ultraviolet–visible transmittance spectra, and thermogravimetric analysis were used to characterize the resulting composites. The results showed that the hybrid polymer/silica had a raspberry-like structure with silica nanoparticles anchored on the surface of polymer microspheres. The thermal, fire retardant, and mechanical properties and water resistance of the film were improved by incorporating silica nanoparticles, while the optical transmittance was seldom affected due to nanosized silica particles uniformly dispersed in the film.
Figure
Film-forming polymer/silica nanocomposites with raspberry-like morphology have been successfully prepared via soap-free emulsion polymerization followed by the sol–gel process. The number and the size of SiO2 particles coated on the surface of polymer particles can be adjusted by the amounts of TEOS and ammonia. After the film formation of polymer/silica nanocomposites, silica nanoparticles are homogeneously dispersed within the film without aggregation. 相似文献
Three types of aromatic polyamide particles have been prepared from reacting diamines and diacid chlorides in an acetone or dioxane solution that includes water, using the precipitation polymerization method employing ultrasonic irradiation. The particle diameters were in the range from 300 nm to 1.2 µm with a narrow size distribution. The surface morphology and crystallinity differed greatly among the particles. They began to degrade at temperatures above 400 °C. Also the morphology depended on the ultrasonic frequency. The addition of water was essential to form particles using this polymerization method. Further it was useful to increase the molecular weights of polyamide products.
The alkaline synthesis of porous phenol-formaldehyde polymers containing iminodiacetic acid is described. Porosity is induced by the addition of a finely divided solid material (template) that is insoluble under the reaction conditions. This template is removed by dissolution after the polymerization is complete. Silica gel, carbonate salts and various other salts are used as templates. Resins containing different phenols are synthesized and their effectiveness for the removal of radioactive cesium and strontium from alkaline concentrated sodium salt brines is examined. This matrix typifies the composition of soluble defense nuclear waste.This paper was prepared in connection with work done under Contract No. DE-AC09-76SR00001 with the U.S. Department of Energy. 相似文献
Alkali-soluble copolymer (butyl acrylate/acrylic acid) was synthesized via solution polymerization and used as the emulsifier to prepare acrylic resin for leather finishing agent. The influence of the synthetic conditions, such as the contents of acrylic acid and the initiator types on the properties of P(BA/AA) was investigated in detail. Fourier Transform Infrared Spectrometer (FTIR) indicated that the polymerization reaction of P(BA/AA) was complete without “CC” absorption peak. Differential Scanning Calorimeters (DSC) analysis confirmed that the glass transition temperature (Tg) of P(BA/AA) was −44 °C, Transmission Electron microscope (TEM) indicated that the copolymer latex particles dispersed evenly and were less than 100 nm. Moreover, in contrast to acrylic resin prepared with sodium dodecylsulfate (SDS) and alkylphenol ethoxylates (OP-10) as the emulsifiers, the applied properties of light leather finished by acrylic resin in use of P(BA/AA) as the emulsifier were measured: The air permeability increased by 18.5% as well as the water-resistance by 28.08% and the wet rub fastness by half class, respectively. 相似文献
The preparation of nanosized, molecularly imprinted polymer particles by nonaqueous emulsion polymerization is presented. Monodisperse cross‐linked polymer nanospheres with a diameter of around 100 nm were synthesized using a standard monomer mixture of methacrylic acid and ethylene dimethacrylate, containing (±)‐propranolol as a template. The rebinding efficiency of the resulting particles was determined by batch rebinding tests and isothermal titration calorimetry (ITC). The results indicate that the proposed imprinting process under nonaqueous conditions lead to particles with an enhanced capacity of template rebinding compared to both nonimprinted ones and to particles obtained by more conventional emulsion polymerization in water.