No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Synthesis of poly(N,N′-methylenebisacrylamide-co-4-vinylpyridine) microgels by γ-Ray irradiation
Abstract
γ-Ray irradiation was successfully used in the surfactant-free emulsion copolymerization of N,N′-methylenebisacrylamide(Bis) and 4-vinylpyridine(4-VP), leading to a series of microgels with average hydrodynamic radius(Rp) ranging from 56 nm to 152 nm. However, when acrylic acid (AA), methacrylic acid (MAA) or acrylamide(AM) were used instead of 4-VP, unstable white emulsions or white bulk gels were obtained. The poly (N,N′-methylenebisacrylamide-co-4-vinylpyridine) (poly( Bis-co-4-VP) ) microgels were characterized by infrared spectroscopy, differential scanning calorimetry and transmission electron microscopy. The effects of the ratio of monomers, absorbed dose and dose rate on the synthesis of poly(Bis-cos-4-VP) microgels were studied through Rh, absorbance and gel ratio. The results showed that the size of microgels could be controlled either by the absorbed dose or by the ratio of monomers. The mechanism concerning the formation of microgels was also discussed.
... In previous work, 4-vinylpyridine, with a feasible coordination with metal ions [48,49], as well as its easy formation of microgel [50], was applied to the preparation of a hybrid microgel through the simultaneous formation of Ag NPs and poly(4-vinylpyridine) microgel by γ irradiation and surfactant free emulsion polymerization in a single step [51,52]. It was found that the Ag NPs were well dispersed within the polymer microspheres [51,52]. ...
... In previous work, 4-vinylpyridine, with a feasible coordination with metal ions [48,49], as well as its easy formation of microgel [50], was applied to the preparation of a hybrid microgel through the simultaneous formation of Ag NPs and poly(4-vinylpyridine) microgel by γ irradiation and surfactant free emulsion polymerization in a single step [51,52]. It was found that the Ag NPs were well dispersed within the polymer microspheres [51,52]. ...
Nanosilver/poly(acetoacetoxyethyl methacrylate–styrene) (nano-Ag/P(AAEM-St)) composites were synthesized via emulsifier-free emulsion with silver nitrate solution, AAEM, and St monomer copolymerization by ultrasonic. The morphology and structure of the composites were characterized by ultraviolet and visible spectroscopy, X-ray diffractometer, and transmission electron microscopy, respectively. The results show that Ag nanoparticles with face-centered cubic structure are homogeneously dispersed in the P(AAEM-St) matrix. The thermal stability and the thermal degradation kinetics of P(AAEM-St) were investigated using the thermogravimetric analysis and Kissinger and Flynn–Wall–Ozawa method, respectively. The results prove that the thermal stability of the pure P(AAEM-St) is better than that of the nano-Ag/P(AAEM-St) composites.
Silver-poly(4-vinylpyridine) (Ag-P4VP) hybrid microgels were synthesized by γ-irradiation and surfactant-free emulsion polymerization in a single step. The effects of dose rate and the concentrations of isopropanol, silver-ion, N, N′-methylenebisacrylamide (Bis) and 4-vinylpyridine (4-VP) on the hybrid microgels were studied in detail via transmission electron microscopy (TEM), powder X-ray diffraction (XRD) or dynamic light scattering (DLS). The results indicated that the size of Ag nanoparticles in the hybrid microgels increased with the increase of Ag+ or Bis concentration and with the decrease of dose rate or isopropanol concentration. When the dose rate was decreased, the phase state of Ag nanoparticles was gradually transformed from amorphous state to cubic crystalline state. Although the variety of the P4VP microgels' size was more complex, it could also be easily adjusted by the above-mentioned conditions.
The copolymer PHG based on alpha,beta-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) functionalized with glycidyl methacrylate has been exposed in aqueous solution to a gamma-ray source at different irradiation doses (2, 2.5 and 3.5kGy), alone or in combination with poly(ethylene glycol)dimethacrylate (PEGDMA) or poly(ethylene glycol)diacrylate (PEGDA). The irradiation produces microgel systems that have been characterized by viscosity measurements. Lyophilization of microgels gives rise to samples able to swell instantaneously in water whereas their treatment with acetone produces swellable microparticles that have been characterized.
From the temperature dependence of the extent of binding of small molecules by macromolecules, one finds that binding is mostly exothermic. But very rare endothermic processes have been reported. The endothermic phenomenon was never discussed in terms of the crosslinked hole size of macromolecules. In this paper the extents of binding of methyl orange by 4-vinylpyridine-N,N prime -methylenebisacrylamide copolymers with various degrees of crosslinking have been examined, and their temperature dependence is discussed in terms of the crosslinked hole size. The evidence presented in this paper supports the suggestion that the crosslinked hole size dependence on the temperature variation can be a cause of the bell-shaped phenomenon in the binding of methyl orange by crosslinked poly(4-vinylpyridine). 9 Refs.
The paper reviews recent results of radiation crosslinking of poly(vinyl methyl ether) (PVME). It will give an overview of possible characterization methods for both, soluble and crosslinked PVME. The irradiation of aqueous low concentrated PVME solutions with γ-rays of low doses results in structural changes of PVME molecules. We are able to monitor changes in the chemical structure by spectroscopic methods (IR, NMR) as well as the changes of molecular parameters (e.g. molecular weight, molecular weight distribution, branches) by classical methods for polymer characterization (size exclusion chromatography with diverse detector systems, SLS, viscosimetry). The characterization of the network parameters (crosslinking density νc, molecular weight of the network chains Mc) of PVME bulkgels crosslinked by irradiation at high dose values by classical methods (swelling and compression measurements) provides incorrect results because of the high porosity of the gels. PVME microgel particles can be prepared by irradiation of a phase separated diluted aqueous PVME solution above their lower critical solution temperature. These microgels with decreased dimensions were characterized by SLS, DLS and field emission scanning electron microscopy.
A resin containing 3-(dimethylamine)propyl acrylate and 4-vinylpyridine was synthesized by radical polymerization (in 1:1 mole ratio). Ammonium persulfate (0.5 mol %) and N,N′-methylene-bis-acrylamide (2 mol %) were used as initiator and crosslinking reagents, respectively. The resin was characterized by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The ability to bind Hg(II), Cd(II), Zn(II), Pb(II), Cu(II), and Cr(III) as well as the maximum adsorption capacity and elution of Hg(II) ions from the loaded resin was studied. Sorption selectivity from ternary mixture Hg(II), Cd(II), and Zn(II) was studied at the optimum sorption pH value. At pH 2 the adsorbent retained 98% of Hg(II); the retention of the other metal ions was lower than 20%. The elution assay was made in HClO4 solutions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2559–2563, 2002