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Copolymers of pentafluorophenylhexafluoroisopropyl methacrylate (FPPMA) with trifluoroethyl methacrylate (TFEMA) were prepared in THF solution and in bulk using azobisisobutyronitrile as a free radical initiator. The monomer reactivity ratios of TFEMA (M1) and FPPMA (M2) were calculated as r1 = 0.55 and r2 = 0.07. The refractive indices of poly(TFEMA) and poly(FPPMA) are very similar as 1.435 and 1.430, respectively, at 532 nm, and the copolymer films were transparent. The glass transition temperatures (Tg) of the copolymers were in the range of 80–90°C and showed a negative deviation from the Gordon–Taylor equation. The thermal decomposition temperature (Td) was increased with the content of FPPMA in copolymers. Low water absorption for 1:1 FPPMA/TFEMA copolymer was detected. Copolymers of FPPMA with hexafluoroisopropyl methacrylate (HFPMA) were also prepared. The monomer reactivity ratios of HFPMA (M1) and FPPMA (M2) were calculated as r1 = 0.43 and r2 = 0.10. The Tgs of the copolymers were in the range of 88–95°C and showed also a negative deviation from the Gordon–Taylor equation. Tg and Td of the copolymers were increased with the content of FPPMA. The refractive index of poly(HFPMA) (1.384 at 532 nm) is much lower than that of FPPMA homopolymer, but copolymer films obtained were clear and transparent. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Abstract Blends of poly(pyridinium ethyl methacrylate perchloride) and poly[oligo(oxyethylene) methacrylate-co-acrylamide] were prepared, and the ionic conductivity and mobility of the blends were investigated. Results indicate that both the transference of perchlorate anion and the dissociation of the polymeric salt in the comblike polyether obey the thermoactivation mechanism, and that the perchlorate anion in the blends is free. 相似文献
215.
Characterization of Nitro-Substituted Polybenzimidazole Synthesized by the Reaction with Nitric Acid
Abstract Nitro-substituted poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole]s (PBIs) were synthesized by the reaction of PBI with nitric acid in sulfuric acid under various conditions. The number of nitro groups substituted on the aromatic ring of PBI per polymeric unit varied from 1.44 to 3.55 according to the reaction conditions. An increase in reaction temperature and concentration of the nitric acid increased the degree of substitution. The inherent viscosity of the substituted polymer increased as the reaction temperature decreased. When the reaction temperature was 30°C, the inherent viscosity of the polymer increased as the concentration of nitric acid increased. The nitro-substituted PBI exhibited polyelectrolyte behavior in formic acid. The nitro groups substituted on PBI were dissociated when the polymer was heated to 450°C, displaying exothermic behavior, and the decomposition of polymer was proportional to its nitro group content. All nitro-substituted PBIs showed better solubilities in polar aprotic and acidic solvents, such as dimethylacetamide, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, formic acid, sulfuric acid, and trifluoromethanesulfonic acid. 相似文献
216.
Hongming Chen Zhenghua Deng Yungui Zheng Wu Xu Guoxiang Wan 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1273-1281
Abstract The ion conduction of a blend of poly(oxyethylene) (PEO) and lithium methoxy oligo(oxyethylene) sulfate (SAL8) and its electrochemical characteristics were studied. The maximum ambient conductivity of the blend reaches 1.2 × 10?6 S/cm. The blend exhibits single-ion conduction, excellent mechanical performance, and electrochemical stability. A battery of Li/PEO + SAL8/Li1+xV3O8 has a constant discharge capacity at different discharge current densities up to a certain voltage, while the discharge capacity of Li/P (MEO16-AM) + LiClO4/Li1+xV3O8 decreases with an increase of the discharge current density. 相似文献
217.
Hongmei Yang Zong‐Jun Li Debin Wan Wenhui Lian Shuying Liu 《Journal of mass spectrometry : JMS》2013,48(5):539-543
In this work, laser‐enhanced in‐source decay (LEISD) technique of matrix‐assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI‐FT‐ICR‐MS) was used to distinguish reducing and nonreducing carbohydrates. Interestingly, easier cleavage of (1 → 2)‐linked glycosidic bonds for nonreducing carbohydrates containing D‐fructofuranosyl units was observed in MALDI‐FT‐ICR‐MS, which was in agreement with the result of theoretical calculation by the software package Gaussian 09. Importantly, no cross‐ring cleavage of fructofuranosyl residues was detected in the LEISD spectra of nonreducing carbohydrates. LEISD method therefore offers an attractive alternative for fast and efficient differentiation of reducing and nonreducing carbohydrates, and the positions of nonreducing monosaccharide residues in a carbohydrate chain could be easily speculated. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
218.
Jintao Wan Cheng Li Zhi-Yang Bu Hong Fan Bo-Geng Li 《Journal of Thermal Analysis and Calorimetry》2013,114(1):365-375
A four-directional benzene-centered aliphatic polyamine, MXBDP, with high functionality and low volatility, is used to cure epoxy resin (DGEBA). Herein we originally report the isothermal cure kinetics and dynamic mechanical properties of DGEBA/MXBDP. Differential scanning calorimetry confirms that MXDBP is more reactive than commercial linear metaxylenediamine and branched Jeffamine T-403 and the isothermal curing reaction is autocatalytic. The Kamal model is found to be able to well describe the curing rate up to the onset of diffusion control, and the excellent match over the whole conversion range is achieved using the extended Kamal model. Interestingly, the isoconversional kinetic analysis indicates that the effective reaction activation energy (E α ) changes substantially with conversion, and ultimately decreases to a very small value (<10 kJ mol?1) because of the diffusion-controlled reaction kinetics. Then, dynamic mechanical analysis reveals that DGEBA/MXBDP exhibits the higher α- and β-relaxation temperatures and the much higher crosslink density than DGEBA/metaxylenediamine. Our experiment results support that MXBDP has the high reactivity and improved thermal resistance in combination with the advantages of the high functionality, low volatility and decreased CO2 absorption. Therefore, MXBDP may be especially suitable for room temperature-cure epoxy coatings and adhesives. 相似文献
219.
石墨烯基铁氧化物磁性材料的制备及在水处理中的吸附性能 总被引:1,自引:0,他引:1
石墨烯及其衍生物氧化石墨烯均有良好的物理和化学性质,其巨大的表面积和丰富的官能团使其成为良好的吸附材料。石墨烯基磁性材料则综合了石墨烯的吸附能力和磁性材料易分离的特性,是水处理过程中具有巨大应用潜力的吸附材料。本文在论述了石墨烯、氧化石墨烯及铁氧化物磁性材料对水体中的重金属离子、有机染料及含苯环的芳香类污染物的吸附富集性能的基础上,重点介绍了石墨烯基铁氧化物磁性材料的不同合成方法及复合材料在水处理中去除污染物的能力,探讨了复合材料在水处理中的应用前景。 相似文献
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