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Two new routes to polyamides and polyesters were established, based on the polycondensationof new typical active diacylamide of benzotriazole, such as 1, 1'-(isophthaloyl) bisbenzotriazole(IPBBT) and 1, 1'-(terephthaloyl)bisbenzotriazole (PBBT) with diamines, diols and diphenol underdifferent mild conditions. The N-acylation of polycondensation occurred at room temperaturewithout added catalyst, the O-acylation of polycondensation had to complete in the presence oftriethylamine as a catalyst at 60℃. 相似文献
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Facile fabrication of pH-sensitive core-shell nanoparticles based on HEC and PMAA via template polymerization 总被引:1,自引:0,他引:1
Youwei Zhang Qiaorong Jin Jiongxin Zhao Chengxun Wu Qingqing Fan Qimin Wu 《European Polymer Journal》2010,46(7):1425-24
Taking advantage of the specific hydrogen bonding interactions between the components, core-shell nanoparticles based on poly(methacrylic acid) (PMAA) and hydroxyethyl cellulose (HEC) can be efficiently prepared via facile one-step polymerization of MAA on HEC template in water. Various techniques were used to characterize in detail the sizes, morphology, and structures of the nanoparticles, as well as the interactions between the components. The core-shell structures of the nanoparticles were confirmed by TEM observation. Dynamic light scattering and fluorescence spectrometry were used to monitor the polymerization process, which indicates a size decrease and a hydrophobicity increase of the nanoparticles. A mechanism was proposed to explain the formation of core-shell nanoparticles during the template polymerization. The obtained nanoparticles are stable against urea, salt, temperature and in the storage; meanwhile, they exhibit pH-response: the volume of the nanoparticles increased more than six times as pH value of the medium increased from 2.8 to 3.7. 相似文献
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Chengxun Lu Jijin Yang Liecheng Leng Xinde Feng Dechang Li 《Journal of polymer science. Part A, Polymer chemistry》1981,19(12):3333-3343
Preparations of four typical bioactive esters of N-p-methacrylamidobenzoic monomers and their reactive polymers as immobilized trypsin carriers are described. N-p-methacrylamidobenzoic active ester monomers containing ? COONB, ? COOSu, ? COOObt, or ? COOBT group can react with an aliphatic amine such as benzylamine at room temperature to give an identical product, N-benzyl-p-methacrylamidobenzamide. However, only monomers with ? COOObt or ? COOBT group can also react with an aromatic amine such as aniline to give N-phenyl-p-methacrylamidobenzamide. These monmoers polymerized readily in solution with azobisisobutyronitrile as free-radical initiator; the polymers were used to immobilize trypsin. Among the four different active esters for the immobilization of trypsin, thE HONB and HOSu active ester showed rather higher bioactivities than the HOObt or HOBT active ester under the same conditions. Both P(MABONB)-trypsin and P(MABOSu)-trypsin matrices possess higher biological activities by about four or three times that of P(MABOObt)-trypsin or P(MABOBT)-trypsin matrices, respectively. It is proposed that these rather high bioactivities may be attributed to the “specific” aminolysis of reactive polymer with ? COONB or ? COOSu active ester group by aliphatic amino substituents. 相似文献
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We investigate the propagation regimes of laser beam in plasmas with radial distribution of electron temperature, characterized by ratio parameter of radial Gaussian distribution. By following the WKB method and paraxial approximation, the propagation equations of laser beam are derived and discussed for two nonlinearity mechanisms respectively. Both the critical curves for different ratio parameters are plotted, and it is proved that the self-focusing or self-trapping mode could be realized only when the ratio parameter excesses 1. The variations of laser beam-width are calculated, which indicates the feasibly effective modification of propagation characters by radial distribution of electron temperature. 相似文献
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Chen Zhou Jingfeng Yao Lezhi Zhan Chengxun Yuan Anatoly Kudryavtsev Almaz Saifutdinov Ying Wang Zhi Yu Zhongxiang Zhou 《Molecules (Basel, Switzerland)》2022,27(18)
The collisional electron spectroscopy method for analyzing and determining gaseous impurities was further developed to realize the operation in an open environment. In addition, the method not only facilitates the registration of the impurity components, but also the reactive radicals generated from the discharge reaction. The sandwich-like discharge structure was used to generate a stable, non-local, negative glow equipotential plasma in an open environment, and the I–V characteristic curve of the plasma was collected using an additional sensor electrode. The collisional electron spectroscopy was obtained from the first derivative of the probe current I with respect to the probe potential V by adding a diffusion function to correct it. In addition, our experiment verifies the reliability of the sink theory. 相似文献
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Narrowly distributed core‐shell nano‐particles at relatively high concentration (30 mg/mL) were prepared via in situ polymerization of acrylic acid in an aqueous solution of biocompatible gelatin. These polymeric nano‐particles, in aqueous solution, had cores mainly comprised of an insoluble inter‐polymer complex of poly(acrylic acid, PAA) and gelatin and shells comprised of soluble gelatin (denoted as gelatin/PAA nano‐particles). Dynamic light scattering and electrophoretic light scattering techniques were used to trace the in situ polymerization process. The structure of the gelatin/PAA nano‐particle was further locked‐in via shell crosslinking; i.e., the reaction between glutaraldehyde and gelatin. Scanning force microscopy (SFM) was used to observe the morphologies of the particles before and after cross‐linking. Furthermore, the pH responsive behaviors of the gelatin/PAA nano‐particles before and after shell crosslinking were studied. 相似文献
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Chengxun Lu C. G. Overberger 《Journal of polymer science. Part A, Polymer chemistry》1984,22(10):2413-2425
New optically active monomers L -[α-(N-p-acryloxybenzoyl)alanine ethyl esters] (I) and their polymers were synthesized. The title monomers (I) were prepared by the reaction of 1-p-acryloxybenzoyloxy-4-chlorobenzotriazoles (II) with L -alanine ethyl ester hydrochloride, by aminolysis of the active monoester. The new typical active ester (II) was synthesized by the N-hydroxy compound active-ester methods in excellent yield. Before the synthesis of the optically active monomers was carried out, a model study of the aminolysis of the two active esters was performed. 相似文献