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71.
72.
丙烯酸酯和甲基丙烯酸酯基团转移共聚研究 总被引:1,自引:0,他引:1
研究了三种丙烯酸酯分别和四种甲基丙烯酸酯的基团转移共聚,用1H NMR法测定共聚物组成,扩展的Kelen Tudos法测定竞聚率,结果为γMA=923、γMMA=006;γEA=1415、γMMA=001;γBA=751、γMMA=002;γMA=1441、γEMA=001;γMA=1396、γBMA=023;γMA=866、γi BMA=008,表明基团转移聚合同阴离子聚合有明显的相似之处. 相似文献
73.
Eiichi Kobayashi Shojiro Kaita Sadahito Aoshima Junji Furukawa 《Journal of polymer science. Part A, Polymer chemistry》1995,33(13):2175-2182
Homo- and copolymerizations of butadiene (BD) and styrene (St) were carried out by gadolinium catalysts having various tricarboxylate ligands [Gd(OCOR)3: R = CH3, CH2Cl, CHCl2, CCl3, and CF3], to investigate the effects of ligands and discuss the cis polymerization mechanism. Polymerization of BD with Gd(OCOR)3—(i—Bu)3Al—Et2AlCl catalysts was carried out in hexane at 50°C. By each catalyst, poly(BD) having a high cis content (cis = 97–99%) in 22–85% yields for 2–24 h were obtained. The ligands with low pKa values increased the polymerization activity as follows: R of Gd(OCOR)3: CF3 > CCl3 > CHCl2 > CH2Cl ~ CH3. On the other hand, in the polymerization of St or copolymerization of BD and St under similar conditions, the highest activity was attained by a Gd(OCOCCI3)3- based catalyst. The difference in the optimum ligand among the homo- and copolymerization of BD and St was discussed on the basis of energy levels of the catalysts. In the copolymers of BD and St, the cis-1,4 content of the BD unit decreased with increasing St content. Furthermore, according to the diad analysis of copolymers (St content ~ 14.5 mol %) by 13C NMR spectroscopy, the low cis value of the BD unit was observed in the St-BD diad (cis/trans/vinyl = 24/53/23), while the high cis value of the BD unit remained in the BD-BD diad (cis/trans/vinyl = 89/10/1). These results suggest that the terminal BD unit is controlled by the cis configuration by the coordination between the penultimate cis vinylene unit and the gadolinium metal catalyst, whereas the presence of the penultimate St unit interferes with cis polymerization of the terminal BD unit. The difference in the coordination mechanism in the course of polymerization between rare earth metal and transition metal catalysts such as the Ni(acac)2 and Co(acac)3-based catalyst was also discussed. © 1995 John Wiley & Sons, Inc. 相似文献
74.
新型螺环单体的合成和自由基聚合反应的研究王宏鲁剑涛冯品珍(中国科学技术大学研究生院化学部北京100039)关键词自由基聚合,新单体合成,螺环单体,自由基共聚虽然离子型开环聚合早已为人熟知,但是自由基开环聚合反应的研究和应用开发还刚刚起步.... 相似文献
75.
Mingzhu Liu Rongshi Cheng Jingjia Wu Cheng Ma 《Journal of polymer science. Part A, Polymer chemistry》1993,31(13):3181-3186
A study was made of the ceric ammonium nitrate (CAN) initiated graft copolymerization of methyl acrylate (MA) onto potato starch. The variables affecting the graft were investigated. The optimums have been obtained; they are the concentrations of MA, CAN, and nitric acid (HNO3) (1.08, 5.0 × 10?3, and 0.081 mol/L, respectively). The reaction temperature is ca. 50°C and the reaction time is 2 h. The molecular weight of grafted poly(methylacrylate) has been determined. On the basis of experimental results, the mechanism of grafting has been explored, a new kinetic equation of the graft copolymerization is established: Rp = Kkd [STOH] [Ce4+] + Kkpkd/kt[STOH][M], where K, kd, kp, and kt are constants. The equation fits the results of experiments. © 1993 John Wiley & Sons, Inc. 相似文献
76.
等离子体辐照的聚乙烯表面接枝交联共聚合 总被引:1,自引:1,他引:1
聚合物利用低温等离子体预辐照进行表面接枝共聚合已有报道.此方法的优点是接枝层被限制在聚合物表面,辐照过程对基材本体性质无影响,且整个过程对环境无污染. 用等离子体使聚合物表面产生自由基,不需要表面具有不饱和键或特殊官能团,因而适用于任何聚合物,甚至于一些无机物如玻璃等.利用等离子辐照后暴露于空气的聚合物表面上生成的过氧自由基或过氧化物进行接枝反应,一般接枝量不大.本工作中,我们自己设计了反应器,以超高分子量聚乙烯(UHMWPE)为基材,以甲基丙烯酸甲酯(MMA)为接枝单体,在无氧条件下利用等离子体辐照产生的表面自由基进行了接枝聚合,产物接枝量高达10%.还用顺磁共振技术对表面自由基性质及其在接枝过程中的行为进行了跟踪研究. 相似文献
77.
78.
Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2002,40(10):1504-1518
The synthesis of new water‐soluble photoinitiators (PIs) based on hydroxyalkylphenones, benzophenones, and thioxanthones with carbohydrate residues such as glucose, cellobiose, and 1‐amino‐1‐deoxy‐D ‐glucitol (glucamine) is described. In addition, selected initiators were reacted with methacryloyl chloride to obtain copolymerizable initiators with improved migration stability. Results from photo differential scanning calorimetry and gel‐content measurements in commercially available water‐thinnable and emulsion‐type resins as well as 2‐hydroxyethyl acrylate are included. Glucose‐modified PIs gave the best results with respect to compatibility with the resin, reactivity, and gel content. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1504–1518, 2002 相似文献
79.
This paper is concerned with the synthesis of poly (ether-urethane) with pendant amino groups. The copolyether produced by ring opening copolymerization of tetrahydrofuran and epibromohydrin was treated with sodium azide in dimethylformamide to form azido substituted copolyether. The poly (ether-urethane) made from it was subjected to reduction reaction to convert azido group to amino group. The stress-strain behavior and dynamic-mechanical properties of poly (ether-urethane) containing pendant amino groups were studied. 相似文献
80.