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151.
Wannida Apisuk Alexandra G. Trambitas Boonyarach Kitiyanan Matthias Tamm Kotohiro Nomura 《Journal of polymer science. Part A, Polymer chemistry》2013,51(12):2575-2580
Ethylene copolymerizations with norbornene (NBE) using half‐titanocenes containing imidazolin‐2‐iminato ligands, Cp′TiCl2[1,3‐R2(CHN)2C?N] [Cp′ = Cp ( 1 ), tBuC5H4 ( 2 ); R = tBu ( a ), 2,6‐iPr2C6H3 ( b )], have been explored in the presence of methylaluminoxane (MAO) cocatalyst. Complex 1a exhibited remarkable catalytic activity with better NBE incorporation, affording high‐molecular‐weight copolymers with uniform molecular weight distributions, whereas the tert‐BuC5H4 analog ( 2a ) showed low activity, and the resultant polymer prepared by the Cp‐2,6‐diisopropylphenyl analog ( 1b ) possessed broad molecular weight distribution. The microstructure analysis of the poly(ethylene‐co‐NBE)s prepared by 1a suggests the formation of random copolymers including two and three NBE repeating units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2575–2580 相似文献
152.
E. S. Batyeva O. G. Sinyashin V. A. Al'fonsov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):187-190
Abstract The substitution and addition reactions have been studied in the series of thioloderivatives of P(III) acids. The reactions have been shown to proceed with the rupture of the P-S bond, the phosphorus coordination being preserved. 相似文献
153.
Norbornene polymerizations were carried out using nickel(II) bromide complexes CH{C(R)NAr}2NiBr ( 1 , R = CH3, Ar = 2, 6 ? iPr2C6H3; 2 , R = CH3, Ar = 2, 6‐Me2C6H3; 3 , R = CF3, Ar = 2, 6 ? iPr2C6H3; 4 , R = CF3, Ar = 2, 6‐Me2C6H3) in the presence of methylaluminoxane. Compound 3 is the most active norbornene polymerization catalyst of all the nickel complexes tested. The activity of theses catalysts increases with increases in steric bulk of the substituents on the aryl rings. The electronic nature of the ligand backbone also affects the activity. The resulting polynorbornenes are vinyl type by IR and NMR analyses. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
154.
Christer H. Bergstrm Bernd R. Sperlich Juhana Ruotoistenmki Jukka V. Seppl 《Journal of polymer science. Part A, Polymer chemistry》1998,36(10):1633-1638
Norbornene–ethylene copolymers were prepared using the metallocene catalyst ethylene bis (indenyl) zirconium dichloride with MAO, and their microstructure was characterized with 1H-NMR and 13C-NMR methods. From a Cosy 1H-NMR spectrum it was found that all norbornene units are enchained in the exo-configuration. The sequence distribution of norbornene units was investigated using 13C-1H correlations, hmqc for one-bond correlations, and hmbc for two- or three-bond correlations. It was shown that norbornene diads were formed at a high norbornene content (45 mol %). When further increasing the norbornene incorporation (66 mol %) a number of new signals were obtained. A Cosy 1H-NMR spectrum revealed a new crosspeak which, according to the corresponding 13C-NMR shifts (hmqc), correlated well with a terminal unit of a trimer of norbornene. This means that at very high norbornene contents, norbornene triads can be formed. Because the formation of isotactic norbornene triads is very difficult to understand from a sterical point of view, an epimerization process causing stereoirregularities in the norbornene triad is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1633–1638, 1998 相似文献
155.
Frdric Pelascini Frdric Peruch Pierre J. Lutz Marcel Wesolek Jacky Kress 《Macromolecular rapid communications》2003,24(13):768-771
Addition polymerization of norbornene was performed with several pyridine bis(imine) cobalt dichloride complexes activated with methylaluminoxane (MAO), first described for ethylene polymerization. For the first time, norbornene was also polymerized with CoCl2 associated to MAO. The influence of several reaction parameters has been investigated. Quite different behavior was observed compared with ethylene polymerization. Moreover, the copolymerization of ethylene and norbornene with these complexes was not possible but led to a mixture of both homopolymers.
156.
I. Tritto L. Boggioni A. Ravasio C. Zampa J. Hitzbleck J. Okuda S. Bredeau P. Dubois 《Macromolecular Symposia》2007,260(1):114-121
E–N copolymerization with a number of half-sandwich rare-earth metal compounds [M(η5-C5Me4SiMe2R)(η1-CH2SiMe3)2(L)] (M = Sc, Y, Lu) has been achieved. Mainly atactic alternating E N copolymers are obtained with all catalytic systems. Interestingly, copolymers arising from [Sc(η5-C5Me4SiMe2C6F5)(η1-CH2SiMe3)2(THF)]/[/[Ph3C][B(C6F5)4] possess narrower molar mass distributions than those from [Sc(η5-C5Me4SiMe3)(η1-CH2SiMe3)2(THF)] / [Ph3C][B(C6F5)4]. In addition, homogeneous surface coating of multi-walled carbon nanotubes is accomplished for the first time by in situ E–N copolymerization as catalyzed by rac-Et(Ind)2ZrCl2/MMAO-3A anchored onto the carbon nanotube surface. The copolymerization reaction allows for the destructuration of the native nanotube bundles. The relative quantity of E N copolymer can be tuned up as well as the norbornene content in the formed copolymers and accordingly their glass transition temperature. By melt blending with an ethylene-vinyl-co-acetate copolymer (27 wt.-% vinyl acetate comonomer) matrix, high performance polyolefinic nanocomposites are obtained. 相似文献
157.
Mark Lautens Alaa S. Abd-El-Aziz Cathleen M. Crudden 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):569-574
The ring-opening metathesis copolymerizations of deltacyclene, substituted deltacyclene, and norbornene was achieved using RuCl3, ReCl5, and molybdenum alkylidene catalysts. The reaction conditions employed are similar to those used previously in the syntheses of homopolymers. The low conversion copolymerization of deltacyclene and norbornene showed that deltacyclene is more reactive than norbornene by a factor of 2.4. The characterization and physical properties of these copolymers were determined using NMR, GPC, Tg, and viscosity measurements. © 1993 John Wiley & Sons, Inc. 相似文献
158.
Georgios Floros Fotini Agrafioti Alexios Grigoropoulos Patrina Paraskevopoulou Konstantinos Mertis Maria Tseklima Maria Veli Marinos Pitsikalis 《Journal of polymer science. Part A, Polymer chemistry》2013,51(22):4835-4844
Statistical copolymers of norbornene (NBE) with 5‐vinyl‐2‐norbornene (VNBE) were prepared by ring‐opening metathesis polymerization, employing the triply bonded ditungsten complex Na[W2(μ‐Cl)3Cl4(THF)2].(THF)3. NMR measurements revealed that the side vinyl groups of the VNBE monomer remain intact during the copolymerization reaction. The reactivity ratios were estimated using the Finemann–Ross (FR), the inverted FR, and the Kelen–Tüdos graphical methods. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions, which were derived using the monomer reactivity ratios. The glass transition temperatures, Tg, of the copolymers were measured by differential scanning calorimetry measurements and were examined in the frame of several theoretical equations allowing the prediction of these Tg values. The best fit was obtained using methods that take into account the monomer sequence distribution of the copolymers. Finally, the kinetics of the thermal decomposition of the copolymers was studied by thermogravimetric analysis in the frame of the Ozawa–Flynn–Wall and Kissinger methods. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4835–4844 相似文献
159.
A. J. H. Klunder F. J. C. Van Gastel J. M. M. Smits Paul T. Beurskens Gezina Beurskens 《Journal of chemical crystallography》1995,25(7):389-392
The stereogeometry of the title compound which was prepared by a stereoselective addition reaction, has been proved by an X-ray diffraction analysis. Crystal data: monoclinic, P21,a=10.495(16),b=8.392(16),c=13.209(20) Å, =93.80(8),Z=4. The crystal structure has been solved by vector search methods and refined toR=0.05 for 782 observed reflections. 相似文献
160.
Dong‐Po Song Hong‐Liang Mu Xin‐Cui Shi Yan‐Guo Li Yue‐Sheng Li 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):562-570
The facile and efficient functionalization of polynorbornene has been achieved through direct copolymerization of norbornene (NB) with 5‐norbornene‐2‐yl acetate (NBA) or 5‐norbornene‐2‐methanol (NBM) using a series of β‐ketiminato Ni(II)‐Me pyridine complexes 1–4 (Scheme 2 ) in the presence of B(C6F5)3. Remarkably, the monomer conversion could reach up to about 96% in 10 min in the NB/NBA copolymerization. The copolymers with wide NBA contents (3.3–38.4 mol %) were obtained by variation of reaction conditions. These copolymers have high molecular weights (MWs) (Mn = 41.8–144 kg/mol) and narrow MW distributions (Mw/Mn = 1.80–2.27). In the absence of alkyl aluminum compounds, a monomer conversion of 81% was observed in the NB/NBM copolymerization, and copolymers with NBM content in the range of 11.2–21.8 mol % were obtained by variation of reaction conditions. In addition, Ni(II)‐Me pyridine complexes 2 was very active at a low B/Ni molar ratio of 6, while bis‐ligand complex 6 bearing the same ligand just showed moderate efficiency at a high B/Ni molar ratio of 20. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献