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51.
52.
Yuan Yuan WANG Hui SUN Juan LI Dong JIANG Li Yi DAI 《中国化学快报》2006,17(1):117-120
Room temperature ionic liquids (RTILs) as advanced, technological solvents can be designed to fit a particular application. They used as green “media and/or catalysts” for chemical synthesis have been extensively reviewed recently. RTILs1 not only show … 相似文献
53.
甲基丙烯酸缩水甘油酯/苯乙烯固相接枝聚丙烯 总被引:6,自引:0,他引:6
以苯乙烯(St)为共单体,过氧化苯甲酰(BPO)为引发剂,采用固相接枝反应将甲基丙烯酸缩水甘油酯(GMA)接枝到聚丙烯(PP)大分子链上。研究了反应时间、单体用量、引发剂用量等因素对接枝率的影响。采用凝胶渗透色谱(GPE)测定了PP和接枝物PP-g-(GMA-St)的分子量和分子量分布。结果 表明固相接枝PP反应条件为[GMA/[St]=2,反应3.5h,加入GMA 10份,BPO 5份。St的加入有助于GMA与PP的接枝,同时在一定程度上抑制了PP的降解。 相似文献
54.
The thermal degradation characteristics of head-to-head poly(styrene) [HHPS] should provide insight with respect to the impact
of head-to-head placement on the thermal stability of traditional atactic head-to-tail polymer [HTPS]. The synthesis of head-to-head
poly(styrene) must be accomplished indirectly. The head-to-head polymer is most satisfactorily obtained by dissolving metal
reduction of poly(2,3-diphenyl-1,3-butadiene) [PDBD] generated by radical polymerization of the corresponding diene monomer.
Full saturation of the polymer mainchain requires several iterations of the reduction procedure. Since the decomposition of
poly(2,3-diphenyl-1,3-butadiene) is prominent at 374°C and that for head-to-head poly(styrene) is similarly facile at 406°C,
it seemed feasible that TG of partially hydrogenated PDBD might be utilized as a convenient means of monitoring the extent
of hydrogenation. This has been demonstrated for various levels of unsaturation remaining - from approximately 90 to less
than 10%. Within this range the peak areas from the DTG plots of the partially hydrogenated polymer provide a good reflection
of the ratio of unsaturated to saturated units in the polymer. Even low levels of unsaturation in the polymer may be detected
by the asymmetry of the decomposition peak for the polymer.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
55.
L. Yu. Dolgikh I. L. Stolyarchuk P. E. Strizhak A. V. Shvets V. G. Il’in 《Theoretical and Experimental Chemistry》2006,42(1):37-42
The dependence of the activity and selectivity of ion-exchanged forms of zeolite X with incorporated cesium process in alkylation
of toluene with methanol in the side chain on the nature of the ion-exchanged cations (Na+, Cs+, Mg2+, Zn2+) has been established. It is shown that introduction of Mg2+ and Zn2+ in combination with Cs2CO3 significantly increased the yields of ethylbenzene and styrene in comparison with their yields on alkali forms of zeolite
X.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 33–38, January–February, 2006. 相似文献
56.
An operationally simple oxidative methyl esterification of primary alcohols in good yields using an iodine‐mediated poly[4‐(diacetoxyiodo)styrene] in methanol at room temperature is described. The polymeric reagent can be regenerated and reused as an environmentally benign reagent. 相似文献
57.
聚苯乙烯磺酸掺杂聚苯胺的合成 总被引:7,自引:1,他引:7
以苯胺(An)为单体,过硫酸铵(APS)为氧化剂,在聚苯乙烯磺酸(PSSA)的水溶液中,合成了可完全溶于水的PSSA掺杂PAn。研究了An浓度,PSSA浓度,APS浓度,APS的滴加时间,反应时间及温度对An聚合反应及其产物的水溶性,导电性及特性粘度[η]的影响。结果表明:在比较宽的实验条件下,都可以合成出具有良好导电性的可溶于水的PSSA掺杂PAn;其中当An:PSSA:APS的摩尔比为1.7:2.5:1,APS溶液的滴加时间为3h,反应时间为1h,反应温度为14℃时,得到的掺杂PAn导电率最高达0.156S/cm。 相似文献
58.
Poly{2, 5- bis [ (p- methoxyphenyl ) oxycarbonyl] styrene } was successfully syn-thesized. This new polymer has a structure characteristic of mesogen-jacketed liquidcyrstalline polymers (MJLCPs) and does form a liquid crystal phase above its glass tran-sition. It thus became the starting member of a new series of MJLCPs. The synthesis ofthe polymer as well as the liquid crystalline properties of the polymer and its monomerwas discussed. A brief comparison of the new monomer and polymer with some previouslyreported counterparts was also included. 相似文献
59.
Shokyoku Kanaoka Nobuyuki Ikeda Akira Tanaka Hitoshi Yamaoka Toshinobu Higashimura 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2449-2457
Random copolymers with high molecular weights of indene and p‐methylstyrene (pMeSt) were synthesized by cationic polymerization with trichloroacetic acid/tin tetrachloride in CH2Cl2 at low temperatures. When indene and pMeSt (1:1 v/v), for example, were polymerized at ?40 °C, both monomers were consumed at very similar rates to give a copolymer with high molecular weight [number‐average molecular weight (Mn): 8–9 × 104]. This is indeed quite unexpected behavior for the combination of these two monomers because pMeSt polymerized over 1000 times faster than indene in the homopolymerization under the reaction conditions previously described. The product copolymer of indene and pMeSt had a random monomer sequence in it that was confirmed by NMR analyses and thermal‐property measurements. In sharp contrast with pMeSt, styrene and p‐chlorostyrene, which have no electron‐donating groups on the phenyl ring, led to low molecular weight polymers (Mn < 10,000) in the copolymerization with indene (1:1 v/v). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2449–2457, 2002 相似文献
60.
Judit E. Puskas Sam W. P. Chan Kimberley B. McAuley Sohel Shaikh Gabor Kaszas 《Journal of polymer science. Part A, Polymer chemistry》2005,43(22):5394-5413
This article is a critical analysis of kinetic dataavailable on carbocationic polymerizations. A survey of published propagation rate constant (kp) data revealed several orders of magnitude differences. In this article, an explanation of this apparent discrepancy is offered with a case study involving the carbocationic polymerization of 2,4,6‐trimethylstyrene (TMS). With the polymerization mechanism originally proposed for this system, kp = 1.35 × 104 L mol?1 s?1 was extracted from experimental data with the Predici polyreaction package. The alternative mechanism yielded kp = 1.01 × 107 L mol?1 s?1, close to that predicted by Mayr's Linear Free Energy Relationship (LFER). We propose that true rate constants can only be obtained from direct competition experiments or from kinetic interpretation based on independently proven mechanisms. The second part of this review discusses critical analysis of the temperature and concentration dependence of various living IB systems. Comparison of the temperature dependence in systems initiated with 2‐ chloro‐2,4, 4‐ trimethylpentane (TMPCl)/TiCl4 from various laboratories yielded of ΔH ~?25 and ?34.5 kJ/mol for high and low TMPCl/TiCl4 ratios, respectively. Aromatic (cumyl‐type) initiators show ΔH ~ ?40 kJ/mol, whereas H2O/TiCl4 in the presence of the strong electron‐ pair donor dimethylacetamide gave ΔH = ?12 kJ/mol. The significant differences indicate different underlying mechanisms with complex elementary reactions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5394–5413, 2005 相似文献