Polymerizations of butadiene,isoprene, and 2,3-dimethylbutadiene by Gd(OCOCCl3)3–(i-Bu)3Al–Et2AlCl and the cis polymerization mechanism for dienes

Homopolymerizations of butadiene (BD), isoprene (IP), and 2,3-dimethylbutadiene (DMBD) were carried out by a Gd(OCOCCl₃)₃-based catalyst, to investigate the effects of the energy levels of the monomers or the sterical factor of the methyl substituents on the polymerizability and the cis-selectivity of the monomers. The order of the polymerizability at 50°C was as follows: BD (4.5 kg of polymer/(mol of Gd h)) ∼ IP (4.8) > DMBD (0.6). On the other hand, the cis-selectivity of the polymers was as follows: BD (98%) > IP (94%) > DMBD (35%). These results suggest that the terminal BD and IP units are controlled by the cis configuration by the coordination between the penultimate cis-vinylene unit and the catalyst metal, whereas the penultimate DMBD unit unfavorably controls the terminal DMBD unit to the cis-1,4 configuration through the back-biting coordination with difficulty by two methyl substituents compared with the penultimate BD and IP units. The validity of the back-biting coordination was examined by MO calculation with σ-allylnickel complexes. According to the formation energy with respect to the BD–BD diad, the cis–cis form is somewhat preferable to the trans–cis form through the coordination of the penultimate BD unit by ΔE = 0.028 au (ca. 17.6 kcal/mol). © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2283–2290, 1998     

Ethylene/Norbornene Copolymerization with iPr(Cp)(Flu)ZrCl2 Catalyst: Effect of MAO Cocatalyst and 3rd Monomer

The copolymerization of ethylene and norbornene (N) was carried out with iPr(Cp)(Flu)ZrCl₂ catalyst and modified methylaluminoxane (MMAO) cocatalyst. The catalytic activity was dependent on the structure of MMAO, i.e., MMAO-4 exhibited higher catalyst activity than MMAO-3A containing more i-butyl groups. The glass transition temperature (T_g) and the composition of the produced copolymer were not affected by MMAO type. With styrene derivatives as 3^rd monomer, T_g of copolymer increased while the catalytic activity decreased. With the addition of 3^rd monomer, not only the content of 3^rd monomer but also the content of N increased.     

Synthesis,Antimicrobial Activity and Semi-conducting Properties of Novel 2-(4-Chloro-1-Naphtyloxy)-2-Oxoethyl Methacrylate with 2-(Diethylamino)Ethyl Methacrylate Copolymers

The free-radical initiated copolymerization of 2-(4-chloro-1-naphtyloxy)-2-oxoethyl methacrylate (ClNOEMA) with 2-(diethylamino) ethyl methacrylate (DEAEMA) was carried out in 1,4-dioxane solution at 70 ± 1°C using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios (ranging from 0.15 to 0.85) in the feed. The copolymer composition obtained by elemental analysis led to the determination of reactivity ratios employing Fineman-Ross (F-R) and Kelen-Tüdös (KT) linearization methods. These parameters were also estimated using a non-linear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The prepared homo and copolymers were tested for their antimicrobial activity against bacteria and yeast. These copolymers have been converted into novel salts by reaction with the iodemethane (CH₃I). The copolymers and the corresponding salts have been characterized fully by a range of spectroscopic analysis techniques. The electrical conductivity dependence of temperature of the polymers were measured and the polymers exhibit the semi-conducting behavior, confirming that the electrical conductivity increases with increasing temperature. The poly(CINOEMA-co-DEAEMA) polymer doped by CH₃I for 15 min shows the highest conductivity. The optical band gap, activation energy and room temperature conductivity values of these polymers were obtained. These electronic parameters suggest that the poly(CINOEMA-co-DEAEMA)s doped by CH₃I for 15 min is an organic semiconductor with the thermally activated conduction mechanism.     

Reverse atom transfer radical polymerization of vinyl monomers with Fe[SC(S)NEt2]3 alone as the catalyst

The living radical polymerization of methyl methacrylate and styrene was successfully carried out with diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS)/ferric tri(diethyldithiocarbamate) as a novel reverse atom transfer radical polymerization initiation system in which DCDPS was a hexa‐substituted ethane‐type thermal iniferter, DC was a diethyldithiocarbamate group, and no additional ligands such as nitrogen‐ or phosphine‐based compounds were required. The bulk polymerization of methyl methacrylate was carried out at 95 °C, and that of styrene was carried out at 120 °C. Poly(methyl methacrylate) and polystyrene (PSt) with high molecular weights and quite narrow molecular weight distributions (as low as 1.09 for PSt) were obtained. ¹H NMR spectroscopy revealed the presence of an α‐(carbethoxycyanophenyl)methyl group from the initiator and an ω‐DC group from the catalyst in the obtained polymers. Various chain‐extension reactions under UV light or thermal treatments were successfully conducted to prove the presence and efficient reinitiating of the ω‐DC group. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3464–3473, 2001     

2-甲基-2-丁烯二酸单甲酯的合成及其与丙烯腈二元共聚的表观竞聚率的测定

以柠糠酸酐为原料, 合成了一种可以与丙烯腈(AN, acrylonitrile)共聚的新单体: 2-甲基-2-丁烯二酸单甲酯(MBAME). 以偶氮二异丁腈(AIBN, 2,2’-azobis isobutyronitrile)为引发剂, 70 ℃下引发MBAME与AN在N,N-二甲基甲酰胺(DMF, N,N-dimethylformamide)中进行无规共聚, 通过Fineman-Ross法测定了两者在DMF溶液聚合体系的表观竞聚率, γ1(AN)＝7.985, γ2(MBAME)＝0.599, 有助于优化聚丙烯腈基碳纤维用树脂的生产工艺.     

Property modification of poly(methyl methacrylate) through copolymerization with fluorinated aryl methacrylate monomers

Copolymers of methyl methacrylate (MMA) with 2,3,5,6‐tetrafluorophenyl methacrylate (TFPMA), pentafluorophenyl methacrylate (PFPMA), and 4‐trifluoromethyl‐2,3,5,6‐tetrafluorophenyl methacrylate (TFMPMA) were investigated. All the three systems showed a random copolymerization character. The composition, glass transition temperature (T_g), and refractive index of the copolymers obtained were studied. T_gs of TFPMA/MMA and PFPMA/MMA copolymers were found to deviate positively from the Gordon–Taylor equation. However, T_gs of TFMPMA/MMA copolymers were well fit with the Gordon–Taylor equation. These results indicated the existence of interaction between MMA and either TFPMA or PFPMA units in copolymers. This interaction resulted in the enhancement of the T_g of MMA polymers through the copolymerization with TFPMA and PFPMA. The refractive index and the light transmittance of copolymers were close to those of PMMA. Copyright © 2007 John Wiley & Sons, Ltd.     

异丁烯与对氯甲基苯乙烯正离子共聚合研究

以四氯化钛(TiCl4)、二氯乙基铝(AlEtCl2)、倍半铝(AlEt1.5Cl1.5)、三氯化铝(AlCl3)等路易斯酸为共引发剂,水或枯基醇(CumOH)为引发剂,在-80℃下的正己烷/二氯甲烷(V/V=6/4)的混合溶剂内,研究了异丁烯(IB)与对氯甲基苯乙烯(p-CMS)的正离子共聚合.利用示差凝胶渗透色谱仪(GPCRI)以及核磁氢谱(1H-NMR)对共聚物的表观分子量及分子量分布、共聚组成等进行分析,采用KelenTüd?s与Yezreielv-Brokhina-Roskin法计算了单体竞聚率,初步探讨了p-CMS与IB正离子共聚合的反应机理.结果表明,AlEtCl2、AlEt1.5Cl1.5、AlCl3均可催化大分子间的烷基化反应,产生凝胶;TiCl4作为共引发剂,可以得到无凝胶单峰分布共聚物;邻位氯甲基苯乙烯(o-CMS)不能参与共聚,p-CMS的共聚活性较低,IB与p-CMS的单体竞聚率为rIB=4.67,rp-CMS=0.70;随反应时间延长,共聚物中p-CMS的含量及共聚物分子量均逐渐增加;p-CMS单体自身几乎不参与引发,共聚到大分子链后,苄基氯缓慢参与引发,形成支化.提高共聚合温度至-60和-40℃,聚合速率降低,p-CMS的引发活性未发生明显变化.     

新型茂钛催化剂用于St/Bd嵌段共聚物的合成

先用五甲基茂基三苄氧基钛 /甲基铝氧烷催化苯乙烯预聚 ,再与丁二烯进行嵌段共聚合。考察预聚时间、催化剂浓度、苯乙烯浓度等条件对嵌段共聚合反应的影响。共聚产物经沸丁酮、沸甲苯、沸四氢呋喃、沸氯仿连续抽提后 ,嵌段共聚物主要存在于氯仿的可溶级分中。随着预聚时间的增加 ,共聚反应催化效率增加 ,共聚产物中丁二烯含量下降 ;随着催化剂浓度增加 ,共聚催化效率增加 ,[Ti]为 2 .0× 1 0 -4 mol/L时 ,共聚活性达到最大值 ( 1 7.78× 1 0 3 gP/gTi) ,随着催化剂浓度进一步增加 ,共聚催化效率下降 ,共聚产物中丁二烯含量变化亦存在峰值。     

Copolymerization of styrene and butadiene with Ni(acac)2-methylaluminoxane catalyst

Copolymerization of styrene (St) and butadiene (Bd) with nickel(II) acetylacetonate [Ni(acac)₂]-methylaluminoxane (MAO) catalyst was investigated. Among the metal acetylacetonates [Mt(acac)_x] examined, Ni(acac)₂ showed a high activity for the copolymerization of St and Bd giving copolymers having high cis-1,4-microstructure in Bd units in the copolymer. The effect of alkylaluminum as a cocatalyst on the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst was observed, and MAO was found to be the most effective cocatalyst for the copolymerization. The monomer reactivity ratios for the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst were determined to be r_St = 0.07 and r_Bd = 3.6. Based on the obtained results, it was presumed that the random copolymers with high cis-1,4-microstructure in Bd units could be synthesized with the Ni(acac)₂-MAO catalyst without formation of each homopolymer. The polymerization mechanism with the Ni(acac)₂-MAO catalyst was also discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3838–3844, 1999     

Preparation of Organic/Inorganic Hybrid Materials Using Agregates of Poly{2-methyl-N-[2-(phenylthio)phenyl] Acrylamide-co-2-(Trimethylsyloxy)Ethyl Methacrylate} as Precursor and Vibrational Investigation of the Polymerization

Acrylamide based monomer, 2-methyl-N-[2-(phenylthio)phenyl]acrylamide (MPPA) was synthesized by reacting 2-(phenylthio) aniline with methacryloylchloride. The copolymerization of MPPA, with 2-(trimethylsyloxy)ethyl methacrylate(TSEM) was carried out with different monomer-to-monomer ratios in the feed. All the compounds were characterized by IR, Raman and ¹H- and ¹³C-NMR techniques and SEM analysis. The elemental analysis of the copolymer composition led to the determination of reactivity ratios employing Fineman-Ross, Kelen-Tüdös and Extended Kelen-Tüdös linearization methods. These parameters were also estimated using a non-linear computational fitting procedure, known as reactivity ratio errors in variable model. The molecular weights and polydispersity index of polymers was determined by gel permeation chromatography. Thermal stability of the copolymers were found to increase with increasing mole fraction of MPPA from thermogravimetric analysis. The vibrational analysis of MPPA and poly(MPPA) were also performed to explain the vibrational spectra and to confirm the polymerization on the basis of a theoretical and experimental aproach.     

Low- and high-conversion studies of the free radical copolymerization of 2-hydroxyethyl methacrylate with styrene in N,N′-dimethylformamide solution

2-Hydroxyethyl methacrylate (HEMA) and styrene (S) have been copolymerized in a 3 mol · L⁻¹N,N′-dimethylformamide (DMF) solution using 2,2′azobis (isobutyronitrile) (AIBN) as an initiator over a wide composition and conversion range. From low-conversion experiments and ¹H-NMR analysis, the monomer reactivity ratios were determined according to the Mayo–Lewis terminal model. The comparison of the obtained results with those previously reported for copolymerization in bulk and in toluene reveals a relatively small but noticeable solvent effect that can be qualitatively explained by the bootstrap model. Cumulative copolymer composition as a function of conversion is satisfactorily described by the integrated Mayo–Lewis equation; overall copolymerization rate increases with increasing the HEMA/S ratio, and individual monomer conversion is closely related to the monomer molar fraction in the feed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2941–2948, 1999     

Growth and Spectroscopic Properties of Nd3＋：Sr3Gd2（BO3）4 Crystal

<正>This paper reports the growth,X-ray diffraction and spectroscopy of Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal.A Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal with dimensions ofφ20×45 mm~3 has been grown by the Czochralski method.Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal belongs to the orthorhombic system,space group Pnma(D_(2h))with a=0.7401,b=1.604 and c=0.8755 nm.The absorption and emission spectra of Nd~(3+):Sr_3Gd_2(BO_3)_4 were investigated.The absorption cross sectionσ_a is 3.11×10~(-20)cm~2 at 808 nm. The absorption transition at 808 nm has an FWHM of 14 nm.The luminescence lifetimeτ_f is 51.7 us.The emission cross sectionσ_e at 1064 nm wavelength is 1.09×10~(-19)cm~2.     

Copolymerization of a dendronized monomer with styrene and different acrylates: Determination of reactivity ratios

The reactivity ratios for the copolymerization of a first‐generation dendronized monomer with styrene and different acrylates are determined. The obtained ratios as well as the copolymer compositions that can be expected are discussed in detail. The influence of the dendron on the polymerization potential of the monomer is estimated by comparing its reactivity to those of linear systems as well as using higher generations of the dendronized monomer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Copolymers of (±)2-ethylhexyl acrylate and 3-[3,3,3-trimethyl-1,1-bis (trimethylsiloxy) disiloxanyl] propyl methacrylate

Statistical copolymers of (±)2-ethylhexyl acrylate and 3-[3,3,3-trimethyl- 1,1-bis (trimethylsiloxy) disiloxanyl] propyl methacrylate were synthesized and the reactivity ratios and the Q and e values were calculated. The glass transition temperatures of the copolymers were in good agreement with the predictions of Fox's equation and Wood's formula. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3571–3574, 1997     

Pd-catalyzed synthesis of 3-(diarylmethylene)-2-oxindoles and 3-(arylmethylene)-2-oxindoles

An efficient method for the stereoselective synthesis of 3-(diarylmethylene)-2-oxindoles and 3-(arylmethylene)-2-oxindoles via carbopalladation is described. In this approach, an Ugi-4-component reaction (4-CR) adduct was used as the starting material. A one-pot sequence involving intermolecular carbopalladation C-H activation/C-C bond formation efficiently afforded the oxindole derivatives.     

Studies of ethylene–styrene copolymerization with dinuclear constrained geometry complexes with methyl substitution at the five‐membered ring in indenyl of [Ti(η5:η1‐C9H5SiMe2NCMe3)]2 [CH2]n

The new dinuclear half‐sandwich CGC (constrained geometry catalyst) with methyl substitution in indenyl, [Ti(η⁵:η¹‐2‐methylindenyl)SiMe₂NCMe₃]₂ [(CH₂)_n] [n = 6 ( 10 ), n = 9 ( 11 ), n = 12 ( 12 )], have been synthesized, and structure of these complexes has been characterized by ¹H and ¹³C NMR. The most important feature is that two protons of methylene directly bonded to the indenyl ring become inequivalent to be shown as two separated resonances at 2.9 and 3.0 ppm, probably due to the formation of planar chirality caused by a titanium complex formation. It has been found that the dinuclear CGCs with methyl substitution at an indenyl ring were very active catalysts for ethylene and styrene copolymerization. The activity increases in the order of 10 < 11 < 12 , which indicates that the presence of a longer bridge between two active sites contributes to facilitate the polymerization activity of the dinuclear CGC more effectively. This result might be understood by the implication that the steric factor rather than the electronic factor may play a major role to direct the polymerization behavior of the dinuclear CGC. It is found that the dinuclear catalysts are very efficient to incorporate styrene in the polyethylene backbone. The styrene contents in the formed copolymers ranged from 5 to 40% according to the polymerization conditions. One can observe strong signals at 29.7 ppm of the polyethylene sequences, and, in addition, peaks at 27.5, 36.9, and 46. 2ppm (S_βδ, S_αδ, and T_δδ, respectively) of sequences of EESEE. Weak peak at 25.3 ppm are attributed to S_ββ, which represents SES sequence. The absence of a signal for T_ββ at 41.3 ppm and for S_αα at 43.6 ppm shows there is no styrene–styrene sequences in copolymers. This result indicates that the dinuclear CGC are very effective to generate well‐distributed poly(ethylene‐co‐styrene)s. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1712–1723, 2004     

石墨炉原子吸收光谱中GdCl3,Gd（NO3）3基体的背景吸收

研究了石墨炉原子吸收光谱中ＧｄＣｌ３、Ｇｄ（ＮＯ３）３基体的背影吸收影响。背景吸收波长特性的研究表明，ＧｄＣｌ３和Ｇｄ（ＮＯ３）３的背景吸收都具有明显的波长特性。蒸发行为研究表明ＧｄＣｌ３的背景吸收主要来自ＧｄＣｌ３的分子蒸气，Ｇｄ（ＮＯ３）３的背景吸收主要来自ＮＯ。钆基体的背景吸收峰高与灰化有关，ＧｄＣｌ３背上曲线轮廓与原子化温度和原子化方式有关。Ｇｄ（ＮＯ３）３的背景吸收远小于ＧｄＣｌ３。本文     

Copolymerization with depropagation: A study of α‐methyl styrene/methyl methacrylate in bulk at elevated temperatures

Previously published material on the α‐methyl styrene/methyl methacrylate (α‐MS/MMA) copolymer system at temperatures above the ceiling temperature of α‐MS has focused on low‐conversion results. Several attempts have been made to estimate copolymer reactivity ratios from experimental data, but in most cases errors are present in the determination of copolymer composition variables. In this article, the results of rigorous parameter estimations, as applied to two sets of equations developed independently by P. Wittmer (Adv Chem 1971, 99, 140–174) and H. Kruger, J. Bauer, and J. Rubner (Makromol Chem 1987, 188, 2163–2175), are discussed. Experimental data for the copolymer system at low conversions, as well as over the full conversion range, are presented, covering a temperature range of 60–140 °C. A comparison of the data trends with traditional copolymer systems indicates that the reversibility of both MMA and α‐MS must be considered when composition, polymerization rate, or molecular weight equations are being developed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1981–1990, 2000