间甲基苯酚钾为调节剂的丁二烯负离子聚合反应

在正丁基锂(n-BuLi)／间甲基苯酚钾(m—ROK)／二乙二醇二甲醚／丁二烯／二甲苯的负离子聚合体系中,研究了m—ROK用量对链转移反应、聚丁二烯相对分子质量及微观结构的影响。结果表明。当m—ROK／n—BuLi(摩尔比)小于0．5时,聚丁二烯的特性黏数和相对分子质量迅速下降,链转移次数增加;当m—ROK／n—BuLi(摩尔比)大于0．5时,则不遵循此变化规律。m—ROK的加入明显加宽了聚丁二烯的相对分子质量分布。增加m—ROK用量时,聚丁二烯的微观结构中1,2-结构质量分数下降,顺式-1,4-结构和反式-1,4-结构质量分数增加。     

水溶性单体分散聚合的研究进展

综述了丙烯酰胺等六类水溶性单体分散聚合的研究现状。     

Radical polymerization of itaconic anhydride and reactions of the resulting polymers with amines and alcohols

Itaconic anhydride was polymerized in the presence of a radical initiator under various conditions. The bulk polymerization at 75°C yielded polymer with molecular weight of more than 20000. The reactions of the resulting polymer with water and alcohols gave poly(itaconic acid) and its esters, respectively. The polymers prepared by such reactions were found to have similar thermal properties to those prepared by homopolymerizations of the respective itaconic acid derivatives. Poly(N-substituted itaconomic acid)s, which are difficult to obtain by direct polymerization of their monomers, were prepared by the reactions of poly(itacononic anhydride) with amines. Copolymerizations of itaconic anhydride with electron-donating monomers, styrene and isobutyl vinyl ether, gave alternating copolymers which were then converted by esterification to the respective copolymers of dialkyl itaconates with such electron-donating monomers.     

Molecular engineering of organic reagents and catalysts using soluble polymers

The separation of the final product of a reaction from byproducts, catalysts, or excess reagents is a process common to all synthetic procedures. Various methods to facilitate such separations continue to receive increasing attention as avenues to refine synthetic protocols. This review discusses recent developments in one of these areas, the use of soluble polymers as supports for organic synthesis and catalysis. The general purpose of such work is to combine the principal beneficial features of heterogeneous and homogeneous systems to achieve facile product/catalyst recovery without the polymer affecting the chemistry of known solution-phase processes. The work described here demonstrates that it is often possible to engineer a desired solubility profile, phase behavior, reactivity/selectivity profile, and other beneficial properties into a synthetic reagent or catalyst system by an appropriate choice of soluble polymer support and recovery scheme. In this review, emphasis is given to research published within the last two years.     

Polyether based side-chain liquid crystalline polymers: Anionic polymerization and phase structures

Side-chain liquid crystalline (SCLC) polyethers with different spacers are successfully synthesized via anionic polymerization for the first time. The molecular weights of the polymers can range up to ∼53 kg/mol with M_w/M_n <1.1. The precise chemical structures including end groups have been characterized by employing Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) and the polymerization condition free of side reactions is further discussed. The phase behavior and structures of the polyethers have been investigated by combining various techniques including differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS) and polarized light microscopy (PLM). Two phase transformations are generally observed for each type of SCLC polyethers. Based on 2-dimensional (2D) X-ray patterns of oriented fiber and mechanically sheared samples, the low ordered liquid crystalline phase at high temperature is identified as a SmA phase for both SCLC polyethers. It is found that the polyether with a longer spacer exhibits a complex phase which is a mixture of a HexB phase and a frustrated HexB phase in analogy to smectic antiphase, whereas no such effect occurs for the polymer with a shorter spacer. Only HexB phase is observed for the low temperature phase of this polymer. The difference in phase structures is also revealed in the texture changes of PLM.     

Reactivity in radical polymerization ofN-substituted maleimides and thermal stability of the resulting polymers

Summary The effect ofN-substituents on the radical polymerization ofN-substituted maleimides (RMI) was investigated. The polymerization reactivities, i.e. yield and molecular weight of the polymers, were found to change depending on the structure of theN-substituents. The poly(RMI)s bearing a bulkyN-substituent were confirmed to be semiflexible poly(substituted methylene)s which were soluble in many organic solvents, but did not melt below their decomposition temperatures. From thermogravimetric analysis determined in a nitrogen stream, no weight-loss of poly(RMI) was observed at temperature below 300°C, and the maximum decomposition temperature was 400–440°C, except forN-tert-alkyl substituted derivatives which decomposed at 240–280°C via a two-step reaction.     

Polymerization of butadiene and copolymerization of butadiene with styrene using neodymium amide catalysts

The polymerization of butadiene was performed with catalysts based on the complex Nd{N(SiMe₃)₂}₃ (1). This amide complex in combination with methyaluminoxane or with a boron compound ([HNMe₂Ph][B(C₆F₅)₄], [CPh₃][B(C₆F₅)₄] or B(C₆F₅)₃) and Al(iBu)₃ showed high activity and stereospecificity in polymerization of butadiene. The cationic complex [Nd{N(SiMe₃)₂}₂(THF)₂][B(C₆F₅)₄] (2) was prepared by reaction of 1 and [HNMe₂Ph][B(C₆F₅)₄]. The catalyst 2/Al(iBu)₃ (ratio Al/Nd: 10/1) was highly active for butadiene polymerization. Copolymerization of butadiene and styrene was performed with the catalytic system Nd{N(SiMe₃)₂}₃/[HNMe₂Ph][B(C₆F₅)₄]/Al(iBu)₃ (3). Copyright © 2004 Society of Chemical Industry     

Oxidation behavior of isoprene polymers and butadiene polymers

The oxidation behavior of cis-1,4-polyisoprene, emulsion polyisoprene, emulsion isoprene/styrene copolymers, and emulsion butadiene/styrene copolymers by heat aging or ultraviolet irradiation has been investigated from the change of gel fraction and molecular weight distribution. It was determined that the oxidation behavior of both isoprene and butadiene polymers is strongly dependent on the composition of the polymers as well as on the microstructure of the polymers. In the case of oxidation by heat aging, the probability ratio of chain scission to crosslinking of both isoprene and butadiene copolymers increases gradually with increasing styrene fraction. In the case of oxidation by ultraviolet irradiation, isoprene copolymers show a remarkable increase in the probability ratio of chain scission to crosslinking, whereas butadiene copolymers show substantially no change with increase in styrene fraction. It was also demonstrated that both isoprene and butadiene polymers show a greater tendency for crosslinking with oxidation by ultraviolet irradiation than with oxidation by heat aging.     

Anionic copolymerization of butadiene and styryl-terminated polystyrene macromonomers

Summary For the preparation of graft copolymers of the type poly (butadiene-g-styrene), possibilities were investigated both of obtaining a living anionic copolymerization of butadiene and styryl-terminated polystyrene macromonomers and of assessing the necessary analytical prerequisites for determining the conversion. The course of this copolymerization can be observed by combining gravimetry with SEC. With the initiator system sodium tert-butoxide /n-butyl lithium there are only a few deviations from the statistically ideal course of copolymerization and the macromonomer is almost completely incorporated into the copolymer.     

催化乳液合成可溶性超支化聚合物的IFIRP法研究

描述了可进行催化乳液聚合合成可溶性超支化聚合物的一种新的聚合物合成过程——引发剂残片嵌入自由基聚合（IFIRP,Initiator-Fragment Incorporation Radical Polymerization）。分别以高浓度的偶氮二异丁酸甲酯（MAIB）和α-甲基苯乙烯（α-MS）为引发剂及阻聚剂,在十二烷基磺酸钠（SDS）和水及苯形成的乳液中,通过IFIRP过程,在70～80℃条件下将单体二异丁烯酸乙二酯（EGDMA）聚合反应3 h即可得到可溶性的超支化聚二异丁烯酸乙二酯纳米粒子聚合物。研究发现,当EGDMA、MAIB和α-MS浓度分别为1.0、2.0和2.0 mol/L时,到80℃为止未见到凝聚现象发生,生成可溶性聚合物的产率为44%左右,相对分子质量分布在1.2～1.5之间。分析结果表明共聚物的成分为（质量分数）：α-MS为57%,MAIB为24%,含双键的EGDMA为5%,不含双键的EGDMA为14%。     

混甲基苯酚钾作助引发剂的丁二烯负离子调节聚合

采用对环境友好,价格便宜的氢氧化钾和混甲基苯酚合成混甲基苯酚钾(ROK),并研究了以其作助引发剂,正丁基锂(n—BuLi)为引发剂,二乙二醇二甲醚(2G)为极性添加剂,二甲苯为溶剂兼链转移剂的丁二烯负离子调节聚合,考察了ROK在不同有机溶剂中的溶解性和ROK用量对调聚的影响规律。结果表明,ROK在溶剂中的溶解度从大到小的顺序依次为2G,THF,乙醚,甲苯;随ROK用量的增加,聚丁二烯相对分子质量呈指数下降,链转移数超过50,说明ROK具有较好的调聚效果.     

Anionic polymerization of acrylates

Summary The article presents preliminary results of the anionic polymerization of 2-ethylhexyl- and butyl acrylates initiated by ester enolate in the presence of Li 3-methylpentoxide-3. Compared with the Li t-butoxide which has been widely used earlier, this alkoxide is a more efficient stabilizer of active centers. Under selectively chosen reaction conditions, polymerizations of both monomers proceed quantitatively with a small extent of the selftermination event at-40 and-20°C producing polymers with narrow MWD's.     

Anionic polymerization of vinylsilanes

Summary The anionic polymerization of dimethylphenylvinylsilane with sec-butyllithium/N,N,N,N-tetramethylethylenediamine (TMEDA) was investigated. The polymerization proceeded up to 100% yield and afforded the polymer having isomerized-structure units. The polymerization was accompanied by chain transfer reaction to the monomer and the polymerization rate in the presence of TMEDA was much lower than in the absence of TMEDA.     

不对称醚存在下丁二烯负离子聚合动力学

研究了以丁基锂为引发剂，4种新型不对称醚为调节剂，环己烷为溶剂的丁二烯负离子均聚。结果表明，4种新型不对称醚（GBSE，GBIE，GBCE，GBPE）均未发现有失活现象存在，且它们对丁二烯聚合速率的影响由大到小依次为：GBIE，GBSE，GBCE，GBPE。     

以环氧大豆油为偶联剂的丁二烯负离子均聚合

研究了以正丁基锂为引发剂,四氧呋喃（THF）为调节剂,环己烷为溶剂,环氧大豆油为偶联剂的丁二烯负离子均聚合。结果表明,随着偶联剂和THF用量的增加。偶联效率都是先升高后降低;随着温度的升高,偶联效率升高;偶联后聚合物相对分子质量分布变宽。     

乙二醇二乙氨基乙基丁基醚存在下的丁二烯负离子聚合

研究了以乙二醇二乙氨基乙基丁基醚(GABE)为调节剂,正丁基锂为引发剂的丁二烯负离子聚合的聚合动力学及聚合物的微观结构。结果表明,随着GABE用量的增加,丁二烯的聚合速率增加,聚丁二烯中1,2-结构质量分数增加,聚合温度升高,聚合速率增加,但聚丁二烯中1,2-结构质量分数有所降低。     

Anionic telomerization of butadiene with toluene and diphenylmethane: microstructure and molecular weight

The frequency of chain transfer of polybutadienyllithium to toluene and diphenylmethane is increased in the presence of N, N, N′, N′-tetramethylethylenediamine. When the reactor is fed with monomer at a constant rate, the molecular weight of telomer falls steeply as the ratio [base]:[lithium] increases from zero to unity but much more slowly thereafter. Whenever an anionic chain end has a penultimate 1,2-placement, cyclization to form a vinylcyclopentane competes with propagation the more favourably the lower the monomer concentration. In consequence, telomers prepared in toluene have a far greater cyclic content than those prepared in diphenylmethane.     

Anionic polymerization of methyl acrylate

The homogeneous polymerization of methyl acrylate in tetrahydrofuran using a variety of sodium aryl catalysts has been investigated at ?75°C and ?30°C. The mode of action of each catalyst is discussed and its efficiency in producing high polymer has been calculated from the yields and polymer characteristics. Sodium trityl is the most effective catalyst at both temperatures. Dilatometry has shown that with sodium naphthalene at ?70°C, rapid initial polymerization to about 10% conversion in 4 min is followed by a very low rate period which proceeds at low temperature for at least 24 h when conversions up to 50% have been observed. Throughout this period a species is present which absorbs at 320 nm and which is immediately lost on addition of a proton donor. There is evidence suggesting that this dormant form of the poly(methyl acrylate) anion is an oxyanion. It is postulated that carbanions are formed initially and are responsible for the rapid polymerization rate. They also isomerize in an equilibrium reaction to form the unreactive oxyanions. The rate of further propagation is thus controlled by the value of the equilibrium constant which in this system is strongly in favour of the oxyanions. On the basis of this mechanism some rate constants have been calculated.