极性调节剂对SSBR微观结构及聚合反应的影响

以正丁基锂为引发剂,以环己烷为溶剂,分别采用SDBS／THF、SDBS／PMDETA为复合调节剂,制备了溶聚丁苯橡胶（SSBR）;研究了极性调节剂对聚合反应速率和聚合物微观结构的影响。结果表明：复合调节剂可使聚合反应速率增加,并且使聚合物链中乙烯基含量和苯乙烯含量均匀分布,得到的产品是完全无规化的SSBR,相对分子质量分布大于1．6,从而对改善SSBR的性能起到了重要的作用。最终合成的SSBR具有良好的物理机械性能。     

结构调节剂对锂系溶聚丁戊橡胶微观结构的影响

以正丁基锂为引发剂,环己烷/己烷混合溶剂为溶剂,四氯化硅为偶联剂,THF(四氢呋喃)、ESM(乙二醇二基叔丁基醚)为极性调节剂,分别进行了均聚和丁二烯、异戊二烯共聚实验,研究了调节剂种类及用量对聚合物微观结构的影响。研究结果表明:改变调节剂的种类及用量,可改变聚合物中乙烯基结构含量;调节能力为ESM>>THF,反应得到无规共聚物。     

用1G／2G复合调节剂进行丁二烯阴离子聚合的研究

在环已烷中，以正丁基锂引发的丁二烯阴离子聚合，采用１Ｇ／２Ｇ复合调节剂，研究了１Ｇ／２Ｇ复合调节剂对聚丁二烯微观结构及聚合动力学的影响。实验结果表明：１Ｇ与２Ｇ复合调节剂对聚丁二烯微观结构的调节能力强于１Ｇ或２Ｇ单一调节剂。聚合速度与单体浓度呈一次方关系，并分别求得不同温度下的单体一级反应速度常数（Ｋ″ｐ）及表观增长活化能（Ｅ′ｐ）。     

不同极性调节剂对溶聚丁苯橡胶性能的影响

以正丁基锂为引发剂,环己熔为溶剂,ＴＨＦ,２Ｇ,ＴＭＥＤＡ为极性调节剂,ＳｎＣｌ４为偶联剂合成溶聚丁苯橡胶,研究了不同极性调节剂对ＳＳＢＲ性能的影响。结果表明,不同极性调节剂对ＳＢＲ的物理机械性能及动力学性能影响不同,ＴＨＦ作极性调节剂制备的ＳＳＢＲ的综合性最优。     

用复合调节剂进行丁二烯阴离子聚合

在环己烷溶剂中，以正丁基锂为引发剂，分别添加乙二醇二甲醚／四氢呋喃（１Ｇ／ＴＨＦ）、二乙二醇二甲醚（２Ｇ）／ＴＨＦ复合调节剂，对丁二烯阴离子聚合进行研究，考察了１Ｇ／ＴＨＦ、２Ｇ／ＴＨＦ复合调节剂对聚丁二烯微观结构及聚合动力学的影响。结果表明：１Ｇ／ＴＨＦ、２Ｇ／ＴＨＦ复合调节剂对合成锂系聚丁二烯橡胶是较方便、有效、具有实用价值的微观结构调节剂。聚合动力学研究表明，聚合速度与单体浓度呈一次方关系，     

极性调节剂对SSBR微观结构及性能的影响

以正丁基锂为引发剂,环己烷为溶剂,采用SDBS/THF为复合调节剂,制备了溶聚丁苯橡胶（SSBR）;研究了聚合物微观结构对聚合物性能的影响。结果表明：复合调节剂使聚合物链中乙烯基含量和苯乙烯含量均匀分布,得到的产品是完全无规化的SSBR,随着聚合物链中乙烯基含量和苯乙烯含量的增加,产品的玻璃化转变温度明显增加,产品的动态力学性能得到显著提高,分子质量分布大于1.6,合成的SSBR具有良好的物理机械性能。     

二烯类橡胶合成反应中的结构调节剂

综述了阴离子聚合反应中微观结构调节荆的发展历史、分类和特点，介绍了它们在聚丁二烯橡胶、聚异戊二烯橡胶、溶聚丁苯橡胶（SSBR）和苯乙烯／异戊二烯／丁二烯三元集成橡胶（SIBR）中的应用，着重介绍了各种微观结构调节荆对橡胶聚合物链中的聚丁二烯的1，2-结构和聚异戊二烯的3，4-结构的调节能力，并指出了结构调节荆今后的主要发展方向，即调节体系由一元体系向二元体系发展。调节荆分子结构由对称向不对称发展。     

聚合反应速率对ESBR结构与性能的影响

研究在工业丁苯装置中聚合反应速率对乳聚丁苯橡胶（ESBR）结构与性能的影响。结果表明，随聚合反应速率的增大，ESBR的重均相对分子质量增大，数均相对分子质量减小，相对分子质量分布变宽；ESBR分子链中苯乙烯链节比例略有提高，丁二烯链节中1，2-结构和顺式1，4-结构含量略有增大；ESBR生胶门尼粘度、硫化胶定伸应力和拉伸强度略有增大，拉断伸长率略有减小。     

Classification of polar additives with respect to their influence on the microstructure in anionic polymerization of isoprene with butyllithium by transition energy measurements

A transition energy scale was established on the basis of dimethyl indoaniline as organic dye for 23 mono- and bidentate polar additives. From polymerization experiments of isoprene with s-butyllithium in mixtures of n-hexane and the selected bases, the microstructure of polyisoprenes was determined by ¹H-NMR spectroscopy. The vinyl contents of these polymers could be satisfactorily correlated with the transition energy measurements. However, it turned out that especially bidentate bases do not fit into this scheme. Obviously, besides their influence on the polarity of the reaction solution, they exhibit special interactions with the growing centers. The developed correlations allow the prediction of 1,2- and 3,4-linkages in polyisoprenes from anionic polymerization of isoprene with butyllithium in polar solvents in the presence of low concentrations, also of bases hitherto not investigated. The temperature dependence of the microstructure can likewise be estimated. As in the case of butadiene, at least for weak bases, it was found that the vinyl contents depend primarily on the polarity of the reaction mixture determined by the base concentration and not on the molar ratio of base to initiator. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1533–1547, 1999     

异戊二烯／THF负离子聚合产物的微观结构

研究了２０～５０℃下,以ｎ－ＢｕＬｉ为引发剂,环己烷为溶剂,ＴＨＦ为极性调节剂的异戊二烯负离子聚合产物的微观结构。结果表明：随聚合温度升高,聚异戊二烯的３,４－结构含量降低;在同一温度下,随ＴＨＦ用量的增加,３,４－结构含量增加。［ＴＨＦ］／［ｎ－ＢｕＬｉ］（Ｒ,摩尔比）大于１２时,才会出现１,２－结构,且聚合温度越高,出现１,２－结构时的Ｒ值越高,并随Ｒ值的继续升高,１,２－结构含量也不断增加。此外,还建立了４个微观结构含量与ＴＨＦ用量的定量关系式。     

Synthesis of highly isotactic (mm > 0.70) polyacrylonitrile by anionic polymerization using diethylberyllium as a main initiator

An attempt was made to synthesize steroregular polyacrylonitrile (PAN) with a high triad isotacticity (i.e. the content of mm (m, meso)) exceeding 0.70 by the anionic polymerization method. In the stereospecific polymerization of acrylonitrile (AN) initiated by diethylberyllium (Et₂Be) in xylene at 130°C, the (mm) content as well as the viscosity-average molecular weight (MÞ_v) of PAN increased by addition of diisobutylaluminum hydride (i-C₄H₉)₂AlH) as an additive to the polymerization system. Maximum (mm) content, attained in the molar ratio region of (i-C₄H₉)₂AlH/Et₂Be > 1.0, was about 0.73. The stereospecific polymerization of AN was also initiated using a mixture of Et₂Be and di-n-hexylamagnesium ((Et₂Be/(n-C₆H₁₃)₂ Mg system), where both Et₂Be and (n-C₆H₁₃)₂ Mg can induce the stereospecific polymerization of AN at 130°C. The (mm) content of the PAN sample prepared using the Et₂Be/(n-C₆H₁₃)₂ Mg system ((mm) = 0.64) was higher than that of PAN samples synthesized using Et₂Be alone ((mm) = 0.56) and (n-C₆H₁₃)₂Mg alone ((mm) = 0.51) under the same conditions except initiator. A significant difference in ¹³C chemical shifts of α-carbons between Et₂Be (1.35 ppm) and (n-C₆H₁₃)₂Mg (10.72 ppm) dissolved in hydrocarbon solvent at 110°C leads us to the conclusion that when Et₂Be induces the stereospecific polymerization in the Et₂Be/(n-C₆H₁₃)₂Mg system as initiator, the main role of (n-C₆H₁₃)₂Mg is considered to be the suppression of the association of Et₂Be (active site) itself.     

异戊二烯—环己烷—乙醚体系负离子聚合产物的微观结构

研究了在１５－３０℃下,以正丁基锂为引发剂,环己烷为溶剂,乙醚为极性调节剂的异戊在负离子聚合产物的微观结构。结果表明：在同一乙醚／正丁基锂摩尔比值下,随聚合温度升高,试样的３,４－结构摩尔分数降低;在同一温度下,随乙醚用量的增加,３,４－结构摩尔分数增加;以乙醚为极性添加剂时,聚合物分子链上含有３,４－和１,４－结构,不含１,２－结构;以乙醚为溶剂时,聚合物分子 含有３,４－,１,４－及１,２－结     

异戊二烯在二氧六环中的负离子聚合动力学

研究了以正丁基锂为引发剂 ,异戊二烯在二氧六环溶剂中负离子聚合的动力学。结果表明 ,增长反应对单体浓度和引发剂浓度皆为一级反应 ,活化能为45.22kJ/mol,频率因子为4.832×108L/(mol·min) ,并求出了生成1,4 -结构、1,2 -结构和3,4 -结构产物的速率常数分别为2.77×1012exp( -74760/RT) ,9.82×106exp( -39190/RT) ,8.02×107exp( -41180/RT)。     

Piloting of anionic polymerization of styrene in tetrahydrofurant

Anionic polymerization of styrene in THF with n‐butyllithium/alpha‐methylstyrene initiator is described as a first step in preparation of a styrenic block copoly‐mer. In order to suppress rapid decay of living alpha‐methylstyrene unimers, which occurred at room temperature, the initiation reaction was carried out at ?20(+5)°C. The kinetic parameters of this decay reaction were determined and used for process optimization. By combining experiments with modelling of styrene propagation reaction all key process parameters were defined for l‐L, 38‐L, and 189‐L reactors. A good match was demonstrated between the model and experimental propagation exotherm for semibatch reaction conditions. Overall, it was demonstrated that technical grade THF and styrene could be used at pilot plant scale to prepare well‐defined polymers up to Mn 22 000 via the “living” polymerization mechanism. The resulting polymers had narrow molecular weight distributions (1.06 < Mw/Mn < 1.30).     

异戊二烯在环己烷-二氧六环中的负离子聚合机理

推导了异戊二烯在环己烷－二氧六环混合剂中的负离子聚合机理,并通过实验进行了验证。研究表明,丁二烯聚合机理原则上同样适用于异戊二烯的负离子整合,推导出非1,4－结构产物含量与极性添加剂用量的关系式为1g[(a-b)/(xv-b)-1]=nlg[PA] lgK‘,求得了a,b,n,K′与温度的关系式,并指明了各自的物理意义。     

Synthesis of well-defined block copolymers of n-hexyl isocyanate with isoprene by living anionic polymerization

n-Hexyl isocyanate (HIC) was polymerized at different reaction temperatures and times, using alkali metal naphthalenide, via anionic polymerization in THF. To prevent the formation of trimers, the polymerization of HIC was also performed utilizing sodium tetraphenylborate (NaBPh₄) as a common ion salt. As the reaction temperature decreases, yield of the polymer increases due to stabilization of the active amidate anion at low temperature. In the absence of the additive, a quantitative yield was obtained at −98 °C. However, after most of the monomer was polymerized, further reaction led to trimerization. This was prevented in the presence of NaBPh₄ effectively and the living polymerization was performed successfully at −98 °C. The reaction rate retarded with increasing concentration of NaBPh₄, the optimum concentration of NaBPh₄ was 10 times the concentration of the initiator for the living polymerization of HIC. The living system led to the polymers of molecular weight (MW) as high as 50,000 g/mol. The observed MW was well in agreement with the calculated one. At the higher reaction temperature, −78 °C, the quantitative yield was obtained at 2 min of the reaction time, however the living character was not observed at longer reaction time. The study indicated that the amidate anion was stabilized using NaBPh₄ having bulky contact ion pair. The block copolymer of HIC with isoprene, poly(HIC-b-isoprene-b-HIC), was synthesized with help of the living character of polyisoprene and NaBPh₄. The morphology and composition of the block copolymers were investigated using TEM and ¹H NMR, respectively.     

Anionic polymerization of (meth)acrylic monomers: anionic polymerization of tert-butyl methacrylate in toluene

The anionic polymerization of tBMA initiated by an organolithium compound in toluene at low temperature (−78 °C and 0 °C) has been revisited. Under these experimental conditions, no ‘livingness’ is reported, consistently with formation of an important fraction of oligomers (M_n = 650). © 1999 Society of Chemical Industry