Preparation of multifunctional organolithium initiator in cyclohexane solutions

Multifunctional organolithium initiator was prepared in cyclohexane solvent.The process started with adding the cyclohexane solution of butadiene to naphthalene-lithium in batches to produce butadiene oligomer dilithium with 4-8 butadiene repeating units.In the first feeding,the maximum loading of cyclohexane and the minimum concentration of butadiene cyclohexane solution must be controlled under V_cyclohexane≤1.33V_THFand p≥40.6C_N.Then,SnCl₄ was added and eventually the multifunctional organolithium initiator containing Sn atom was synthesized through coupling reaction. Experiment results showed that adding the cyclohexane solution in batches was effective in overcoming some difficulties, such as insolubility of naphthalene-lithium in cyclohexane,low efficiency of naphthalene-lithium in initiating butadiene.In practice,benzene can be replaced by cyclohexane completely,which can not only reduce environmental pollution from benzene,but also overcome the difficulty of solvent recovery caused by similar boiling point between benzene and cyclohexane.Prepared with multifunctional organolithium containing Sn atom as initiator,the star-shaped solution polymerized styrene-butadiene rubber（star S-SBR）with better vulcanization performances,lower rolling resistance and higher wet-skid resistance was obtained.     

Synthesis and characterization of star-comb styrene/butadiene copolymer

<正>A novel star-comb styrene/butadiene copolymer(SC-SBC) was synthesized by anionic polymerization and grafting reaction with epoxidized star liquid polybutadiene(ESPB) as coupling agent.The overall shape of the star-comb macromolecules can be altered by changing the molecular weight and number of the side chain.The molecular parameters and mechanical properties of the SC-SBC resins were investigated.The notched izod impact strength of the SC-SBC resins are excellent and reach as high as to 239 J/m.     

Synthesis and Characterization of Star-branched Polyisobutylene by Combination of Anionic Polymerization and Cationic Polymerization

The construction of polymer materials with controlled compositions, topologies, and functionalities has been the enduring focus in current research1,2. Among them, star polymers have been extensively studied for a long time, due to their markedly lower so…     

丙烯酰氯对丁苯共聚物活性链偶联反应的研究

以n BuLi为引发剂 ,四氢呋喃 (THF)为调节剂 ,抽余油为溶剂 ,采用丙烯酰氯为偶联剂对丁二烯 苯乙烯阴离子共聚体系进行偶联反应 ,研究了影响偶联反应的各种因素 ,如偶联剂用量、相对分子质量、偶联反应时间、偶联反应温度、THF用量、末端基团、单体浓度等 ;确定了偶联剂用量与聚合物相对臂数之间的关系及其偶联效率 .     

机理转移法合成聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)两亲性嵌段共聚物

将活性负离子聚合与原子转移自由基聚合(ATRP)技术相结合,运用机理转移法制备了一种两亲性材料聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)(PB-b-PDMAEMA)嵌段共聚物.首先通过负离子聚合方法设计合成聚丁二烯,用环氧丙烷封端,2-溴异丁酰溴作酯化剂,合成具有活性端基溴的聚丁二烯大分子引发剂(PB-B r),再用其引发亲水性单体DMAEMA进行原子转移自由基聚合,聚合动力学证实了该聚合反应具有典型的活性/可控自由基聚合的特征.通过差示扫描量热法(DSC)研究嵌段共聚物的微相分离行为.制备的大分子引发剂及两亲性嵌段共聚物经凝胶色谱、红外和核磁表征证实了预定的结构.     

微孔对HDPE缺口冲击强度及断面形貌特征的影响研究

在-196℃～+23℃的温度范围内,系统测试了微孔发泡和未发泡高密聚乙烯(HDPE)的Izod缺口冲击强度,进行了动态粘弹谱(DMA)和冲击断口系统观察分析.根据实验结果,研究了外加冲击力场作用下微发泡高密度聚乙烯变形断裂过程和机理,揭示了微孔的存在导致一定实验温度下的材料变形断裂机制发生了变化,微孔的引入一方面减小了试样(材料)的有效承载面积,另一方面导致HDPE试样芯部基体材料的应力状态改变为平面应力状态,易于在冲击载荷下产生塑性变形或在低温脆断条件下裂纹尖端钝化阻止裂纹扩展,其综合作用的结果导致微孔发泡和未发泡HDPE的Izod缺口冲击强度随实验温度的变化规律存在差异,且实验温度高于-35℃时,微孔发泡HDPE的缺口冲击强度低于未发泡的,实验温度低于-35℃后,微孔发泡HDPE的缺口冲击强度高于未发泡的.     

(n-BuCp)_2TiCl_2/Sn/I_s引发合成梳形羟基功能化无规聚苯乙烯及聚合物结构与性能的研究

采用茂金属化合物(n-BuCp)2TiCl2,还原剂(Sn),引发剂苯基缩水甘油基醚甲醛共聚物(Is)组成的催化体系引发苯乙烯活性自由基聚合,合成梳形羟基功能化无规聚苯乙烯.考察了聚合温度、聚合时间及引发剂与单体的比例对苯乙烯聚合的影响.当聚合温度在65～95℃范围内,随着聚合温度的升高,聚合物的分子量及单体转化率增加;在一定温度下,聚合物的分子量与单体转化率之间存在线性增长关系,且聚合物的分子量分布较窄(Mw/Mn=1.6～1.9).采用GPC,WAXD,13C(1H)-NMR对聚合物(沸丁酮可溶级分)的结构与性能进行了表征.GPC结果证明(n-BuCp)2TiCl2/Sn/Is引发苯乙烯聚合为活性聚合;13C-NMR和WAXD结果说明聚苯乙烯链段为无规结构;1H-NMR结果表明聚合物分子链中含有羟基,并根据其结果计算出聚合物分子的臂数为4,与引发剂Is的环氧基团数相等.这些结果证明了其聚合机理是经环氧基团开环后形成的自由基引发苯乙烯自由基聚合.     

Dynamically Photocrosslinking of Polypropylene／EPDM Blends as a Thermoplastic Elastomer

The mechanical properties and the crystal morphological structures of the dynamically photocrosslinked polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) blends have been studied by means of mechanical tests, wide-angle X-ray diffraction(WAXD), and differential scanning calorimetry(DSC). The dynamically photocrosslinking of the PP/EPDM blends can improve the mechanical properties considerably, especially the notched Izod impact strength at low temperatures. The data obtained from the mechanical tests show that the notched Izod impact strength of the dynamically photocrosslinked sample with 30% EPDM at -20℃ is about six times that of the uncrosslinked sample with the same EPDM component. The results from the gel content, the results of WAXD, and the DSC measurements reveal the enhanced mechanism of the impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (1) There exists the crosslinking of the EPDM phase in the photocrosslinked PP/EPDM blends ; (2) The β-type crystal structureof PP is formed and the content of α-type crystal decreases with increasing the EPDM component; (3) The graft copolymer of PP-g-EPDM is formed at the interface between the PP and EPDM components. All the above changes of the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of the PP/EPDM blends at low temperatures.     

Synthesis and Characterization of ABBA Block Copolymer of Glycolide and ε-Caprolactone

A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.     

Application of online near infrared spectroscopy to study the kinetics of anionic polymerization of butadiene

Online Fourier-transform near infrared (FT-NIR) spectroscopy in combination with a fiber optic probe was utilized to study the kinetics of the anionic polymerization of butadiene. The conversion of the butadiene to methylene protons in the polymer was monitored in solution polymerization conditions by monitoring the absorbance at 1632 nm. The off-line gel permeation chromatography, GPC, technique was used to validate the online FT-NIR spectroscopy method. Butadiene polymerization kinetics in cyclohexane initiated with n-butyllithium at different initiator concentrations and temperatures was studied. A phenomenological kinetic expression for the anionic polymerization of butadiene in cyclohexane initiated with n-butyllithium was determined. The predictions of the kinetic expression were in agreement with kinetic data reported in the literature.     

SYNTHESIS, CHARACTERIZATION AND RING-OPENING POLYMERIZATION OF CYCLIC (ARYLENE PHOSPHONATE) OLIGOMERS

INTRODUCTIONThe use of cyclic oligomers as macrocyclic precursors for the preparation of high performance polymers byring-opening polymerization (ROP) has sparked much interest in recent years. It could produce a revolutionarychange in the preparation of advanced composite materials, and is of great importance in the polymerizationprocess yielding polymers such as the reinforced reactive injection model (RRIM) and the resin transfer model(RTM) etc. Within the last 10 years, the synthes…     

甲基丙烯酸酯的基团转移嵌段共聚研究

甲基丙烯酸酯的基团转移嵌段共聚研究戴李宗邹友思陈良坦潘容华（厦门大学化学系厦门３６１００５）关键词基团转移聚合，甲基丙烯酸酯，嵌段共聚物，结构表征基团转移聚合［１］（ＧｒｏｕｐＴｒａｎｓｆｅｒＰｏｌｙｍｅｒｉｚａｔｉｏｎ，ＧＴＰ）具有活性聚合的特点...     

机理转移法合成星形梳状聚丁二烯-g-聚甲基丙烯酸甲酯共聚物的研究

结合活性负离子聚合与原子转移自由基聚合(ATRP),采用机理转移法制备了一系列窄分布且分子量可控的星形梳状聚丁二烯-g-聚甲基丙烯酸甲酯接枝共聚物(SC-(PB-g-PMMA)).首先通过阴离子聚合,制备星形聚丁二烯,后经甲酸-过氧化氢原位环氧化对链中部分双键进行环氧化,再与原位生成2-溴异丁酸发生酯化反应,得到具有链中活性溴的星形大分子引发剂(SPB-Brn).然后,利用该大分子引发剂,采用CuCl/CuCl2/PMDETA催化体系,通过ATRP聚合单体MMA,合成出星形梳状SC-(PB-g-PMMA)聚合物.通过GPC,1H-NMR和FTIR等分析手段对合成的星形大分子引发剂及星形梳状聚合物进结构表征,证实得到目标产物,并同时研究了聚合物的热力学性质与溶液性质.     

Arrangement of C60 via the Self‐Assembly of Post‐Functionalizable Polyisocyanate Block Copolymer

Poly(furfuryl isocyanate) (PFIC), which includes the reactive furan group, was synthesized by anionic polymerization using a sodium benzhydroxide (Na‐BH), self‐assembly initiator. We determined the optimum polymerization conditions by varying both the reaction time and the molar ratio of the monomer to the initiator. Block copolymer, poly(furfuryl isocyanate)‐b‐poly(n‐hexyl isocyanate), was synthesized under optimized polymerization conditions. The PFIC was modified by Diels–Alder reactions with C60 for functionalization. Transmission electron microscopy (TEM) was used to study the self‐assembly of block copolymers and modified block copolymer with C60. C60 formed highly ordered aggregates on the PFIC domains via self‐assembly of the block copolymer.     

Catenated PS–PMMA Block Copolymers via Supramolecularly Templated ATRP Initiator Approach

A novel route to synthesize catenated macrocyclic PS–PMMA block copolymers is demonstrated via combination of supramolecular chemistry and controlled radical polymerization (CRP). Polymerization of styrene with bromopropionate ester initiator coupled with phenanthroline Cu(I) complex affords a four arm PS macroinitiator, which upon further chain extension by polymerization of MMA generates a four arm PS–PMMA block copolymer. Intramolecular coupling of PS–PMMA–Br arms via low temperature styrene‐assisted atom transfer radical coupling (ATRC) leads to the formation of PS–PMMA catenand, which generates the metal‐free catenated macrocyclic PS–PMMA block copolymer after removal of Cu metal. The interlocked structures of catenated block copolymers are confirmed by GPC, NMR, and AFM image analysis.     

聚丁二烯1,2-结构含量和SBS中聚丁二烯段1,2-结构含量的调节

以正丁基锂为引发剂,环己烷为溶剂,研究了四氢呋喃(THF)对聚丁二烯1,2-结构和丁苯嵌段共聚物SBS中聚丁二烯段1,2-结构含量的影响,指出在一定温度下,聚丁二烯1,2-结构含量与体系中THF的浓度有指数关系。控制体系中THF的浓度和聚合反应温度,可调节聚合产物中聚丁二烯1,2-结构含量。     

Synthesis and characterization of a film‐forming,crosslinked, amphiphilic block copolymer of butadiene and acrylamide

An amphiphilic block copolymer of acrylamide and butadiene was synthesized by the polymerization of acrylamide in the presence of the crosslinker N,N′‐methylene bisacrylamide initiated by a hydroxyl‐terminated polybutadiene/V(V) macroredox initiator. The product had good film‐forming ability. It was characterized by IR and NMR spectroscopy, viscosity, swelling, and microhardness measurements, scanning electron micrography, and differential scanning calorimetry. A good film was obtained from the block copolymer with a greater proportion of butadiene; it had greater permeability for nonpolar solvents, and it was poorly permeable to water and other polar solvents. The film swelled in polar and nonpolar solvents and had almost the same capacity for the loading and release of hydrophilic and hydrophobic dyes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3290–3303, 2006     

用双硫酯链转移法合成嵌段聚合物

研究了以双硫酯为链转移剂进行的均聚和嵌段共聚物的合成 .首先合成大分子链转移剂 ,得到分子量可控、多分散性系数较小的均聚物PMMA、PBMA、PEMA、PEA、PBA、PMA、PSt,多分散性系数一般小于 1 30 .在相同的条件下 ,甲基丙烯酸酯类的聚合速度最快 ,苯乙烯其次 ,丙烯酸酯类最慢 .用末端带有双硫酯基团的PSt、PBMA、PBA为链转移剂 ,加入多种第二单体聚合得到实测分子量与理论分子量接近 ,且多分散性系数较小的两嵌段聚合物 .在链转移剂和引发剂的比例为 3∶1～ 6∶1的范围内 ,聚苯乙烯同样可以作为第一嵌段得到和其它酯类单体的两嵌段聚合物 .1 H NMR方法证明了聚合物的末端带有双硫酯基团 .嵌段聚合时必须加入微量的自由基引发剂以形成大分子自由基 ,达到较好的控制聚合效果     

Anionic High Impact Polystyrene: A New Process for Low Residual and Low Cost HIPS

BASF has developed a new process for the manufacturing of High Impact Polystyrene (HIPS) via an anionic route: the so-called A-HIPS process. The driving forces were the development of a product with a low content of residuals and improved cost performance compared to the radical state of the art HIPS. The production of A-HIPS includes the synthesis of the rubber, a styrene-butadiene block copolymer. To overcome the main challenges of anionic polymerization such as reactivity control, solvent purity and initiator costs, BASF has developed its own proprietary technology, the Retarded Anionic Polymerization (R.A.P.) which allows styrene polymerization to 100% conversion under similar reaction conditions as the radical polymerization. A new low cost anionic initiator system (BuLi-free), based on sodium hydride and triethylaluminum, has been developed for perfect reactivity control over a broad temperature and concentration range even up to bulk conditions.     

Anionic polymerization of a fluorinated butadiene

1,1-Bis(trifluoromethyl)-1,3-butadiene (I) is cleanly prepared in three steps. I produces an amorphous polymer by free-radical catalysis. Crystalline poly-I is produced by butyllithium catalysis in tetrahydrofuran at ?78°C. Qualitative kinetic experiments indicate that the anionic polymerization proceeds by a “living polymer” process. An AB block copolymer may be formed by adding I to anionically propagating butadiene; however, the reverse does not occur.