Synthesis and characterization of miktoarm star copolymer of styrene and butadiene using multifunctional macromolecular initiator

A new kind of multifunctional macromolecular initiator with Sn-C bonds and polydiene arms was synthesized by living anionic polymerization.At first,polydiene-stannum chloride(PD-SnCl_3) was prepared by the reaction of n-butyl-Li(n-BuLi),stannic chloride(SnCl_4) and diene.Then PD-SnCl_3 was used to react with the dilithium initiator to prepare the multifunctional organic macromolecular initiators.The result suggested that the initiators had a remarkable yield by GPC,nearly 90%.By using these multifunction...     

过程控制对反应挤出苯乙烯/丁二烯共聚物微观结构的影响

在有机锂引发体系下,以双螺杆挤出机为反应器,苯乙烯(St)、丁二烯(Bd)混和物作为单体,四氢呋喃(THF)为极性调节剂,本体法一步合成了苯乙烯/丁二烯(S/B)共聚物.采用过氧化氢在四氧化锇作用下对聚合物分子链中Bd双键进行了深度氧化降解,通过精制除去降解的低分子产物.利用18角度小角激光光散射仪联用GPC对降解前后的样品进行分析.结果表明与通常规律相左,THF的加入使共聚物的分子量分布加宽,同时使降解后的聚苯乙烯(PS)第一嵌段分子量降低.由1H-NMR谱图计算得知,THF使1,2-聚丁二烯(PBd)比例明显增加,但THF/引发剂摩尔比值超过一定量后,1,2-PBd含量增加趋势减缓.TEM分析结果表明THF的加入导致PBd相尺寸变小而且分布趋向均匀,再次表现出过程控制分子结构的特色.     

反应挤出法合成S/B多嵌段共聚物的研究

在阴离子引发体系下 ,以双螺杆挤出机为反应器 ,采用丁二烯、苯乙烯混和单体加料方式 ,本体法一步合成了S B多嵌段共聚物 .考察了螺杆转速、进料速率以及不同丁苯配比对反应挤出合成PS及S B嵌段共聚物聚合转化率的影响 .用1 H NMR、IR、DMA、TEM等方法对S B嵌段共聚物进行了表征 ,结果表明共聚物由多个微小的丁二烯嵌段和少量无规段组成 .当丁二烯含量少至 15 %左右时 ,其嵌段可回缩成球状 ,粒径大约在 30～ 5 0nm .该材料的韧性随着共聚物中丁二烯含量的增加而逐渐提高 ,特别是断裂延伸率的提高尤为显著     

用~(13)CNMR研究丁苯阴离子共聚体系中各活性种的竞聚率

本文利用~(13)CNMR测试数据,计算了丁苯阴离子共聚体系中各活性种的竞聚率,得到了与动力学数据较一致的结果,对阴离子聚合反应Markov级数问题进行了讨论,并对用积分法计算高转化率下共聚物二元组组成进行了探索。     

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.     

苯乙烯/丁二烯聚合反应挤出多嵌段共聚物结构表征及共聚机理的研究

以双螺杆挤出机为反应器,采用丁二烯(B)与苯乙烯(S)混和单体,以有机锂为引发体系,本体一步合成了S B多嵌段共聚物.采用过氧化氢在四氧化锇作用下对聚合物分子链进行了深度氧化,然后通过精制除去氧化降解产生的低分子物.1H- NMR和FT IR分析表明共聚物中的双键全部被氧化断裂,而共聚物中聚苯乙烯的链节并未破坏.利用18角度小角激光光散射仪(MALLS)联用GPC对氧化降解后的聚苯乙烯碎片进行了分析,证明共聚物分子是由1条1×104～4×104分子量的聚苯乙烯链段连接着数十个(S- B)嵌段的结构.TEM分析表明调节反应过程的工艺条件可以控制共聚物的织态结构.     

采用反应挤出三次加料法合成苯乙烯/异戊二烯/苯乙烯

以同向啮合双螺杆挤出机为反应器,采用苯乙烯和异戊二烯为聚合单体,以正丁基锂为引发剂,采用三次加料法合成苯乙烯/异戊二烯/苯乙烯(SIS)三嵌段热塑性弹性体.氢核磁共振(1H NMR)谱分析结果表明,共聚物中聚异戊二烯嵌段以1,4-结构为主.采用四氧化锇催化双氧水氧化降解聚合物分子链,利用凝胶渗透色谱对氧化降解后的聚苯乙烯碎片进行分析,证明共聚物分子为(聚苯乙烯-聚异戊二烯-聚苯乙烯)(PS-PI-PS)三嵌段结构.动态力学分析(DMA)及透射电子显微镜(TEM)分析结果表明,SIS具有两相分离结构.拉伸试验结果表明,共聚物拉伸强度与苯乙烯含量有关.     

Copolymerization of butadiene and styrene with neodymium naphthenate based catalyst

Copolymerization of butadiene (Bd) and styrene (St) was carried out in toluene at 50 °C by a conventional rare earth catalytic system, Nd(naph)₃-Al(i-Bu)₃-Al(i-Bu)₂Cl. It exhibited a high catalytic activity and high stereospecificity in the copolymerization. The influences of the conditions in polymerization on the yield, composition, microstructure and molecular weight of copolymer were thoroughly studied. According to the 13C-NMR spectrum, the resultant copolymer containing 18% St units, and the diad fraction of St-trans Bd or St-vinyl Bd can hardly be found in its 13C-NMR. The cis-1,4 content of Bd unit of the copolymer decreased little with the increase of St content. The GPC curves indicate the presence of two kinds of active sites in the polymerization.     

苯乙烯微乳液种子聚合

通过观测苯乙烯微乳液种子聚合前后体系内聚合物粒子大小及其分布的变化发现,无论是γ射线还是KPS引发,聚合过程中都没有新的聚合物粒子生成。尽管聚合前体系中存在单体溶胀的胶束,但在聚合过程中这些胶束主要充当单体仓库,自己成核聚合的几率很低。由于微乳液种子聚合体系内,单体量相对较低,聚合物粒子数目很大,其聚合动力学明显不同于常规乳液种子聚合。     

不同结构Iniferter引发苯乙烯聚合反应的研究

以不同结构的含氯化合物与铜试剂反应合成了4种链引发-转移-终止剂(Iniferter)。研究了它们引发苯乙烯的聚合反应过程,重点考察了Iniferter结构对聚合产物的影响。采用核磁共振氢谱和凝胶渗透色谱对聚合物分子量和分子量分布进行了测定。结果表明:Iniferter结构对聚合反应速率、分子量实测值与理论值间的对应关系及分子量分布均有明显影响,当其形成的初级自由基上带有使其稳定的基团时,引发效率就高,聚合反应速率较快,而且分子量理论值与实测值两者更接近。加入四甲基秋兰姆化二硫组成双组份Iniferter引发体系可以在一定程度上使聚合物分子量分布变窄。     

TEMPO调控下的苯乙烯光聚合

在UV光照射下, 以Irgacure 1103/TEMPO为引发剂, 实现了苯乙烯的低温光引发可控聚合, 得到了低分散性的聚苯乙烯. 与热引发聚合相比较, 光聚合的反应条件更温和, 聚合速率更快. 探讨了聚合体系中光引发剂及光强等因素的影响, 实现了光聚合产物的扩链反应.     

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 .     

2-溴代环己酮引发的苯乙烯原子转移自由基聚合

在铜体系催化的卤原子转移自由基聚合反应中 ,已有多种卤化物被作为引发剂使用 ,如α-卤代酯、α-卤代腈、多卤代烃、卤代苄基化合物及芳磺酰氯等 [1] ,最近又有报道称 N-氯代磺酰胺也可以作为引发剂使用 [2 ] .但以 α-卤代酮作引发剂只在钌系 [3～ 7]、铁系 [8]及镍系 [9]催化的原子转移自由基聚合中进行了研究 ,尤其是 Swawamoto等 [3～ 6] 对 Ru Cl2 (PPh3 ) 3 作催化剂 ,α,α-二氯苯甲酮和 1 ,1 ,1 -三氯丙酮作引发剂进行的甲基丙烯酸甲酯的原子转移自由基聚合进行了非常系统的研究 .由于羰基的吸电子能力较强 ,α-卤代酮的卤原子…     

Controlled/living radical polymerization of isoprene and butadiene in emulsion

A process for RAFT-controlled radical polymerization in emulsion [36] has been applied to the polymerizations of isoprene and of butadiene in emulsion systems, with the goal of producing latex particles containing block copolymers of acrylic acid (stabilizer and starting polymer), styrene (second polymer) and isoprene or butadiene (third polymer). The microstructure of the polymer chains was examined using dual-detection size-exclusion chromatography, and the nanostructure of the materials was investigated by differential scanning calorimetry and solid-state nuclear magnetic resonance. Reactions were always slow (although faster than the corresponding processes in solution), and exhibited limited reinitiation by isoprene when in emulsion. The materials containing isoprene exhibit a nanostructure with a phase separation into high-T_g polystyrene-rich domains and low-T_g polyisoprene-rich domains, revealed by DSC and NMR. This has the potential to lead to barrier materials with novel physical properties.     

Preparation of rechargeable biocidal polypropylene by reactive extrusion with diallylamino triazine

Biocidal polypropylene (PP) was prepared by using a reactive extrusion process, in which PP was grafted with an N-halamine precursor, 2, 4-diamino-6-diallylamino-1, 3, 5-triazine (NDAM). After chlorination the grated PP was converted to biocidal halamine structures. Effects of monomer and initiator concentration on grafting yield, thermal properties, and biocidal efficacy were studied. The Fourier transformed spectroscopy (FTIR) results and nitrogen analysis confirmed the graft polymerization on PP backbone during the reactive extrusion. The results also indicated that at low monomer concentration, increase in initiator concentration led to increase in PP chain scission and decrease in mixing torque, or polymer chain length. As the monomer concentration increases, grafted monomer content in the products showed a steady increase, indicating more grafting copolymerization in the system. The halogenated products exhibited potent antimicrobial properties against Escherichia coli, and the antimicrobial properties were durable and regenerable.     

Study of low concentrations of dicumyl peroxide on the molecular structure modification of LLDPE by reactive extrusion

The effect of low concentrations of dicumyl peroxide (DCP) on the molecular weight of a linear low density polyethylene (LLDPE) during a reactive extrusion process was studied. The experiments were arranged in a two level factorial design in order to evaluate the effect of peroxide concentration (X₂), temperature zones (X₁) and screw rpm (X₃) on the crosslinking of LLDPE. The melt flow index (MFI) was used as a response variable. It was verified that the thermal properties, crystalline melting temperature (T_m), the heat of fusion (ΔH_melt) and the degree of crystallinity (X%) tend to decrease with increase of the peroxide concentration. The crystallization temperature (T_c) increased up to 0.5% w/w peroxide, whereafter the level stays almost constant. In this study, it was also verified through the dynamic rheological data that there was an increase of the complex viscosity and the complex modulus (G′ and G″). These results can be an indication that there was an increase of the polymer average molecular weight (M_w) and polydispersity (MWD). The gel content of the samples, however, indicated that a three-dimensional network was negligible in the experimental conditions used.     

Functionalization of polyesters with maleic anhydride by reactive extrusion

Maleic anhydride (MAn) was grafted onto aliphatic and aromatic/aliphatic copolyesters by reactive extrusion in the presence of a free radical initiator using a twin‐screw extruder. The grafting reaction was confirmed by spectroscopic analyses. The presence of succinic anhydride groups was shown by FT‐IR spectroscopy, and NMR spectra indicate that the grafts consist of single succinic anhydride units. The 2D ¹H‐NMR spectra (COSY) indicate that grafting reactions take place at aliphatic dicarboxylic acid units of copolyesters. The graft content was determined by a nonaqueous titration method. The effects of concentration of initiator and monomer and reaction temperature on the graft content and intrinsic viscosity were studied. The low percentage grafting in poly(lactic acid) was observed due to the presence of limited free radical sites in the polymer backbone. Temperature and monomer and initiator concentrations affect the graft content, and the desired graft content with minimal degradation can be obtained by controlling these factors. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1693–1702, 1999     

苯乙烯间规聚合进展

苯乙烯间规聚合在近１０年来得到迅速的发展。本文将综述用于苯乙烯间规聚合的催化剂、助催化剂以及聚合机理。     

丁二烯阴离子聚合动力学及活性种的研究

本文对于n-BuLi/2G引发的丁二烯阴离子聚合动力学数据及产物微观结构进行了解析。建立了动力学模型,提出了聚合反应机理。求得了单量体、一络合体和二络合体的增长速度常数和诸活性种之间的平衡常数以及它们对形成乙烯基结构的贡献。