嵌段-接枝共聚物SEPG与PS(OH)之间的氢键络合导致胶束化的研究

利用原子转移自由基聚合反应合成了以聚苯乙烯-b-聚(乙烯-co-丙烯)(SEP)为主链、无规分布且数目可控的聚甲基丙烯酸乙酯(PEMA)为支链的嵌段接枝共聚物SEPG.发现在甲苯中因支链PEMA与聚(苯乙烯-co-对六氟羟丙基-α-甲基苯乙烯)[简称PS(OH]的氢键络合作用和EP嵌段的溶解作用导致了聚集体的胶束化.研究了胶束的尺寸及其分布对PS(OH)中羟基含量和共混物组成的依赖性.     

新型茂钛催化剂合成聚乙烯-b-间规聚苯乙烯嵌段共聚物的研究Ⅱ.嵌段共聚物的分离及结构性能

将五甲基茂基三苄氧基钛 (Cp Ti(OBz) 3) 改性甲基铝氧烷 (mMAO)催化体系以顺序加料溶液法合成的乙烯与苯乙烯嵌段共聚反应产物进行沸丁酮、沸四氢呋喃 (THF)和沸氯仿等溶剂连续抽提分离 ,发现嵌段共聚物主要存在于THF和CHCl3的可溶级分中 ,嵌段共聚物的总含量占共聚产物的 2 2 8wt%～ 38 2wt% ,对THF和CHCl3可溶级分分别用 1 3C NMR、WAXD、DSC和GPC等手段进行表征 .1 3C NMR谱显示出含有支化聚乙烯链段和间规聚苯乙烯链段的嵌段共聚物特殊结构 ,WAXD谱表明嵌段共聚物因两链段的相互缠结使各自结晶度显著较低 ,由于嵌段共聚物苯乙烯链段较长、乙烯链段较短 ,DSC图谱只显示苯乙烯链段的结晶熔融峰 ,GPC曲线表明 ,单茂钛催化体系催化乙烯 苯乙烯嵌段共聚合的单一活性中心特征 .由此对Cp Ti(OBz) 3 mMAO催化体系的苯乙烯 乙烯嵌段共聚合机理进行初探     

新型双核FI/α-二亚胺镍(Ⅱ)催化体系制备聚乙烯-b-聚(乙烯/1-辛烯)嵌段共聚物

合成了新型双核苯氧基亚胺锆催化剂(Cat B),并与α-二亚胺镍(Ⅱ)催化剂(CatA)构成催化体系,在助催化剂甲基烷氧铝(MAO)及链穿梭剂二乙基锌(ZnEt_2)作用下催化乙烯与1-辛烯共聚,制备了聚乙烯-b-聚(乙烯/1-辛烯)嵌段共聚物.采用差示扫描量热法(DSC)、傅里叶变换红外光谱(FTIR)及碳核磁共振波谱(13C NMR)等方法对聚乙烯-b-聚(乙烯/1-辛烯)嵌段共聚物进行表征.结果表明,在甲苯作溶剂的1.0 MPa和50℃条件下,MAO和金属活性中心的摩尔比为300∶1;1-辛烯加入量为0.58 mol/L时,CatB/CatA/ZnEt_2催化体系制备的产物中1-辛烯插入率为4.9%,DSC出现双峰,"软段"部分在聚合物链段中分布较为集中.     

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.     

等规聚苯乙烯与聚(乙烯/丙烯)嵌段共聚物的研究(Ⅱ)──嵌段共聚物的分离与表征

将配位聚合法合成的等规聚苯乙烯与聚(乙烯/丙烯)嵌段共聚反应产物进行溶剂车取分离,得到嵌段共聚物[iPS-b-Poly(E-co-P)]的含量约为总重量的20％～30％,并用¹³CNMR、FTIR、WAXD、DSC和电子显微镜进行表征．该共聚物是具有等规聚苯乙烯(iPS)与乙丙无规共聚链段结构的三元两嵌段共聚物,且iPS链段有一定的结晶度．由透射电镜可以看出,嵌段共聚物存在微相分离结构,相区尺寸在100nm数量级．     

稀土催化乙烯/苯乙烯链穿梭共聚合

链穿梭聚合作为一锅法合成多嵌段聚合物的策略引起人们的研究兴趣.然而,其催化体系的构建难度大,导致实现链穿梭聚合的单体有限.本文基于三异丁基铝作链转移剂时,稀土金属配合物1催化乙烯/苯乙烯共聚合,得到富含乙烯/苯乙烯交替序列的共聚物且链转移效率接近100%的发现,开展了乙烯/苯乙烯链穿梭聚合的研究.首先探索配合物2催化乙烯/苯乙烯共聚合,发现所得共聚物中苯乙烯结构单元的含量4%,因此考察了在不同烷基铝用量时,配合物2催化乙烯均聚合的行为,发现所得聚乙烯的分子量随着[Al]_0/[2]_0增加呈指数降低,幂指数为-0.778,表明链转移效率低于100%.采用1/2/Al~iBu_3三元体系催化乙烯/苯乙烯共聚合得到双峰分布的聚合物,说明链穿梭聚合没有实现.进一步筛选发现,配合物3催化乙烯/苯乙烯共聚合时,随着[Al]_0/[3]_0增加,所得富间规聚苯乙烯序列共聚物的分子呈量指数降低,幂指数为-1.097,接近-1,表明链转移效率接近100%;同时催化体系的TOF值减小.当[Al~iBu_3]_0/[1+3]_0≥20时,1/3/Al~iBu_3三元体系催化乙烯/苯乙烯共聚合得到单峰分布的乙烯/苯乙烯交替序列和富间规聚苯乙烯序列的多嵌段共聚物,说明成功实现了乙烯/苯乙烯链穿梭共聚合.通过调节1和3的比例,有效调控了共聚物中乙烯/苯乙烯交替序列和富间规聚苯乙烯序列的组成.     

超临界CO2中苯乙烯RAFT分散聚合

以末端带有三硫代碳酸酯的聚二甲基硅氧烷(PDMS-TTC)为大分子链转移剂,在超临界CO2中通过苯乙烯的可逆加成-断裂链转移(RAFT)聚合制备了聚二甲基硅氧烷-b-聚苯乙烯(PDMS-b-PS)嵌段共聚物,对聚合反应动力学以及产物的组成、分子量和形貌等进行了表征.由于PDMS链段可溶于超临界CO2而PS链段不溶,因此在超临界CO2中制备PDMS-b-PS嵌段共聚物的过程是以嵌段共聚物自身作为分散稳定剂的RAFT分散聚合,产物为粒径较均一的球形颗粒.     

以高顺式聚丁二烯为软段的三嵌段共聚物的制备

从高顺式端羟基聚丁二烯(HTPB)出发,分别以ε-己内酯和苯乙烯为单体合成了2类以高顺式聚丁二烯为软段的三嵌段共聚物.以高顺式HTPB为大分子引发剂、辛酸亚锡为催化剂,引发ε-己内酯的开环聚合,合成了聚己内酯-b-聚丁二烯-b-聚己内酯三嵌段共聚物(CLBCL);通过高顺式HTPB末端羟基与2-溴代异丁酰溴(BBi B)间的酯化反应制备了ATRP大分子引发剂(Bi B-PB-Bi B),进而引发苯乙烯进行电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)反应,合成了聚苯乙烯-b-聚丁二烯-b-聚苯乙烯三嵌段共聚物(SBS),反应具有较好的可控性,产物分子量分布较窄.通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)和碳谱(13CNMR)、热重分析(TGA)和示差扫描量热分析(DSC)等对所制备共聚物的结构和性能进行了测试表征.TGA曲线表明,提高聚己内酯链段的含量,可在一定程度上提高CLBCL共聚物的热稳定性;SBS共聚物的热分解过程表现为一个阶段,与HTPB相比,其热稳定性略有提高.从CLBCL共聚物的DSC曲线上可明显观察到聚丁二烯链段的玻璃化转变温度和聚己内酯链段的熔点;SBS共聚物具有2个玻璃化转变温度,为–104.1和102.4oC,分别对应于聚丁二烯链段和聚苯乙烯链段的玻璃化转变温度.     

用新型茂钛催化剂制备的苯乙烯/丁二烯嵌段共聚物的结构表征

用CpTi(OBz)3/MAO催化体系合成的苯乙烯／丁二烯嵌段共聚合产物经丁酮、甲苯、四氢呋喃、氯仿连续抽提,并用已烷对丁酮的可溶级分进行再抽提;不同级分分别用GPC、^13C -NMR、DSC和WAXD等手段进行分析和表征。发现嵌段共聚物主要存在于氯仿可溶级分中,丁酮可溶级分基本上是无规聚苯乙烯和聚丁二烯组成的混合物（己烷可溶级分为聚丁二烯,不溶级分为无规模聚乙烯）。GPS谱图表明该嵌段共聚反应具有单催化活性中心的聚合特征,^13C-NMR谱图显示该嵌段共聚物分子链由间规聚苯乙链段和聚丁二烯链段组成,WAXD图谱显示嵌段共聚物有较高的结晶度。     

以两亲性共聚物为模板溶胶-凝胶法制备WO3多孔薄膜及其 氢致变色特性的研究

报道了以六氯化钨为原料, 以两亲性的无规共聚物聚苯乙烯-co-聚烯丙醇(PS-co-PAAL)和三嵌段共聚物聚氧乙烯-b-聚氧丙烯-b-聚氧乙烯(PEO-b-PPO-b-PEO)为模板, 采用溶胶-凝胶法制备了WO3多孔薄膜. 利用热重分析仪(TGA)、粉末X射线衍射仪(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)等表征手段, 研究了模板和热处理温度对薄膜孔结构的影响; 并通过H2敏测试以及利用紫外可见分光光度计(UV), 研究了薄膜的氢敏性能和着色前后的透射光谱. 结果表明, 以无规共聚物PS-co-PAAL为模板制得的WO3薄膜, 经400 ℃热处理后, 可得到呈交联网状的多孔结构, 并表现出最佳的氢致变色性能.     

Influence of Metallocene Type on the Order of Ethylene Polymerization and Catalyst Deactivation Rate in a Solution Reactor

The solution polymerization of ethylene using rac-Et(Ind)₂ZrCl₂/MAO and (Dimethylsilyl(tert-butylamido)(tetramethyl- cyclopentadienyl)titanium Dichloride)(CGC-Ti)/MAO was studied in a semi-batch reactor at 120 °C under different monomer pressures and catalyst concentrations. The kinetics of ethylene polymerization with rac-Et(Ind)₂ZrCl₂/MAO can be described with first order reactions for polymerization and catalyst deactivation. When (CGC-Ti)/MAO is used, however, second order kinetics are observed for catalyst decay and the order of polymerization changes from 2 to 1 with increasing ethylene pressure.     

甲基铝氧烷的改性及其对乙烯聚合催化活性的影响

用BCl3为修饰剂制备了改性甲基铝氧烷(BMAO) 以二氯二茂锆为主催化剂、BMAO为助催化剂,考察了影响乙烯聚合活性的各种因素及其聚合动力学行为 与常用的甲基铝氧烷(MAO)相比,BMAO用于催化体系显著提高了乙烯聚合的催化活性.     

石墨烯/二氯化镁负载钛系齐格勒-纳塔催化剂制备及其乙烯聚合性能

石墨烯自2004年发现以来,由于其独一无二的优异性迅速成为科学家们的研究热点.由于石墨烯具有极其优异的电学、力学和热学等性能,因此被广泛应用于高性能聚合物基复合材料的制备.众所周知,纳米填料在聚合物中的分散状态以及与基体间的界面作用是构筑高性能聚合物纳米复合材料的关键因素.由于石墨烯极易团聚,难以通过传统的熔融共混法制备均匀分散的石墨烯增强-聚烯烃纳米复合材料.另一方面,聚烯烃通常需要在较高温度下才能溶于部分有毒溶剂(如:三氯苯和二甲苯等),因此溶液共混法也不适用于聚烯烃-石墨烯纳米复合材料的制备.有鉴于此,本文开发了一种共沉积法制备石墨烯/二氯化镁负载钛系齐格勒-纳塔催化剂的路线.通过原位聚合直接制备出石墨烯均匀分散的聚烯烃/石墨烯纳米复合材料.考察了石墨烯的加入量对催化剂形态及其催化乙烯聚合行为的影响.当石墨烯加入量较低时,多个石墨烯片被包裹于较大的催化剂粒子中.随着石墨烯加入量的增加,催化剂趋向于在石墨烯表面聚集.继续增加石墨烯量将导致石墨烯包裹催化剂粒子,降低过渡金属钛的负载效率.通过三乙基铝活化后,所制备的催化剂具有非常高的乙烯催化活性,所生成的聚乙烯/石墨烯纳米复合材料复制了催化剂的片状结构.同时,通过对所制备的聚乙烯/石墨烯纳米复合材料进行电子显微镜和X射线衍射分析可知,石墨烯均匀分散于聚乙烯基体中,并且没有任何团聚现象发生.该复合材料的热重分析表明,仅加入非常少量的石墨烯就可以使其具有比纯聚乙烯更高的热稳定性,当石墨烯加入量为0.66 wt%时,其5 wt%热分解温度较纯聚乙烯升高了54°C.同时,所制备聚乙烯/石墨烯纳米复合材料具有更优异的机械性能.因此,本研究提供了一个简单高效的高性能聚烯烃/石墨烯纳米复合材料的制备方法.     

In situ preparation of poly(ethylene terephthalate)-SiO2 nanocomposites

Poly(ethylene terephthalate) (PET)/silica nanocomposites were synthesized by using the in situ polymerization approach. Sol-gel transformation based on the hydrolysis and condensation of tetraethoxysilane (TEOS) is used to prepare the inorganic phase, concurrent with condensation polymerization of terephthalic acid and ethylene glycol to produce the PET matrix. Due to the simultaneous formation of the polymer matrix and the inorganic networks, a macrophase separation is avoided, and the resulting materials have a high degree of homogeneity. The morphology and the crystallization behavior of the composites were examined by scanning electron microcopy (SEM) and differential scanning calorimetry (DSC), respectively.     

Effect of Cu(II)/H2 Salen complex on the non-conventional initiated emulsion polymerization of acrylonitrile

Radical polymerization of acrylonitrile was carried out in an emulsifier-free condition initiated by KHSO₅ catalyzed with Cu(II)/bis-salicylidene ethylene diamine (H₂ Salen) complex. The Cu(II) salt alone, Cu(II)/salicylaldehyde and Cu(II)/ethylene diamine have a retarding effect on the polymerization reaction, while the chelate of Cu(II) with the tetradentate Schiff base ligand, H₂ Salen has a catalytic effect. Prior to this, the catalytic effect of various bivalent transition metal salts and their couple with the Schiff base, H₂ Salen on the polymerization reaction has been examined to be not significant. The in situ developed complex produces the stable emulsion leading to high conversion. In the polymerization, the variables studied were the concentration of monomer, initiator, Cu(II), H₂ Salen and temperature. The overall activation energy was computed to be 13.1 kcal/mol. From the kinetic and spectral analyses, the mechanism of the initiator decomposition and initiation of polymerization by Cu(II)/H₂ Salen complex were suggested. The rate of polymerization (R_p) was found to be dependent on the monomer, initiator, Cu(II) ion, H₂ Salen concentrations to the 1.4, 0.3, 1.6, 1.5 power respectively. The polymers are characterized by IR and molecular weight by viscosity and GPC methods.     

Novel Aluminoxanes Prepared from AlEt_3/Al(i-Bu)_3 Mixture as Cocatalyst for Metallocene Catalyzed Ethylene Polymerization

Methylalundnoxane(MAO)isthemostimportantcocatalystformetallocenecatalyzedolefinpolymerization.Intheearlyyearsofthefieldithadbeentheonlycocatalystwhichcanactivatemetallocenecatalyststoveryhighactivity.MAOispreparedbypartialhydrolysisofAl(CHs)s(TMA)undercontrolledconditions1.TMAisanextremelyreactiveanddangerousreagent,andthismakesMAOapreciouschendcalreagent.MAOaccountsforalargepercentageinthecostofthemetallocenecatalystsystem,becauseahighMAO/metalloceneratioisneededforpoIymerization'.I…     

Block copolymers prepared by emulsion polymerization with poly(ethylene oxide)–azo-initiators

Poly(ethylene oxide)-b-poly(styrene) block copolymers were prepared in the form of latex particles by emulsion polymerization of styrene with poly(ethylene glycol)–azo-initiators as well as with the redox initiation system poly(ethylene glycol)/Ce⁴⁺. The emulsion polymerization can be carried out in the absence of additional stabilizers if the chain length of the poly(ethylene glycol) is greater than 40. The latex particles as well as the copolymers were characterized by capillary hydrodynamic fractionation, ¹³C-nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy. By ¹³C-NMR spectroscopy a side reaction of the primary radicals arising from the azo-initiator was found which can contribute to the low efficiency of azo-initiators in emulsion polymerization.     

Ethylene polymerization catalyzed by nickel-based complex combined with various modified EBAOs

A series of novel aluminoxanes, ethyl-isobutylalulminoxanes (EBAO) modified with n-butaneboronic acid, phenylboronic acid and 4-fluorobenzeneboronic acid are synthesized. The ethylene polymerization activity of [diacetyl-bis(2,6-diisopropylanil)] NiBr₂(1)/different aluminoxanes were investigated. It is found that boronic acid greatly affects the catalytic activity of modified EBAO. Bulky substituted boronic site of EBAO improved ethylene polymerization activity of nickel complex.     

甲醇钠引发的环氧乙烷开环聚合反应过程

运用密度泛函理论(DFT)的Dmol3方法, 计算了甲醇钠引发的环氧乙烷开环聚合的反应过程. 并运用前线轨道理论对该聚合反应的各步反应历程进行了分析. 计算结果表明, 链引发为无能垒的放热反应, 放出的能量达到92.560 kJ·mol-1, 而链增长过程则需越过100.951 kJ·mol-1的反应能垒, 链增长物种与环氧乙烷的前线轨道相对称, 可以使开环聚合反应继续进行下去. 当向反应体系中加入草酸、磷酸等质子酸时, 会立即发生链终止反应. 此外, 还对链增长过渡态的合理性进行了确认, 绘出了相应的反应势能曲线.     

Compatible Polyethylene/Polyvinyl Chloride Particle Hybrids Prepared by in‐situ Polymerization

Polyethylene/polyvinyl chloride (PE/PVC) hybrids were successfully prepared by a polymerization‐filling method. The catalyst for ethylene polymerization was supported on PVC particles, and ethylene was then polymerized in‐situ on the surface of the activated PVC. PVC particles could be well segmented and dispersed during in‐situ polymerization, and the prepared hybrids had an additional tangent peak between the glass transitions of polyethylene and PVC, indicating the formation of a compatible interlayer between nascent polyethylene and PVC during polymerization.