短链支化聚乙烯的合成与表征

合成了两类结构明确的乙烯共聚物, 通过FTIR, GPC, ¹H NMR和¹³C NMR表征了产物的分子结构, 分别研究了分子量和短链支化含量对两类共聚物结晶性能的影响. 采用阴离子聚合制备分子量(M_w)20000~110000、分子量分布为1.1的1,2-结构摩尔分数为7%左右的聚丁二烯. 加氢反应后得到乙烯/1-丁烯模型共聚物的熔点和结晶度随着分子量的增加而下降. 采用茂金属催化剂Et[Ind]₂ZrCl₂催化乙烯与1-己烯共聚合, 制备分子量为100000左右, 共聚单体摩尔分数为0~5.5%的乙烯/1-己烯共聚物, DSC结果表明其熔点和结晶度随着共聚物中1-己烯含量的升高而降低.     

丙烯酰胺多面体低聚倍半硅氧烷在超临界CO2中的RAFT聚合

以超临界CO₂为聚合介质, 硫代苯甲酰基特丁基硫酯(TTBT)为链转移剂, 通过可逆加成-断裂链转移(RAFT)聚合制备了聚丙烯酰胺多面体低聚倍半硅氧烷(PAMPOSS)均聚物及其与甲基丙烯酸甲酯(PMMA)的嵌段共聚物(PAMPOSS-b-PMMA). 对产物结构组成和分子量及其分布进行表征. 结果表明, 在TTBT的控制下, POSS的均聚物和嵌段共聚物具有高分子量及窄分子量分布. 含POSS单体在超临界CO₂中为均相聚合, POSS聚合物的结晶性在一定程度上影响其在超临界CO₂中溶解性.     

本体共聚合制备丙烯/1-丁烯合金及表征

以球形高效负载的TiCl₄/MgCl₂/邻苯二甲酸二异丁酯(DIBP)为催化剂, 采用本体聚合方法进行丙烯与1-丁烯共聚合研究. 考察了共单体效应对共聚活性及聚合物立构规整性的影响; 表征了共聚物的结构. 结果表明, 随着1-丁烯/丙烯投料比的增加, 聚合活性呈先升高后降低的趋势, 在1-丁烯/丙烯摩尔投料比为0.26条件下聚合活性达到最高, 并随着共聚物中1-丁烯含量的增加, 共聚物的熔点明显下降, 分子量降低, 分子量分布变窄, 同时共聚物力学性能有明显提高, 透明度逐渐增加.     

TiCl4/XROH/MgCl2/Et3Al催化剂合成宽分子量分布乙烯/1-己烯共聚物

采用MgCl₂负载TiCl₄及1,3-二氯-2-丙醇给电子体(XROH),与三乙基铝助催化剂组成的催化剂体系,合成了1-己烯共聚率高且宽分子量分布的乙烯/1-己烯共聚物。 讨论了催化体系的组成、配比和聚合条件对乙烯/1-己烯共聚合行为,共聚物结构、分子量及分子量分布的影响。 结果表明,n(Ti)∶n(Mg)=10∶1,n(XROH)∶n(MgCl₂)=2.6∶1,n(Al)∶n(Ti)=100∶1,乙烯压力0.45 MPa,聚合温度80 ℃,聚合时间2 h,共聚单体(1-hexene)浓度0.25 mol/L时,催化效率达23.2 kg/g cat。 采用¹³C NMR、X-ray、SEM、WAXD、DSC、GPC等测试技术对催化剂、共聚物的结构进行了表征。 结果表明,在Zieglar-Natta(Z-N)催化体系中,给电子体多卤代醇与TiCl4结合,载体MgCl2的晶体结构发生了变化。 结晶度降低,有利于催化剂负载量的提高(ω(Ti)=4.8%)和催化效率增大。 催化体系产生了多种活性中心,使聚烯烃分子量分布变宽(15~20)。 多卤代醇还可增强1-己烯与乙烯的共聚能力,在共聚物中1-己烯的摩尔分数达5.1%。     

新型高效催化剂乙烯/1-丁烯气相齐聚和共聚制备弹性体及其结构与性能关系

用新型催化体系TiCl₄,Ti(OBu)₄/MgCl₂,SiO₂和ZnCl₂/醇/AlR₃催化乙烯与1-丁烯气相均聚及共聚,制得两种共聚物弹性体,发现新型催化剂体系具有独特的齐聚和原位共聚性能.采用¹³CNMR测定了共聚物链序列分布结构,观察到共聚单体在聚合物链中分布不均匀,存在较长的乙烯链段和较多的1-丁烯嵌段.产物DSC谱图表现出复杂的结晶熔融行为,存在多种结晶形态,出现熔融肩峰及双峰,与通常制得的LLDPE的结晶熔融行为有很大差别;结晶度和密度较低,并具有弹性体性质.     

SalenAl(OiPr)催化CO2与氧化环己烯共聚及影响因素研究

以SalenAl(OiPr)为催化剂,分别加入各种路易斯碱作为共催化剂催化二氧化碳与氧化环己烯共聚,发现共聚催化效率与共催化剂的供电子能力有关.分别研究催化剂浓度、共催化剂的用量、反应时间、反应温度、CO2压力等各种因素对该共聚反应的影响,发现SalenAl(OiPr)浓度为2 g/L时,以等摩尔量的二甲氨基吡啶(DMAP)作为共催化剂,在4 MPa的CO2和80℃下反应32 h,可得到碳酸酯键含量>99%的共聚产物,其催化效率高达495 g/g,13C-NMR检测表明共聚物为无规立构聚合物,GPC测得分子量Mn为55900,分子量分布比较窄(PDI=1.32).DSC得到共聚物的玻璃化转变温度为136℃,热重分析(TGA)可以看出共聚物在350℃可完全分解,具有优良的热分解性.     

联苯胺与二苯胺共聚物的界面聚合及其表征

采用界面聚合法合成了聚联苯胺、聚二苯胺以及联苯二胺与二苯胺的共聚物。利用红外光谱(FT-IR)、紫外可见吸收光谱(UV-vis)、电子扫描显微镜(SEM)、X射线衍射(XRD)、循环伏安等手段初步探讨了单体配比对共聚物形貌、结构及性能的影响。结果表明:界面聚合法合成的聚联苯胺呈现微米级棒状分布,随着共聚物中二苯胺结构单元的增加,棒状结构消失,聚合物趋于颗粒状分布;共聚后聚合物的共轭程度下降,但其结晶性与电化学行为得到了一定的改善;当共聚物中联苯胺与二苯胺的单体摩尔比为1/2时,共聚物电化学行为最佳。     

含POSS侧基的非环二烯烃易位聚合及离子型杂化聚合物表征

基于七异丁基-胺丙基-多面体低聚倍半硅氧烷(POSS-NH₂)与溴丁烯或溴代十一烯反应, 一步法合成了含POSS侧基的两种杂化二烯烃. 以钌卡宾络合物为催化剂的非环二烯烃易位(ADMET)聚合, 短链二烯烃未能发生, 而长链二烯烃能顺利实现. 将杂化二烯烃转变为离子型杂化二烯烃, 其ADMET聚合活性较高, 随着反应时间延长, 聚合物分子量明显增大, 分子量分布变窄, 体现了逐步聚合的特征. 核磁共振分析揭示了聚合物的不饱和结构和聚合反应的变化过程. 主链不饱和的无定形聚合物, 经氢化作用转变为饱和的离子型杂化聚乙烯, POSS基团精确地连接在聚乙烯骨架的侧位上, 且POSS基团和聚乙烯骨架均表现出较强的结晶能力. 这种离子型杂化聚乙烯具有球形的单分子或聚集形态, 可直接构筑纳米尺度的聚合物材料.     

二醚型 Ziegler-Natta 催化剂催化丙烯与极性单体共聚

 以三乙基铝 (TEA) 为保护剂, 研究了 TiCl4/MgCl2/芴二醚/Al(C2H5)3 体系催化丙烯与十一烯醇或十一烯酸的共聚反应. 结果表明, 在极性单体存在下, 聚合反应活性随极性单体加入量的增加而降低, 但可保持丙烯均聚活性的一半以上, 反应活性衰减较小. 同时, 随着极性单体加入量的增加, 极性单体在共聚物中的含量增加. 与十一烯酸相比, 十一烯醇共聚具有更高的共聚活性和共单体含量. 随着共聚物中极性单体含量的增加, 聚合物的熔点和结晶温度都有所降低. 反应温度对丙烯和十一烯醇共聚的反应活性和共单体含量影响较小.     

pH响应性含氟三嵌段共聚物的制备及性质研究

以苄醇(BzOH)与氢化钾(KH)反应形成的氧阴离子作为引发剂, 依次引发甲基丙烯酸-2-(N,N-二甲氨基)乙酯(DMAEMA, 简称DMA)、甲基丙烯酸-2-(N,N-二乙氨基)乙酯(DEAEMA, 简称DEA)和甲基丙烯酸-(2,2,3,3,4,4,5,5-八氟)戊酯(OFPMA)进行氧阴离子聚合, 获得含氟三嵌段共聚物PDMA-b-PDEA-b-POFPMA和PDEA-b-PDMA-b-POFPMA. 共聚物的化学结构可以通过不同单体的加料顺序和各种单体的投料量加以控制. 通过¹H NMR, ¹⁹F NMR和GPC测试, 研究聚合物的结构、分子量及分子量分布. 利用表面张力、荧光探针法、Zeta电位和透射电镜等测试方法, 研究共聚物在不同pH值的水溶液中的聚集行为.     

Organic–inorganic copolymers with double‐decker silsesquioxane in the main chains by polymerization via click chemistry

A series of novel organic–inorganic copolymers with polyhedral oligomeric silsesquioxane (POSS) in the main chains were synthesized via the copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition polymerization approach. Toward this end, we synthesized 3,13‐azidopropyloctaphenyl double‐decked silsesquioxane (DDSQ). This difunctional POSS macromer was used to copolymerize with α,ω‐dialkynyl‐terminated oligoethylenes with variable number of ethylene units. The organic–inorganic copolymers were obtained with the mass fraction of POSS up to 79%. Gel permeation chromatography showed that the high‐molecular‐weight copolymers were successfully obtained in all the cases. Differential scanning calorimetry showed that the amplitude of glass transitions for these copolymers was very feeble, suggesting that the segmental motions responsible for the glass transitions was highly restricted with DDSQ cages in the main chains. Thermogravimetric analysis showed that the organic–inorganic hybrid copolymers displayed extremely high thermal stability. Contact angle measurements showed that these organic–inorganic copolymers are highly hydrophobic and possessed very low surface energy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4221–4232     

Preparation and properties of propylene/POSS copolymer with rac-Et(Ind)2ZrCl2 catalyst

An organic-inorganic hybrid copolymer was prepared by using a C₂ symmetric ansa-metallocene catalyst in conjunction with modified methylaluminoxane (MMAO). Two kinds of monovinyl substituted polyhedral oligomeric silsesquioxane (POSS) monomers were used to copolymerize with propylene. A special experiment was carried out in order to confirm the purification of the copolymerization products. The unreacted monomer was completely removed by washing with an n-hexane/ethanol mixture. Thermal properties of the propylene/POSS copolymers exhibited improved thermal stability with higher degradation temperature and char yields, demonstrating that the inclusion of inorganic POSS nanoparticles made the organic polymer matrix more thermally robust.     

Synthesis and self‐assembly of tadpole‐shaped organic/inorganic hybrid poly(N‐isopropylacrylamide) containing polyhedral oligomeric silsesquioxane via RAFT polymerization

Aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) was used to prepare a POSS‐containing reversible addition‐fragmentation transfer (RAFT) agent. The POSS‐containing RAFT agent was used in the RAFT polymerization of N‐isopropylacrylamide (NIPAM) to produce tadpole‐shaped organic/inorganic hybrid Poly(N‐isopropylacrylamide) (PNIPAM). The results show that the POSS‐containing RAFT agent was an effective chain transfer agent in the RAFT polymerization of NIPAM, and the polymerization kinetics were found to be pseudo‐first‐order behavior. The thermal properties of the organic/inorganic hybrid PNIPAM were also characterized by differential scanning calorimetry. The glass transition temperature (T_g) of the tadpole‐shaped inorganic/organic hybrid PNIPAM was enhanced by POSS molecule. The self‐assembly behavior of the tadpole‐shaped inorganic/organic hybrid PNIPAM was investigated by atomic force microscopy and dynamic light scattering. The results show the core‐shell nanostructured micelles with a uniform diameter. The diameter of the micelle increases with the molecular weight of the hybrid PNIPAM. Surprisingly, the micelle of the tadpole‐shaped inorganic/organic hybrid PNIPAM with low molecular weight has a much bigger and more compact core than that with high molecular weight. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7049–7061, 2008     

Organic–inorganic hybrid diblock copolymer composed of poly (ε‐caprolactone) and poly(MA POSS): Synthesis and its nanocomposites with epoxy resin

Organic–inorganic hybrid diblock copolymers composed of poly(ε‐caprolactone) and poly(MA POSS) [PCL‐b‐P(MA POSS)] were synthesized via reversible addition‐fragmentation chain transfer polymerization of 3‐methacryloxypropylheptaphenyl polyhedral oligomeric silsesquioxane (MA POSS) with dithiobenzoate‐terminated poly(ε‐caprolactone) as the macromolecular chain transfer agent. The dithiobenzoate‐terminated poly(ε‐caprolactone) (PCL‐CTA) was synthesized via the atom transfer radical reaction of 2‐bromopropionyl‐terminated PCL with bis(thiobenzoyl)disulfide in the presence of the complex of copper (I) bromide with N,N,N′,N″,N″‐pentamethyldiethylenetriamine. The results of molecular weights and polydispersity indicate that the polymerizations were in a controlled fashion. The organic–inorganic diblock copolymer was incorporated into epoxy to afford the organic–inorganic nanocomposites. The nanostructures of the organic–inorganic composites were investigated by means of transmission electron microscopy and dynamic mechanical thermal analysis. Thermogravimetric analysis shows that the organic–inorganic nanocomposites displayed the increased yields of degradation residues compared to the control epoxy. In the organic–inorganic nanocomposites, the inorganic block [viz., P(MA POSS)] had a tendency to enrich at the surface of the materials and the dewettability of surface for the organic–inorganic nanocomposites were improved in terms of the measurement of surface contact angles. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Nanocomposites through copolymerization of a polyhedral oligomeric silsesquioxane and methyl methacrylate

The mechanical properties and thermal stability of polymers can be enhanced through the formation of nanocomposites. Nanocomposites consisting of hybrid copolymers of methacrylcyclohexyl polyhedral oligomeric silsesquioxane (POSS‐1) and methyl methacrylate (MMA) with up to 92 wt % (51 mol %) POSS‐1 and with superior thermal properties were synthesized using solution polymerization. The POSS‐1 contents of the copolymers were similar to or slightly higher than those in the feeds, the polydispersity indices were relatively low, and the degree of polymerization decreased with increasing POSS‐1 content. POSS‐1 enhanced the thermal stability, increasing the degradation temperature, reducing the mass loss, and preventing PMMA‐like degradation from propagating along the chain. The mass loss was reduced in a high POSS‐1 content copolymer since the polymerization of POSS‐1 with itself reduced sublimation. Exposure to 450 °C produced cyclohexyl‐POSS‐like remnants in the POSS‐1 monomer and in all the copolymers. The degradation of these remnants, for the copolymers and for the POSS‐1 monomer, yielded 75% SiO₂ and an oxidized carbonaceous residue. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4264–4275, 2007     

Characterization of PBT/POSS nanocomposites prepared by in situ polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS

Novel poly(butylene terephthalate) (PBT)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized by ring‐opening polymerization of cyclic poly(butylene terephthalate) initiated by functionalized POSS with various feed ratios. The impact of POSS incorporation on melting and crystallization behaviors of PBT/POSS nanocomposites was investigated by means of X‐ray diffraction and differential scanning calorimetry. It was found that the novel organic–inorganic association result in the significant alterations in the melting and crystallization behavior of PBT. Thermal studies confirmed that the incorporation of POSS can enhance the thermal stability of the polymers, and the copolymer glass transition temperature increased with the increasing of POSS macromonomer content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1853–1859, 2010     

Organic/inorganic hybrid star-shaped block copolymers of poly(l-lactide) and poly(N-isopropylacrylamide) with a polyhedral oligomeric silsesquioxane core: Synthesis and self-assembly

The star-shaped organic/inorganic hybrid poly(l-lactide) (PLLA) based on polyhedral oligomeric silsesquioxane (POSS) was prepared using octa(3-hydroxypropyl) polyhedral oligomeric silsesquioxane as initiator via ring-opening polymerization (ROP) of l-lactide (LLA). The molecular weight of POSS-containing star-shaped hybrid PLLA (POSSPLLA) can be well controlled by the feed ratio of LLA to initiator. The POSSPLLA was further functionalized into the macromolecular reversible addition-fragmentation transfer (RAFT) agent for the polymerization of N-isopropylacrylamide (NIPAM), leading to the POSS-containing star-shaped organic/inorganic hybrid amphiphilic block copolymers, poly(l-lactide)–block–poly(N-isopropylacrylamide) (POSS(PLLA–b–PNIPAM)). The self-assembly behavior of POSS(PLLA–b–PNIPAM) block copolymers in aqueous solution was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). DLS showed the PNIPAM block in the aggregates is temperature-responsive and its phase-transition is reversible. TEM proved that the star-shaped POSS(PLLA–b–PNIPAM) amphiphilic block copolymers can self-assemble into the vesicles in aqueous solution. The vesicular wall and coronas are composed of the hydrophobic POSS core and PLLA, and hydrophilic PNIPAM blocks, respectively. Therefore, POSSPLLA and POSS(PLLA–b–PNIPAM) block copolymers, as a class of novel organic–inorganic hybrid materials with the advantageous properties, can be potentially used in biological and medical fields.     

Synthesis,characterization, and temperature‐responsive behaviors of novel hybrid amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane

Organic/inorganic hybrid amphiphilic block copolymer poly(methacrylate isobutyl POSS)‐b‐poly(N‐isopropylacrylamide‐co‐oligo(ethylene glycol) methyl ether methacrylate) (PMAPOSS‐b‐P(NIPAM‐co‐OEGMA)) was synthesized via reversible addition–fragmentation chain transfer polymerization. The self‐assembly behavior of this block copolymer in aqueous solution was investigated by dynamic light scattering (DLS) and transmission electron microscopy. The results indicate that the novel block copolymer can self‐assemble into spherical micelles with PMAPOSS segment as the hydrophobic part and P(NIPAM‐co‐OEGMA) segment as the hydrophilic part. The temperature‐responsive characteristics of the assemblies were tested by UV–Vis spectra and DLS. Some factors such as the concentration, molecular weight, and copolymer generation that may affect the cloud point were studied systematically. The results reveal that this copolymer exhibits a sharp and intensive lower critical solution temperature (LCST). The essentially predetermined LCST can be conveniently achieved by adjusting the content of NIPAM or OEGMA domain. In addition, these novel hybrid micelles can undergo an association/disassociation cycle with the heating and cooling of solution and the degree of reversibility displaying a tremendous concentration dependence, as a novel organic/inorganic hybrid material with distinctive virtues can be potentially used in biological and medical fields, especially in drug nanocarriers for targeted therapy. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of raspberry-like monodisperse magnetic hollow hybrid nanospheres by coating polystyrene template with Fe(3)O(4)@SiO(2) particles

A new inorganic/organic hybrid material containing silsesquioxane was prepared by the reaction of caged octa (aminopropyl silsesquioxane) (POSS-NH(2)) with n-butyl glycidyl ether (nBGE) and 1,4-butanediol diglycidyl ether (BDGE). The copolymers of POSS, nBGE, and BDGE could be obtained with varied feed ratio of POSS-NH(2), nBGE, and BDGE in the preparation. The hybrid material was added into an epoxy resin (E51) for enhancing the toughening and thermal properties of the epoxy resin. The results showed that the toughening and the thermal properties of the cured epoxy resin were greatly improved by the addition of the hybrid. The enhancement was ascribed to nano-scale effect of the POSS structure and the formation of anchor structure in the cured network. The investigation of kinetics for the curing process of the hybrid-modified epoxy resin revealed that two kinds of curing reactions occurred in different temperature ranges. They were attributed to the reactions between amino groups of the curing agent with epoxy groups of E51 and with residue epoxy groups in the hybrid. The reacting activation energies were calculated based on Kissinger's and Flynn-Wall-Ozawa's methods, respectively.     

官能团化POSS及多臂星形聚酯的合成与表征

利用八乙烯基多面体齐聚倍半硅氧烷(OVPOSS)与2-巯基乙醇、1-巯基甘油或半胱胺盐酸盐发生高效的"巯基-烯"点击化学反应,制备了表面分别含有8个或16个羟基以及8个氨基的3种POSS衍生物POSS-8OH、POSS-16OH和POSS-8NH2,采用核磁共振波谱(1H-, 13C-NMR)和傅里叶变换红外光谱(FTIR)详细表征了它们的化学结构.随后,利用POSS-8OH和POSS-16OH中的羟基分别引发ε-己内酯(ε-CL)和2-乙氧基-2-氧代-1,3,2-二氧磷杂环戊烷(EOP)进行开环聚合,成功合成了疏水性八臂和十六臂星形聚己内酯(POSS-8PCL和POSS-16PCL)以及亲水性八臂星形聚磷酸酯(POSS-8PEEP).利用FTIR、1H-NMR、13CNMR、凝胶渗透色谱(GPC)和热失重分析(TGA)表征了星形聚酯的化学结构、分子量和分子量分布以及热稳定性.