紫外光引发硅氢加成反应制备超支化聚碳硅氮烷

在二乙酰丙酮铂存在下, 以紫外光引发AB4型单体双(N,N-二烯丙基胺基)甲基硅烷发生硅氢加成反应, 制备了超支化聚碳硅氮烷. 聚合产物通过FTIR, 1H NMR, 13C NMR和29Si NMR谱和体积排除色谱/激光光散射联用技术进行表征. 与常规加热条件下Karstedt's催化剂催化的硅氢加成聚合相比, 光引发聚合的反应速度快. 波谱分析表明, 聚合过程中以α位硅氢加成反应为主. 光引发聚合制备的超支化聚碳硅氮烷支化度(DB)和平均支化数(ANB)分别为0.46和0.53, 与理论值相近. 其重均分子量为12500 g/mol, 分子量分布系数为2.1, Mark-Houwink方程指数α为0.44, 与热聚合制备的超支化聚碳硅氮烷的参数相近.     

三甲基硅化合物复合体系引发1,3-戊二烯阳离子聚合研究

研究了三甲基硅化合物 ,主要是三甲基硅酯和三甲基硅氯化物 (TMSCI)与路易斯酸所形成的复合引发体系引发聚合 ,1,3 戊二烯 (PD)的聚合反应行为 ,考察了引发体系引发PD聚合所得聚合物的产率 ,分子量及分子量分布 ,聚合反应速率和聚合反应机理等 ;研究了多种给电体———醚、酮对聚合反应的影响     

含环三硅氮烷的星形聚硅氧烷的合成——环硅氮阴离子引发环硅氧烷开环聚合

以环三硅氮锂盐（ＤＮＬｉ３）为引发剂，成功地引发了环硅氧烷开环聚合．通过含氮量测定，利用１Ｈ、２９ＳｉＮＭＲ和ＩＲ谱以及分子量测定（ＧＰＣ）和特性粘度测试，并与模型化合物进行比较，证明所得聚合物是含环三硅氮烷的星形聚硅氧烷．研究了六甲基环三硅氮锂盐引发八甲基环四硅氧烷（Ｄ４）开环聚合的动力学，结果表明该聚合反应相对于Ｄ４为一级反应，同时也比较了不同促进剂对聚合速率的影响，ＤＭＦ对聚合速率的促进作用比ｄｉｇｌｙｍｅ大     

三甲基硅化合物在阳离子引发中的应用

介绍了三甲基硅化合物在阳离子聚合引发反应中的应用，对两类三甲基硅化合物（三甲基硅酯和三甲基硅卤化物）及其阳离子引发体系方面的研究进展分别作了详细阐述。     

硅氮负离子引发六甲基环三硅氧烷开环聚合的动力学研究

以二甲基亚砜(DMSO)或四氢呋喃(THF)作为促进剂,六苯基环三硅氮烷三锂盐(P3NLi)可以引发六甲基环三硅氧烷(D3)进行开环聚合,通过29Si-NMR谱的硅峰面积比例确定了不同反应时间D3的转化率,经过计算得到聚合反应对THF、DMSO、D3、P3NLi的反应级数,并给出了对应的动力学方程.     

用硅烯醚型引发剂进行的基团转移聚合

本文报道了一类硅烯醚型的基团转移聚合引发剂。并以负离子和HgI_2等为催化剂,进行了甲基丙烯酸酯和丙烯酸酯的基团转移聚合。得到了实测分子量和理论分子量相近且分散性较小的浆合物。进行了甲基丙烯酸甲酯的活性聚合以及其与丙烯酸酯的A-B-A型三嵌段共聚,证实具有活性高分子的特征。探讨了该类引发剂引发基团转移聚合的机理,研究了催化剂和引发剂的配合选择性以及催化剂和引发剂的摩尔比对产物分子量和转化率的影响,发现该类引发剂引发的基团转移聚合是一恒速聚合反应。     

硅表面分子刷图案化及生长DNA纳米管

结合"自上而下"和"自下而上"技术构建微纳米器件是目前纳米科学和技术领域追逐的目标之一。本文首先采用硅氢化反应在硅表面共价偶联引发聚合的活性基团,接着实施表面原子转移自由基聚合(ATRP)反应形成高分子刷poly(PEGMA),采用"自上而下"的光刻技术在硅表面制备功能化的图案,最后利用"自下而上"的DNA自组装技术在图案部分原位生长DNA纳米管。上述组装过程通过多次透射反射红外光谱、凝胶电泳、透射电镜和扫描电镜进行了检测,证实了硅芯片表面定位生长DNA纳米管的可行性。     

超支化聚硅碳烷-g-环糊精聚合物刷的合成与表征

通过硅氢加成反应和核多步法聚合合成出超支化聚硅碳烷(HBP),并对其端基进行了硅氢化、羟基化和酰氯化三步改性得到大分子引发剂HBP-Cl;再用其引发甲基丙烯酸N,N-二甲氨基乙酯(DMA)进行原子转移自由基聚合(ATRP),得到超支化聚硅碳烷-g-聚甲基丙烯酸N,N-二甲氨基乙酯(HBP-g-PDMA),最后将单-6-碘代β-CD通过离子键固载到PDMA链上,得到超支化聚硅碳烷-g-环糊精聚合物刷(HBP-g-PDMA-β-CD).采用FTIR、1H-NMR、13C-NMR、29Si-NMR对其结构进行了表征,利用凝胶渗透色谱/多角度激光光散射(SEC/MALLS)联用仪和激光粒度分析仪研究了其高分子的精细结构,并通过元素分析研究了固载时间对β-CD固载量的影响.     

硅氢化聚合的研究进展

硅氢化反应可以构建Si—C、Si—O、Si—N键,是有机硅化学中的重要反应,通过研究筛选合适的催化体系设计适当的单体进行硅氢化聚合来构建新型的大分子进而制备新的高分子材料是现在高分子化学发展的重要方向之一。本文综述了近几十年硅氢化聚合的研究进展,根据硅氢化聚合单体官能团的种类与数目,分为烯烃的硅氢化聚合、炔烃的硅氢化聚合、醛酮的硅氢化聚合以及非线性硅氢化聚合四个部分进行叙述,重点介绍不同结构的单体所得聚合物的分子量和性质的差异,通过对这方面的总结与分析,希望能够给予从事相关工作的科研工作者一定的思路和启发。     

基团转移聚合新引发剂——1-(N,N-二甲氨基)-1-三甲基硅氧基丁烯-1的合成与性质的研究

本文报道了一种新的基团转移聚合引发剂——1-(N,N-二甲氨基)-1-三甲基硅氧基丁烯-1,对由其引发的GTP、其引发活性、与催化剂及单体用量比对聚合速度、分子量分布的影响进行了研究,得到了分散性较小的实测分子量和理论分子量相近的PMMA。     

Etude des copolymeres (ethylene-hexene-1) par resonance magnetique nucleaire du proton et du carbone 13

Ethylene 1-hexene copolymers obtained by catalytic polymerization have been examined by ¹H and ¹³C NMR. Copolymer compositions have been determined by ¹H NMR and i.r. and the sequence distributions for 1-hexene by ¹³C NMR. Variations of the copolymer microstructure have been related to the experimental conditions for copolymerization.     

聚合方法对一种正离子聚丙烯酰胺结构与性能的影响

对相同进料比下,以过硫酸胺/亚硫酸氢钠为氧化还原引发剂,分别用溶液法和反相微乳液法合成的丙烯酰胺(AM)与2-甲基丙烯酰氧乙基三甲基氯化胺(MADQUAT)的共聚物P(AM-MADQUAT),根据单体竞聚率计算了两种共聚物的序列分布和组成分布.考察了两种聚合物结构对高岭土絮体尺寸、zeta电位降以及絮体压缩屈服应力的影响,初步建立了不同聚合方法合成的阳离子聚丙烯酰胺结构与絮凝性能之间的相关性.     

Controlled phase separations in solutions of soluble polyelectrolyte complex of DIVEMA (copolymer of divinyl ether and maleic anhydride)

Copolymer of divinyl ether and maleic anhydride (DIVEMA) is known to possess some anti-tumor and immune-stimulating activity and use as a drug carrier in anti-tumor drug delivery systems. Samples of DIVEMA of different degrees of polymerization were synthesized and characterized. Interaction of the hydrolyzed water-soluble DIVEMA polyanions with poly(N-ethyl-4-vinylpyridinium) cations (PEVP) has been studied. According to the potentiometry data, almost all carboxylic groups of the polyanions were able to form ion pairs with PEVP. In aqueous and water-salt solutions, formation of either soluble or insoluble polyelectrolyte complexes occurred depending on pH, ratio of the oppositely charged groups, and degree of polymerization of PEVP and/or DIVEMA. The phase separations followed general rules revealed by studying mixtures of PEVP and polycarboxylic acids. However in the case of DIVEMA, a significant broadening of the region for insoluble complexes at the expense of the region of soluble complexes was established. The data obtained demonstrate plausible advantages of the complex formation as the non-covalent modification of the polymeric carrier that endow DIVEMA with the ability for reversible soluble-insoluble transformation, in particular at physiological pH and ionic strength.     

Effect of 1-Hexene Comonomer on Polyethylene Particle Growth and Kinetic Profiles

Summary: The polymer growth and the microstructure of the final polymer are greatly affected by mass transfer, especially in the early stages of polymerization. In the present work, the catalytic system (nBuCp)₂ZrCl₂/MAO immobilized over SiO₂-Al₂O₃ has been tested in ethylene-1-hexene copolymerizations using different amounts of comonomer. The catalytic activity shows a positive comonomer effect up to 1-hexene concentration of 0.724 mol/L since larger amounts of 1-hexene lead to a decrease in the activity. Copolymer properties analyzed by ¹³C NMR, GPC, CRYSTAF and DSC point to the presence of important amorphous regions in the growing polymer chains as the 1-hexene concentration increases. In order to study the incorporation of 1-hexene during ethylene polymerization, several experiments were performed with 0.194 mol/L of 1-hexene, 5 bar of ethylene pressure and different polymerization times. The incorporation of 1-hexene decreases slightly at polymerization times above 20 minutes. From cross-sectioned SEM images it can be concluded that the presence of 1-hexene helps catalyst fragmentation which could be related with the filter effect proposed by Fink.     

A new self-doped copolymer consisting of 3-methyl thiophene and aniline units

The copolymer films of sulfonated aniline and sulfonated 3-methyl thiophene were synthesized by electrochemical polymerization. The sulfonated copolymer films have better solubility in DMSO and KOH than the corresponding homopolymers. The conductivity of the copolymer films increase with the increase in the number of thiophene rings in the polymeric backbone. Copolymer films synthesized were investigated by cyclic voltammetry, UV-visible and FT-IR spectroscopy, dry conductivity and intrinsic viscosity measurements and elemental analysis. The elemental analysis and UV-visible spectroscopic results show that copolymer films have properties intermediate between the two homopolymers.     

无机-高分子磁性复合粒子的制备与表征

详细地研究了乳化剂用量对种子乳液聚合反应的影响,并成功地制备出粒径约300nm的苯乙烯/丙烯酸共聚小球。另外,还报道使用化学共沉淀法使无机粒子与高分子球复合,制备出高分子球为核,无机粒子为壳层的磁性复合粒子,使用XRD、TEM等手段对此复合粒子进行了表征。同时,进一步研究了这种复合粒子悬浮液的悬浮性能以及粘度随磁场的变化情况。     

Polymerization Kinetics and Microstructure of Ethylene/1‐Hexene Copolymers Made with Dual Metallocenes

Mathematical models are developed to describe the polymerization of ethylene and 1‐hexene with a constrained geometry catalyst (CGC‐Ti) and with bis(cyclopentadienyl)‐zirconium (IV) dichloride (Cp₂ZrCl₂). Particle swarm optimization is used to fit these models to homo‐ and copolymerization data. The models are also used to describe copolymerizations with mixtures of CGC‐Ti and Cp₂ZrCl₂ to make copolymers with inverse short chain branching distribution. Copolymer molecular weight and short chain branch distributions, as well as polymerization rates with the dual metallocene system, are measured to test whether they agreed with model predictions. The results show that the two metallocenes do not interact strongly when used as a mixture to make ethylene/1‐hexene copolymers.     

Copolymerization with depropagation: A study of α-methyl styrene/methyl methacrylate in solution at elevated temperatures

In free-radical polymerization, solvents are routinely used to reduce the solution viscosity and molecular weight. In the case of the α-methyl styrene/methyl methacrylate copolymer system, reducing the monomer concentration also has significant effects on the copolymer composition and maximum conversion obtained. Reactivity-ratio studies as well as full-conversion-range data were provided, and the results were compared to similar data in the bulk phase from our earlier work. A 30 wt % toluene solution was used for all experimental conditions. Copolymer composition modeling results were also presented. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1753–1763, 2001     

Ethylene/1-Hexene Copolymerization and Synthesis of LLDPE/Nanocarbon Composite through In Situ Polymerization

Copolymerization of ethylene/1-hexene using a modified ZN-type catalyst was carried out in the presence of triethylaluminium as cocatalyst. The optimum copolymerization activity was obtained at Al: Ti = 357: 1, 60°C and the comonomer concentration of 0.6 mol/L in the range studied. Copolymer/nanocarbon (including multiwalled carbon nanotube, graphene nanoplatelet) composites were prepared via in-situ polymerization. The copolymerization activity decreased by addition of the nanocarbon into the reactor. The presence of graphene nanoplatelet in nanocomposites reduced the melting temperature and increased heat of fusion, crystallinity and density of the obtained polymer. In the copolymer/carbon nanotube nanocomposites, decreasing of melting temperature was observed in comparison to pure copolymer, whereas, heat of fusion, crystallinity and density increased. The results of TGA analysis showed that the addition of nanocarbons has improved the thermal stability of obtained copolymers.     

Synthesis of a new hyperbranched,vinyl macromonomer through the use of click chemistry: Synthesis and characterization of copolymer hydrogels with PEG diacrylate

A new biodegradable, water‐soluble macromonomer based on the commercial hyperbranched polyester Boltorn^®H20 has been synthesized through the use of click chemistry. The macromonomer was developed with the aim of being injected with a comacromonomer, poly(ethylene glycol) (PEG) diacrylate, for in situ copolymerization to form biodegradable polymer hydrogels. Copolymer hydrogels were prepared from the macromonomer and PEG diacrylate (FW 700) by free radical copolymerization. A degree of phase separation of the hydrogels was observed during polymerization and with increasing incorporation of the Boltorn macromonomer an increasing tendency for the formation of macropores was observed. The swelling ratios of the gels in water and phosphate buffered saline solution, PBS, all increase with increasing Boltorn macromonomer concentration, as did the penetrant diffusion coefficients and the degradation rate in PBS. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012