原子转移自由基聚合研究进展

综述了原子转移自由基聚合的研究进展。     

活性自由基聚合的新进展--原子转移自由基聚合

活性自由基聚合是目前高分子科学中最为活跃的研究领域之一,原子转移自由基聚合(ATRP)反应是实现活性聚合的一种颇为有效的途径．也是高分子化学领域的最新研究进展之一。ATRP的独特之处在于使用了卤代烷作引发剂,并用过渡金属催化剂或退化转移的方式,有效地抑制了自由基双基终止的反应。ATRP可以同时适用于非极性和极性单体,可以制备多种结构形式的、结构清晰的高分子化合物。可实现众多单体的活性／可控自由基聚合。介绍了ATRP的研究进展,包括ATRP反应的特点、聚合反应机理、应用、研究现状及前景展望。     

甲基丙烯酸甲酯和苯乙烯在离子液体中的自由基聚合

甲基丙烯酸甲酯和苯乙烯经4,4’-偶氮-双(4-氰基戊酸)引发,分别在离子液体([C4mim][PF6])和苯中进行了自由基聚合反应,比较了相同引发剂和单体投料比下,2种介质体系中的聚合速率、相对分子质量和分子量分布,得出2种单体在[C4mim][PF6]中的聚合速率、相对分子质量明显高于苯中的产物,且[C4mim][PF6]经多次重复使用,均能得到性能稳定的聚合产物。     

ATRP合成线性苯乙烯-丙烯腈共聚物

以α-溴代异丁酸叔丁酯(t-BBiB)为引发剂,CuBr/2,2′-联二吡啶(Bpy)为催化体系,在70℃下经原子转移自由基聚合(ATRP)反应进行苯乙烯(St)和丙烯腈(AN)共聚合合成苯乙烯/丙烯腈共聚物。采用GC、~1H NMR和GPC对聚合反应过程和聚合产物进行了分析和表征。结果表明:单体浓度的半对数曲线与聚合时间呈线性关系,聚合物摩尔质量随单体转化率的上升而线性增加,而且摩尔质量分布在1.2～1.3之间,表现出活性聚合反应特征。随着聚合反应的进行,共聚物组成趋向于原始单体组成,大分子链存在梯度结构。     

Radical Polymerization of Methyl Methacrylate in Presence of Ferrocene. Monte Carlo Simulation

Abstract

Monte-Carlo technique is used for the numerical simulation of radical polymerization kinetics of methyl methacrylate in the presence or absence of ferrocene and exposition of molecular-weight distribution during the process. The peculiarities of polymeric radical concentration changes at the initial stage of polymerization are shown. Satisfactory correspondence between calculated and experimental data is obtained. The data of numerical experiment have allowed to evaluate the influence of ferrocene on kinetic parameters of polymerization.     

原子转移自由基聚合在树形聚合物合成中的应用

原子转移自由基聚合(ATRP)技术是一种新型的可控/活性聚合技术,可有效地对聚合物的分子结构进行设计,制备出各种不同性能、不同组成、不同功能化的结构确定的聚合物。综述了利用ATRP技术合成树枝状-线性嵌段共聚物、类树枝状聚合物(dendrimer-like polymer)、具有刺激-响应性末端基团的树枝状聚合物、树枝状-星型嵌段共聚物和基于树枝状聚合物的聚合物刷的研究进展。     

Molecular and Free Radical Products of Reactions of Nitrogen Dioxide with Polyvinylpyrrolidone

Abstract

The mechanism of reactions of nitrogen dioxide with polyvinylpyrrolidone at 295–363 K has been considered. The nature of the molecular and free radical products of reactions has been studied by UV and ESR spectroscopy. The main molecular products are nitrites and nitrozoamides. The formation of stable acylalkylnitroxyl and iminoxyl radicals was registered. The influence of the structural-physical modification of the polymer at filling by aerosil has been established on kinetics of the formation of radicals.     

Synthesis and Properties of Electroactive Polyaniline-Graft Polymethyl Methacrylate Copolymer by Atom Transfer Radical Polymerization

In this research, N-substituted polyaniline was synthesized by chlorine-terminated chloroacetyl chloride incorporation and methylmethacrylate polymerization done onto the leucoemeraldine. The authors prepared polyaniline-graft-polymethylmethacrylate copolymer by methylmethacrylate ATRP using polyaniline macroinitiator. First, polyaniline was prepared by chemical oxidation. The macroinitiator was synthesized via reaction of leucoemeraldine's nitrogen with chloroacetyl chloride. Macroinitiator and graft copolymer were characterized by FT-IR and ¹H-NMR. SEM and AFM images showed the growing of poly methylmethacrylate chains on polyaniline backbone. Solubility test revealed that polyaniline-graft-poly(methylmethacrylate) was in some organic solvents. CV study confirmed this copolymer was electroactive. Elemental analysis determined the amount of grafting polymethylmethacrylate on leucoemeraldine.     

BrO与ClO反应机理的理论研究

利用密度泛函理论对BrO自由基与ClO反应机理进行了深入探讨,在B3LYP/6-31G（3df）水平上对该反应体系的反应物、中间体、过渡态以及产物进行几何构型优化,对反应通道进行了IRC（内禀坐标）路径解析,分析了沿各反应通道的能垒,讨论了反应过程中化学键的断裂、生成以及键的变化规律,比较得出主要产物是Br自由基与OClO。     

The Effect of Initiators and Reaction Conditions on the Polymer Syntheses by Atom Transfer Radical Polymerization

The controlled/“living” radical polymerization of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and styrene by atom transfer radical polymerization (ATRP) is reported. The effect of initiators and reaction conditions on the ATRP results was investigated. Controlled polymerizations with predictable molecular weights were performed on MMA at 40^○C and 80^○C using a CuCl/bipyridine (bipy) catalyst system in conjunction with 1-bromoethyl benzene as the initiator. The addition of a polar solvent was necessary to decrease the polymerization rate and afford low polydispersity materials. The ATRP processes followed a first-order kinetics with respect to the monomer concentration. The molecular weights of the resulting polymers were very close to their calculated values and increased with the conversion. The ATRP results of styrene showed a similar trend and revealed that CuBr/bipy or CuBr/PMDETA was a more suitable catalyst system than CuCl/bipy. In addition, it was found that controlled polymerizations could be readily carried out both in a nonpolar solvent or in bulk. Furthermore, by using the bromine-terminated polymer as the macroinitiator, diblock copolymers of PSt-b-PMMA, PSt-b-PHEMA, PMMA-b-PSt, and PMMA-b-PHEMA could be obtained. Thermal analysis and X-ray diffraction studies confirmed the amorphous structures of the resulting polymers.     

An alternative pathway for the hydrolysis of epoxy ester compounds

The water-soluble polymer, poly(2,3-dihydroxypropyl methacrylate), also known as poly(glyceryl methacrylate), is known to isomerize and give a mixture of 2,3- and 1,3-isomers in both the monomeric and polymeric forms. The glyceryl methacrylate monomer was synthesized via acid-catalyzed hydrolysis of glycidyl methacrylate, which produced a mixture of 1,3- and 2,3-isomers in a ratio of 25% and 75%, respectively. This was surprising, as hydrolysis of epoxy compounds generally yields a 1,2-diol product. Furthermore, the level of 1,3-isomer at equilibrium is known to be 10% in both the glyceryl methacrylate monomer and polymer. An alternative hydrolysis pathway involving the ester and epoxy moieties was investigated for glycidyl methacrylate, and a mechanism was proposed.     

超声波作用下反应体系组成对苯乙烯分散聚合反应规律的影响

研究了超声波作用下反应体系组成对苯乙烯(St)分散聚合反应规律的影响,表明超声波作用下的分散聚合反应并非一般的热引发分散聚合反应,超声波的空化作用可有效地、多途径地生成更多的自由基。掌握了聚合反应规律,可初步实现根据聚苯乙烯(PS)粒径及分布和聚合反应速率要求进行反应体系的配方设计。     

3，3＇-二氨基二苯砜的合成研究

依据芳香族硝基化合物在酸性条件下发生还原反应的原理。利用自制溶剂的溶解性和催化性,成功制取了3,3’-二氨基二苯砜粗品,精制之后,能够达到市场工业品级别。并简要介绍了3,3’-二氨基二苯砜的其它两种制法。     

保留盆腔植物神经直肠癌根治术对术后性功能和排尿功能的影响

目的探讨直肠癌根治术中保留盆腔植物神经对男性术后性功能和排尿的影响。方法依据进展程度,对470例行直肠癌根治术的患者进行回顾性分析,其中完全保留神经者366例,保留一侧或部分神经者43例,非保留神经者61例。结果完全保留神经者近期排尿障碍率1.64%,远期排尿障碍率为0。保留一侧或部分神经者近期排尿障碍率11.62%,远期排尿障碍率2.33%。非神经保留者近期排尿障碍率19.67%,远期排尿障碍率6.56%。完全保留神经者术后勃起功能障碍发生率1.09%,射精功能障碍率3.28%。保留一侧或部分神经者勃起功能障碍率16.27%,射精功能障碍率37.21%。非神经保留者勃起功能障碍率39.34%,射精功能障碍率50.82%。结论保留植物神经的直肠癌根治术,可保存患者术后的性功能和排尿功能,提高患者术后生活质量。     

基于RAFT过程的丙烯酸可控自由基聚合

以2-{[(十二烷基硫基)硫代甲酰基]硫烷基}琥珀酸(DCTSS)为链转移剂(CTA)在水溶液中调控丙烯酸(AA)进行可逆加成-断裂链转移自由基聚合(RAFT)。考察了引发剂种类、聚合温度、n(引发剂)/n(CTA)、n(AA)/n(CTA)、时间对丙烯酸聚合的影响。结果表明,以4,4′-偶氮二(4-氰基戊酸)(V501)为引发剂,聚合反应具有活性可控聚合的特征,聚合动力学呈线性关系,聚合物的黏均相对分子质量(以下简称黏均分子量)随转化率的增加而线性增加,得到分子量可控、分布为1.50左右的聚合物;升高温度可以加快反应速率,使黏均分子量分布降低,反应更加可控;降低n(V501)/n(CTA)值可以使聚合产物的黏均分子量升高,但聚合速率也会降低;随着n(AA)/n(CTA)值的增加,聚合产物的黏均分子量也增加,并且基本呈线性关系;最佳反应时间为2h;用所得聚合物作为大分子RAFT试剂,丙烯酸正丁酯(BA)为单体进行扩链反应,得到聚丙烯酸-b-聚丙烯酸正丁酯;用核磁共振氢谱、傅立叶变换红外光谱对产物结构进行了表征。     

活性自由基聚合法合成偶氮聚合物研究进展

偶氮聚合物具有光致顺反异构和光学各向异性,其在光电信息技术领域具有重要的潜在应用前景.利用活性自由基聚合的方法可以在温和的条件下合成得到特定结构与预定相对分子质量的偶氮聚合物.综述了该技术领域的最新研究进展,并对近年来出现的聚合体系与方法,包括氮氧稳定自由基聚合(NMP)、原子转移自由基聚合(ATRP)、可逆加成一断裂链转移(RAFT)聚合等,作了简要的评述.     

阻聚剂TBC对亚硫酸盐自动氧化的阻滞作用

通过除氧试验和空气氧化试验,研究了阻聚剂ＴＢＣ对亚硫酸盐自动氧化的阻滞作用。结果表明,自由基链反应引发剂铜离子能够加速亚硫酸盐与氧的反应,自由基吸收剂阻聚剂ＴＢＣ能够通过消除亚硫酸盐氧化过程中生成的自由基而抑制反应,水的ｐＨ值、碱度和硬度成分则无影响。试验结果为亚硫酸盐氧化的自由基机理提供了有力的证据,也为亚硫酸盐的贮存失效提供了有效的防止方法     

分光光度法测定羟自由基的捕捉剂比较研究

研究了不同羟自由基捕捉剂的分光光度法,探讨了测定羟自由基的可靠、准确方法。利用具有清除·OH作用的抗坏血酸和谷胱甘肽,考察邻二氮菲、水杨酸、结晶紫、亚甲蓝作为·OH捕捉剂,用分光光度法测定·ON的可行性和可靠性。实验结果认为不确定的原因影响邻二氮菲和水杨酸法的测定结果,亚甲蓝法不可行,结晶紫测定结果合理,方法可行。在4种捕捉剂中,只有结晶紫测定·OH方法可靠,稳定性好,精密度高,可以用于测定羟自由基。     

CH3SH与CN自由基反应的理论研究

在MP2／6—311G（d,p）水平上研究了CH3SH与CN自由基反应的机理,优化了所有驻点的几何构型,并进行了振动频率分析。用双水平方法G3MP2／／MP2／6—311G（d,p）构建了反应势能面。用RRKM理论计算了200-1000K温度范围内的速率常数,计算值与实验值符合较好。结果表明：CN自由基中的C抽取一SH上的H是主要反应通道,CH。S和HCN是主要反应产物。     

离子交换树脂催化合成二苯甲烷二氨基甲酸酯的研究

二苯甲烷二氨基甲酸酯是非光气合成二苯甲烷二异氰酸酯(MDI)的重要中间体。以离子交换树脂为催化剂,对苯氨基甲酸甲酯与甲醛缩合反应制备二氨基甲酸酯进行了研究,考察了催化剂、反应温度、原料配比、催化剂用量和反应时间对反应的影响。优惠条件:温度100℃,原料配比n(对苯氨基甲酸甲酯)∶n(甲醛)=6∶1,催化剂用量为苯氨基甲酸甲酯质量的10%,反应时间4h。此条件下,二氨基甲酸酯收率为57%,选择性为60%。