梳型接枝共聚物的合成（IV）-氯乙酸降冰片烯甲酯引发苯乙烯、甲基丙烯酸甲酯原子转移自由基聚合的研究

首次报道以自制氯乙酸降冰片烯甲酯（NMCA）为引发剂的苯乙烯、甲基丙烯酸 甲酯的原子转移自由基（ATRP）本体聚合。详细考察了单体转化与反应时间、产物 分子量及分子量分布间的关系。研究发现，此引发引发甲基丙烯酸甲酯ATRP反应所 得聚合物的分子量分布较宽（PDI = 1.80～2.45)，且实测值（GPC）与理论值偏差 较大。而NMCA引发的苯乙烯的ATRP反应可得分子量分布较窄（PDI = 1.54)、实验 值（GPC）与理论值基本吻合的产物。单体转化率随反应时间的变化及产物分子量 随单体转化率变化研究证明这一聚合反应具有活性聚合反应特征。产物的NMR分析 证明所合成产物分子中降冰片烯环上双键未参与聚合反应。     

梳型接枝共聚物的合成（IV）-氯乙酸降冰片烯甲酯引发苯乙烯、甲基丙烯酸甲酯原子转移自由基聚合的研究

首次报道以自制氯乙酸降冰片烯甲酯（NMCA）为引发剂的苯乙烯、甲基丙烯酸 甲酯的原子转移自由基（ATRP）本体聚合。详细考察了单体转化与反应时间、产物 分子量及分子量分布间的关系。研究发现,此引发引发甲基丙烯酸甲酯ATRP反应所 得聚合物的分子量分布较宽（PDI = 1.80～2.45),且实测值（GPC）与理论值偏差 较大。而NMCA引发的苯乙烯的ATRP反应可得分子量分布较窄（PDI = 1.54)、实验 值（GPC）与理论值基本吻合的产物。单体转化率随反应时间的变化及产物分子量 随单体转化率变化研究证明这一聚合反应具有活性聚合反应特征。产物的NMR分析 证明所合成产物分子中降冰片烯环上双键未参与聚合反应。     

引发剂结构对原子转移自由基聚合反应的影响

研究了三种不同结构的引发剂,溴代乙酸乙酯（EBrA)、α-溴代丁乙酯（EBrB)、α－溴代异丁酸乙酸（EBriB)引发的苯乙烯的原子转移自由基聚合反应（ATRP）。发现EBrA引发的苯乙烯的ATRP不是“活性”聚合。EBriB引发的苯乙烯的ATRP引发效率不够高,也不是典型的“活性”聚合。EBrB引发的苯乙烯的ATRP是较为典型的“活性”聚合：聚合物的分子量可以通过调节单体／引发剂的投料量及反应时间来控制,所得聚合物的分子量分布很窄,且有随转化率的增加而逐渐变窄的趋势。     

γ-射线辐射活性自由基聚合研究

本文对γ- 射线辐射条件下的活性自由基聚合反应研究及进展进行了综述。虽然γ- 射线辐射引发聚合反应通常是不可控的,但在有机硫化物,如二硫代羧酸酯或三硫代碳酸酯存在下,则成功地实现了可控/活性自由基聚合。聚合过程中聚合物分子量随单体转化率线性增长,不但可控,且分布窄,也可以用于合成嵌段共聚物。有机硫化物对聚合反应控制起着关键性作用,硫化物的结构对于γ- 射线辐射活性自由基聚合行为的影响显著。γ- 射线辐射聚合的突出优点是可在室温或更低的温度下实施,且不需要加入引发剂。在环硫化合物存在下,获得了环形聚合物;而且使热和光敏感的叠氮类单体实现了活性聚合。     

甲基丙烯酸甲酯的原子转移自由基悬浮聚合

以 1 苯基氯乙烷为引发剂 ,氯化亚铜为催化剂 ,2 ,2 联吡啶为配体 ,外加搅拌 ,氮气保护下进行了甲基丙烯酸甲酯 (MMA)在 80℃下的原子转移悬浮聚合 .结果表明 ,聚合反应符合对单体浓度为一级的动力学关系 .经计算聚合体系的增长自由基浓度为 5 .74× 10 - 8mol L .聚合物分子量随转化率呈线性增加 ,分子量分布较窄 ,Mw Mn 在 1.37～ 1.40之间 .还以AIBN为引发剂 ,在三氯化铁和三苯基膦存在下进行了MMA的反向原子转移本体和悬浮聚合研究 .结果证明本体聚合具有好的可控特征 ,分子量随转化率呈线性增长 ,分子量分布指数在 1.2 7～ 1.31之间 .聚合反应速率较快 ,聚合体系中的增长自由基浓度较高 ,为 1.6 4× 10 - 7mol L .而在此催化体系下的悬浮聚合则完全失去了活性特征     

自由基活性聚合及其最新进展

本文介绍了实现自由基活性聚合的动力学、热力学条件及可能的途径。在这些条件下自由基保持稳定的低浓度，增长链自由基与休眠种处于动力学平衡动态，可有效地控制聚合反应，使聚合反应具有聚合物分子量随反应时间、单体转化率成线性增长关系及所得聚合物分子量分布较窄的特征，并且在加入第二单体时可继续生成嵌段共聚物。     

富马酸亚铁催化甲基丙烯酸甲酯活性自由基聚合的研究

以富马酸亚铁为催化剂,以2-溴代异丁酸乙酯为引发剂,在90℃下进行甲基丙烯酸甲酯的原子转移自由基本体聚合及溶液聚合.聚合物的数均相对分子质量随单体转化率的增加而线性增加,与时间呈良好线性关系,本体聚合时分子量分布 (PDI) 在1.5～1.7之间,溶液聚合时PDI＜1.5.通过聚合物扩链反应和端基分析,表明富马酸亚铁催化原子转移自由基聚合反应具有活性(可控)聚合的特征.     

富马酸亚铁催化甲基丙烯酸甲酯活性自由基聚合的研究

以畜马酸亚铁为催化剂,以2-溴代异丁酸乙酯为引发剂,在90℃下进行甲基丙烯酸甲酯的原子转移自由基本体聚合及溶液聚合.聚合物的数均相对分子质量随单体转化率的增加而线性增加,与时间呈良好线性关系,本体聚合时分子量分布(PDI)在1.5～1.7之间,溶液聚合时PDI＜1.5.通过聚合物扩链反应和端基分析,表明富马酸亚铁催化原子转移自由基聚合反应具有活性(可控)聚合的特征.     

含芳酰胺结构的新型甲壳型液晶高分子PMPACS的聚合反应动力学研究

采用称量法和GPC,研究了以二甲基乙酰胺为溶剂,偶氮二异丁腈为引发剂,自由基溶液聚合制备含芳酰胺结构的新型甲壳型液晶高分子聚[乙烯基对苯二甲酸二(4-甲氧基苯胺)](PMPACS)的聚合反应动力学.研究发现,(1)MPACS的聚合反应在60℃时主要为双基偶合终止,所以反应后期聚合物分子量明显增大,分子量分布变窄;(2)该反应的聚合反应速率方程为Rp=kp[M][I]1/2,表观活化能Eα=44 kJ/mol,在60℃时的聚合反应常数kp=1.04 L·mol-1·h-1;(3)相同聚合条件下,单体的转化率和数均分子量随单体初始浓度[M]0的增加而增大,当引发剂浓度[I]0增加时,聚合物的分子量随之降低,分子量分布增大;(4)该研究虽采用普通自由基聚合,所得聚合物的分子量分布却较窄,仅为1.1～1.4.     

SOCl2／SnCl4—DMSO／n—Bu4NCl引发体系苯乙烯活性阳离子聚合反应的研究

研究表明，ＳＯＣｌ２／ＳｎＣｌ４引发体系的苯乙烯聚合反应很快，但所得聚合产物的分子量分布宽（Ｍｗ／Ｍｎ＝４．３７），且其ＧＰＣ曲线呈多重峰；单独加入季铵盐（ｎ－Ｂｕ４ＮＣｌ）或二甲基亚砜（ＤＭＳＯ）可使聚合产物分子量分布明显变窄，并随浓度的增加而加强，但程度有限，不显示活性聚合特征；ＤＭＳＯ和ｎ－Ｂｕ４ＮＣｌ同时加入，表现出协同效应，不仅能保持较高的聚合反应活性，而且产物分子量分布很窄（Ｍｗ／Ｍｎ＝１．２７），分子量随单体转化率增加而增加，且线性关系良好，聚合物链数只与引发剂初始浓度相关，显示活性聚合特征。     

醋酸乙烯酯的可控/活性自由基聚合

概述了醋酸乙烯酯单体可控/活性自由基聚合的现状.总结了氮氧化合物存在下的聚合、原子转移自由基聚合、可逆加成断裂链转移聚合以及含碘化合物的衰减链转移聚合这四种活性自由基聚合方法用于醋酸乙烯酯聚合的研究结果,并对这四种方法作了简要的比较.     

Seleno‐containing poly(vinyl acetate) prepared by diselenocarbonates‐mediated controlled free radical polymerizations

The living free radical polymerizations of vinyl acetate (VAc) were successfully achieved in the presence of a novel organic selenium compound (diselenocarbonates), with 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. The living characteristics of the VAc polymerization were confirmed by the linear first‐order kinetic plots and linear increase of molecular weights (M_n) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions. In addition, the end of the polymers contains selenium element which may be useful in biotechnological and biomedical applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3159–3165     

Organometallic mediated radical polymerization of vinyl acetate with Fe(acac)2

The radical polymerization of vinyl acetate (VAc) is moderated by iron(II) acetylacetonate (Fe(acac)₂) by the organometallic route (OMRP), as well as by degenerative transfer polymerization (DTP) when in the presence of excess radicals, through the formation of thermally labile organometallic Fe^III dormant species. The poly(vinyl acetate) (PVAc)‐Fe^III(acac)₂ dormant species has been isolated in the form of an oligomer and characterized by ¹H NMR, EPR, and IR methods, and then used as a single‐component initiator for the OMRP of VAc. The degree of polymerization of this isolated oligomeric species demonstrates the limited ability of Fe(acac)₂, relative to the Co(acac)₂ congener, to rapidly trap the growing PVAc radical chain. Control under OMRP conditions is improved by the presence of Lewis bases, especially PMe₂Ph. On the other hand, iron(II) phthalocyanine inhibits the radical polymerization of VAc completely. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3494–3504     

Emulsion terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate: Experimental results

A systematic study of the terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate (BA/MMA/VAc) was conducted. In this stage of the study, batch emulsion terpolymerizations were performed in a 5 L stainless steel pilot plant reactor. The experiments were designed using a Bayesian (optimal) technique. The polymers produced were characterized for conversion, composition, molecular weight, and particle size. Conversion, terpolymer composition, number- and weight-average molecular weight, and average particle size results are discussed in light of the influence of seven factors and the interaction of these factors. The factors studied include monomer feed composition, initiator concentration, chain transfer agent concentration, impurity concentration, initiator type, emulsifier concentration, and temperature. A “two-stage rate” phenomenon, similar to that occurring in bulk co- and terpolymerization and emulsion copolymerization of acrylic/vinyl acetate systems was observed in the conversion, composition and molecular weight data. Furthermore, an interesting yet often ignored effect of impurities on emulsion polymerization kinetics was explained. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1659–1672, 1997     

利用反向原子转移自由基聚合反应合成聚甲基丙烯酸缩水甘油酯

以偶氮二异丁腈为引发剂,CuBr2/bpy为催化体系,甲基丙烯酸缩水甘油酯(GMA)通过反向原子转移自由基聚合反应合成了聚甲基丙烯酸缩水甘油酯(PGMA),其结构经1H NMR,IR和GPC确证。聚合反应符合活性自由基聚合特征,在聚合过程中GMA转化率和PGMA分子量随反应时间的延长而增大,分子量分布较窄。     

Mn2(CO)10‐induced controlled/living radical copolymerization of vinyl acetate and methyl acrylate: Spontaneous formation of block copolymers consisting of gradient and homopolymer segments

The controlled/living radical polymerization of vinyl acetate (VAc) and its copolymerization with methyl acrylate (MA) were investigated in bulk or fluoroalcohols using manganese complex [Mn₂(CO)₁₀] in conjunction with an alkyl iodide (R? I) as an initiator under weak visible light. The manganese complex induced the controlled/living radical polymerization of VAc even in the fluoroalcohols without any loss of activity. The R? I/Mn₂(CO)₁₀ system was also effective for the copolymerization of MA and VAc, in which MA was consumed faster than VAc, and then the remaining VAc was continuously and quantitatively consumed after the complete consumption of MA. The ¹H and ¹³C NMR analyses revealed that the obtained products are block copolymers consisting of gradient MA/VAc segments, in which the VAc content gradually increases, and homopoly(VAc). The use of fluoroalcohols as solvents increased the copolymerization rate, controllability of the molecular weights, and copolymerizability of VAc. The saponification of the VAc units in poly(MA‐grad‐VAc)‐block‐poly(VAc) resulted in the corresponding poly(MA‐co‐γ‐lactone)‐block‐poly(vinyl alcohol) due to the intramolecular cyclization between the hydroxyl and neighboring carboxyl groups in the gradient segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1343–1353, 2009     

醋酸乙烯(VAc)的活性/可控自由基聚合

本文综述了醋酸乙烯(VAc)单体的活性/可控自由基聚合研究进展.醋酸乙烯是一种重要的单体,是生产聚醋酸乙烯(PVAc)和聚乙烯醇(PVA)的原料.传统的自由基聚合方法如溶液、乳液、悬浮和分散等都可以用来实现VAc的聚合,得到不同分子量的PVAc和PVA.由于醋酸乙烯增长自由基的高活性,存在向聚合物链的链转移从而导致聚合物的分子量分布比较宽,为了得到分子量分布更窄的聚合物,活性可控聚合方法也被用来实现VAc的聚合.     

Mechanistic insights into the cobalt-mediated radical polymerization (CMRP) of vinyl acetate with cobalt(III) adducts as initiators

Over the past few years, cobalt-mediated radical polymerization (CMRP) has proved efficient in controlling the radical polymerization of very reactive monomers, such as vinyl acetate (VAc). However, the reason for this success and the intimate mechanism remained basically speculative. Herein, two mechanisms are shown to coexist: the reversible termination of the growing poly(vinyl acetate) chains by the Co(acac)2 complex (acac: acetylacetonato), and a degenerative chain-transfer process. The importance of one contribution over the other strongly depends on the polymerization conditions, including complexation of cobalt by ligands, such as water and pyridine. This significant progress in the CMRP mechanism relies on the isolation and characterization of the very first cobalt adducts formed in the polymerization medium and their use as CMRP initiators. The structure proposed for these adducts was supported by DFT calculations. Beyond the control of the VAc polymerization, which is the best ever achieved by CMRP, extension to other monomers and substantial progress in macromolecular engineering are now realistic forecasts.     

Aspects of Living Radical Polymerization Mediated by Cobalt Porphyrin Complexes

Living radical polymerization (LRP) of methyl acrylate (MA), acrylic acid (AA), and vinyl acetate (VAc) mediated by cobalt(II) porphyrin complexes ((TMP)Co^II·, (TMPS)Co^II·) are reported. The polymeric products with relatively low polydispersity and controlled number average molecular weight (M_n) based on one polymer chain per cobalt complex demonstrate the living characters of the polymerization process. The formation of block copolymers of poly(methyl acrylate)‐b‐poly(vinyl acetate) (PMA‐b‐PVAc) and poly(methyl acrylate)‐b‐poly(vinyl pyrrolidone) (PMA‐b‐PVP) demonstrate another important feature of LRP and extend the application of cobalt porphyrin mediated radical polymerization to a wider array of functionalized monomers. Kinetic studies using ¹H NMR to follow the formation of orGano‐cobalt complexes reveal that two mechanisms, reversible termination (RT) and degenerative transfer (DT), occur during the polymerization process. MA and VAc polymerization mediated by cobalt porphyrin complexes are used to illustrate the properties of these two LRP pathways and evaluate the kinetic and thermodynamic properties for several of the central reactions.     

Copper(0)‐mediated radical copolymerization of vinyl acetate and acrylonitrile in DMSO at ambient temperature

In this work, Cu(0)‐mediated radical copolymerization of vinyl acetate (VAc) and acrylonitrile (AN) was explored. The polymerization was carried out at 25°C with 2,2′‐bipyridine as ligand and dimethyl sulfoxide as solvent. The copolymerization proceeded smoothly producing moderately controlled molecular weights at low VAc feed ratios. The high VAc feed ratios generated low polymerization rate and poorly controlled molecular weights. FTIR, ¹H NMR, and differential scanning calorimetry confirmed the successful obtaining of the copolymers. Based on ¹H NMR spectra, the reactivity ratios of VAc and AN were calculated to be 0.003 and 1.605, respectively. This work conveyed the first example for the Cu(0)‐mediated radical polymerization of AN and VAc, wherein VAc cannot be homopolymerized by Cu(0)‐mediated radical polymerization technique. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012