FeBr3/Me6TREN催化MMA反向原子转移自由基聚合研究

对FeBr3/Me6TREN催化的反向原子转移自由基聚合进行了研究.在不同的催化剂、引发剂的配比、聚合温度和配体用量等条件下,该催化体系催化的MMA聚合反应动力学为一级反应,聚合物分子量可控,分子量分布很窄,说明该体系催化的聚合反应为活性可控聚合.通过实验计算了反应的活化能,并利用UV光谱对催化剂进行了研究.     

溶剂热体系中甲基丙烯酸甲酯的原子转移自由基聚合

以FeCl3/ PPh3为催化体系,在无引发剂、溶剂热体系中进行甲基丙烯酸甲酯(MMA)的原子转移自由基聚合(ATRP)反应.考察了反应温度与还原剂对反应的影响.实验结果表明,在溶剂热体系中进行的MMA聚合反应符合"活性"/可控聚合,聚合过程中转化率和分子量随时间的增加而增大,所得聚甲基丙烯酸甲酯分子量分布较窄.     

溴化铜对异丙醇铝存在下原子转移自由基聚合的影响

研究了以2-溴异丁酸乙酯为引发剂、溴化亚铜(CuX)/联二吡啶(bPy)/异丙醇铝[Al(OPrⁱ)₃]为三元复合催化体系,40℃下甲基丙烯酸甲酯(MMA)在环己酮中的原子转移自由基聚合,详细研究了溴化酮对聚合反应的影响.实验结果表明,以异丙醇铝为助催化剂,MMA可在较低温度下进行活性聚合;随着CuBr₂浓度的提高,自由基浓度降低,终止反应受到抑制;不加CuBr₂时,聚合物的分子量分布较宽(M_w/Mn);加入CuBr₂时,聚合物的分子量分布较窄(M_w/Mn=1.2～1.5),而且对数转化率与时间呈线性关系.     

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     

采用RATRP沉淀聚合法合成聚合物PMMA和PSt

以甲基丙烯酸甲酯(MMA)或苯乙烯(St)为单体,偶氮二异丁腈(AIBN)为引发剂,乙醇为溶剂,CuCl2/PMDETA(N,N,N’,N″,N″-五甲基二乙烯基三胺)为催化体系,MMA或St经反向原子转移自由基沉淀聚合法合成了聚合物PMMA或PSt。研究结果表明:PMMA和PSt的分子量分布较窄(Mw/Mn<1.3),聚合反应速率对单体呈一级动力学特征,数均分子量与单体转化率呈线性关系。反应具有"活性"/可控聚合的特征。     

采用ATRP合成天然橡胶接枝共聚物——Ⅲ.NR-g-PMMA的制备

N-溴代丁二酰亚胺与天然橡胶(NR)反应合成了大分子引发剂——溴代天然橡胶[NR-Br(1)].通过原子转移自由基聚合(ATRP),以CuBr/PMDTA为催化体系,1引发甲基丙烯酸甲酯(MMA)接枝共聚制得新型天然橡胶-g-聚甲基丙烯酸甲酯[NR-g-PMMA(2)],其结构经1H NMR和IR表征.初步聚合反应动力学研究结果表明,NBS与NR在高温下反应容易伴随双键加成和环化反应,于室温反应所得1具有较高的引发活性;接枝聚合符合一级动力学反应,即2的分子量随MMA单体转化率的提高而增加.     

ACPMA/BPO引发甲基丙烯酸甲酯聚合及其动力学

以4,4′-偶氮二[4-氰基戊酰(对-二甲氨基)苯胺](ACPMA)/过氧化二苯甲酰(BPO)为氧化还原引发体系,研究了甲基丙烯酸甲酯(MMA)在N,N-二甲基甲酰胺(DMF)中的聚合及其动力学行为.考察了聚合反应温度、单体浓度、ACPMA浓度和BPO浓度对聚合反应速率和聚合物分子量的影响,测定了反应级数和聚合反应的活化能.结果表明,在一定范围内,聚合反应速率随单体浓度增大、ACPMA浓度增大、BPO浓度增大和反应温度的升高而增大;聚合物分子量随单体浓度的增大而增大,随ACPMA浓度的增大、BPO浓度增大和反应温度的升高而降低.该体系具有氧化还原引发体系的特征,其引发MMA的聚合速率方程为Rp=K[ACPMA]0.57     

甲基丙烯酸甲酯的反向原子转移自由基聚合反应 研究

在较低的温度(60℃)和较低的AIBN/CuCl~2/配位剂摩尔比(1:2:4)条件下,用乙腈为溶剂,实现了甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合(RATRP)。联二吡啶(bpy)为配位剂时,所合成的聚甲基丙烯酸甲酯(PMMA)的分子量分布可低至1.08。用1,10-菲咯啉(phen)代替bpy,MMA的聚合反应速率加快,但其分子量分布稍宽(1.40左右),并进一步研究了bpy和phen作为混合配位剂时对MMA反向ATRP聚合的影响。用RATRP反应所得的带有卤素端基的PMMA作为苯乙烯ATRP的大分子引发剂,成功地合成了具有预期结构的苯乙烯与甲基丙烯酸甲酯嵌段共聚物,大分子引发剂的引发效率接近于1,说明在RATRP过程中由自由基引发剂引发MMA进行一般自由基聚合反应的可能性甚微。     

PADC-Cu(Ⅱ)/Na2SO3/H2O体系引发MMA聚合

由含N,O,S多官能团的螯合树脂PADC和Cu2 作用制得一种新型的高分子金属配合物,用IR、XPS、AAS、TG/DTA对其结构进行了表征.以该配合物和Na2SO3水溶液组成的体系应用于引发MMA聚合,结果表明:PADC-Cu(Ⅱ)/Na2SO3体系可以有效地引发MMA聚合,反应表观活化能Ea=57.4 kJmol-1,并详细研究了影响产率和分子量的各因素,由该体系引发MMA聚合的分子量可达213万,在6h内产率就达58.6%.初步讨论了该聚合过程是一种自由基聚合过程,初始自由基由PADC-Cu2 /Na2SO3/MMA体系“配位氢转移”产生.     

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。     

Synthesis of PMMA‐b‐PBA block copolymer in homogeneous and miniemulsion systems by DPE controlled radical polymerization

In this research, poly(methyl methacrylate)‐b‐poly(butyl acrylate) (PMMA‐b‐PBA) block copolymers were prepared by 1,1‐diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. First, monomer methyl methacrylate (MMA), initiator 2,2′‐azobisisobutyronitrile (AIBN) and a control agent DPE were bulk polymerized to form the DPE‐containing PMMA macroinitiator. Then the DPE‐containing PMMA was heated in the presence of a second monomer BA, the block copolymer was synthesized successfully. The effects of solvent and polymerization methods (homogeneous polymerization or miniemulsion polymerization) on the reaction rate, controlled living character, molecular weight (M_n) and molecular weight distribution (PDI) of polymers throughout the polymerization were studied and discussed. The results showed that, increasing the amounts of solvent reduced the reaction rate and viscosity of the polymerization system. It allowed more activation–deactivation cycles to occur at a given conversion thus better controlled living character and narrower molecular weight distribution of polymers were demonstrated throughout the polymerization. Furthermore, the polymerization carried out in miniemulsion system exhibited higher reaction rate and better controlled living character than those in homogeneous system. It was attributed to the compartmentalization of growing radicals and the enhanced deactivation reaction of DPE controlled radical polymerization in miniemulsified droplets. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4435–4445, 2009     

活性正离子聚合与原子转移自由基聚合转换合成聚β-蒎烯接枝共聚物

通过活性正离子聚合与原子转移自由基聚合(ATRP)转换合成了β-蒎烯与甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、苯乙烯(St)的新型接枝共聚物.首先以α-氯代乙苯/TiCl4/Ti(OiPr)4/nBu4NCl体系引发β-蒎烯活性正离子聚合,合成预定分子量大小和窄分子量分布的聚β-蒎烯,然后经N-溴代琥珀酰亚胺(NBS)定量溴化,得到溴化聚β-蒎烯大分子引发剂(Br/β-蒎烯链节摩尔比为0.5).然后将该大分子引发剂与溴化亚铜(CuBr)/2,2′-联吡啶(bpy)复合,引发MMA、BA、St进行ATRP接枝聚合.接枝反应显示一级动力学特征,且产物的分子量及分子量分布可控,表明上述ATRP接枝聚合反应具有可控聚合特征.接枝产物的结构经1H-NMR分析得到进一步证实.     

Narrow-disperse Highly Cross-linked “Living” Polymer Microspheres by Two-stage Precipitation Polymerization

Narrow-disperse, surface-functionalized "living" polymer microspheres with uniformly cross-linked structures were prepared by two-stage precipitation copolymerization of styrene and divinylbenzene. The two-stage precipitation polymerization is composed of an initial conventional precipitation polymerization for the nucleation followed by a reverse atom transfer radical polymerization(reverse ATRP) for the controlled polymerization process. The polymerization parameters(including reaction time for the first stage, AIBN amount and monomer loading) have been studied to show significant influences on the morphologies. Moreover, narrower size distribution and an ATRP initiator-functional surface of resulting particles can be obtained by applying reverse ATRP to conventional precipitation polymerization in the second stage. Furthermore, the "livingness" of the resulting polymer microspheres was testified by their surface modification of poly[2-(dimethylamino) ethyl methacrylate](PDMAEMA) brushes via surface-initiated ATRP(SI-ATRP).     

Photoirradiated Fe-Mediated AGET ATRP of Methyl Methacrylate in the Presence of Alcohol

In this study, photoirradiated Fe-mediated AGET (activators generated by electron transfer) atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was investigated at ambient temperature in N,N-dimethylformamide (DMF) using carbon tetrachloride as initiator, FeCl₃·6H₂O/bipyridine (Bpy) as catalyst complex, and alcohol as reducing agent. Linear semi-logarithmic plot of conversion vs. time was obtained from the kinetic experiments, and the number-average molecular weight increased linearly with monomer conversion and corresponded to the theoretic values with molecular weight distributions (M_w/M_n) as low as 1.25, which agreed with the character of controlled/living polymerization. The kinds of alcohol played an important role in photoirradiated Fe-mediated AGET ATRP of MMA. The living characteristics were demonstrated through chain extension experiment. The obtained polymer was characterized by proton nuclear magnetic resonance (NMR) and gel permeation chromatography.     

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。     

以双硫酯为链转移剂的活性自由基聚合

合成并研究了两种双硫酯链转移剂的纯化方法 ,进行了多种单体以双硫酯为链转移剂的活性自由基聚合及嵌段共聚 .发现以PhC(S)SC(CH3) 2 Ph为链转移剂的效果比PhC(S)SCH(CH3)Ph好 ,聚合产物的多分散性系数较小 .引发剂与链转移剂的摩尔数比为 1∶3 5～ 1∶4 2时 ,得到多分散性系数小 ,实测分子量与理论分子量相近的聚合产物 .聚合物的分子量随时间和转化率的增加而增加 ,加入第二单体形成嵌段共聚物 ,具有活性聚合特征 .聚甲基丙烯酸酯大分子引发剂引发丙烯酸酯单体聚合时 ,聚合速度最快 .     

2‐[(Diphenylphosphino)methyl]pyridine as ligand for iron‐based atom transfer radical polymerization

2‐[(Diphenylphosphino)methyl]pyridine (DPPMP) was successfully used as a bidentate ligand in the iron‐mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) with various initiators and solvents. The effect of the catalytic system on ATRP was studied systematically. Most of the polymerizations with DPPMP ligand were well controlled with a linear increase in the number‐average molecular weights (M_n) versus conversion and relatively low molecular weight distributions (M_w/M_n = 1.10–1.3) being observed throughout the reactions, and the measured molecular weights matched the predicted values. Initially added iron(III) bromide improved the controllability of the polymerization reactions in terms of molecular weight control. The ratio of ligand to metal influenced the controllability of ATRP system, and the optimum ratio was found to be 2:1. It was shown that ATRP of MMA with FeX₂/DPPMP catalytic system (X = Cl, Br) initiated by 2‐bromopropionitrile (BPN) was controlled more effectively in toluene than in polar solvents. The rate of polymerization increased with increasing the polymerization temperature and the apparent activation energy was calculated to be 56.7 KJ mol^?1. In addition, reverse ATRP of MMA was able to be successfully carried out using AIBN in toluene at 80 °C. Polymerization of styrene (St) was found to be controlled well by using the PEBr/FeBr₂/DPPMP system in DMF at 110 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2922–2935, 2008     

Reverse atom transfer radical polymerization of methyl methacrylate in room‐temperature ionic liquids

The reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out in 1‐butyl‐3‐methylimidazolium hexafluorophosphate with 2,2′‐azobisisobutyronitrile/CuCl₂/bipyridine as the initiating system, which had been reported as not able to promote a controlled process of MMA in bulk. The living nature of the polymerization was confirmed by kinetic studies, end‐group analysis, chain extension, and block copolymerization results. The polydispersity of the polymer obtained was quite narrow, with a weight‐average molecular weight/number‐average molecular weight ratio of less than 1.2. In comparison with other reverse ATRPs in bulk or conventional solvents, a much smaller amount of the catalyst was used. After a relatively easy removal of the polymer and residue monomer, the ionic liquid and catalytic system could be reused without further treatment. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 143–151, 2003     

镍体系(NiCl_2/PPh_3)催化的反向原子转移自由基聚合

以 2 ,3 二氰基 2 ,3 二苯基丁二酸二乙酯 (DCDPS) NiCl2 PPh3 为引发体系 ,首次利用Ni2 + 和Ni+ 之间的变价关系 ,研究了乙烯基单体的反向ATRP .结果表明 ,苯乙烯 (St)的聚合具有活性自由基聚合的特征 ,所得PSt的分子量随转化率的增加而增加 ,并且制得的PSt可以作为大分子引发剂进行扩链反应 .但该引发体系引发甲基丙烯酸甲酯 (MMA)聚合时没有活性自由基聚合特征 ,PMMA的分子量与转化率基本无关 ,但分子量分布窄Mw Mn=1 19