高分子合成新方法：活性自由基聚合

1、活性自由基聚合,材料与化学化工学部,自由基聚合,活性聚合,活性”自由基聚合,结合两者的长处，可以方便 的实施乙烯基类单体的自由基 聚合，实现聚合物合成设计,传统的自由基聚合具有单体广泛、合成工艺多样、操作简便、工业化成本低等优点,不能控制聚合物分子的结构和大小，通常聚合物分子量分布宽,引发速率远大于增长速率，不存在链终止和链转移，分子量分布很窄，即具有单分散性(Mw/Mn1)，可控制聚合度，聚合物的分子量随转化率线性增长，可合成具有预定结构的嵌段共聚物。反应条件比较苛刻，工艺复杂，工业化成本高，单体覆盖面较窄，分子结构的可设计性较小,2,重要的“活性”自由基聚合方法,引发-转移-终止剂法聚合

2、（Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,3,重要的“活性”自由基聚合方法,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,T. Otsu, J. Polym. Sci. Part A: Polym. Chem., Vol. 38, 21212136 (2000,4,In 1956, he found that polymers derived from thiuram disulfides could induce p

3、hotopolymerization to give block and graft copolymers. This discovery became the foundation for this highlight. For his work, he was awarded a D.Sc. degree from Osaka University in 1959 and went to the USA to work as a research associate with Professor Carl S. Marvel at the University of Illinois fo

4、r a year. Then, he returned to Osaka City University and was appointed Associate Professor. In 1965, he accepted the position of Full Professor of Polymer Chemistry and worked there for 26 years,Dr. Takayuki Otsu is a Professor Emeritus, Osaka City University. He was born in Osaka in 1929 and receiv

5、ed his B.Sc. degree from the Osaka Institute of Science and Technology in 1951. He then was appointed as an instructor at Osaka City University and started his research work on radical polymerization under the late Professor Minoru Imoto,After his retirement in 1992, he moved to Kinki University as

6、Professor until his retirement in 1999. The main topics of his research are the various fields of radical polymerization: basic studies of rates and mechanisms, new monomers and initiators, monomer structurereactivity relationships, controlled polymer syntheses with the iniferter and living radical

7、polymerization techniques. He is the author or coauthor of more than 550 original papers, 120 review articles, 10 books, 30 book chapters, and more than 100 patents. Dr. Otsu was invited abroad to more than 40 International Symposiums, universities, and laboratories to give various lectures. He was

8、also a chairman of the Japanese side of the JapanChina Symposium on Radical Polymerization (now the Asia Polymer Symposium) from 1980 to 1990,In 1951, I started to work under Professor M. Imoto at Osaka City University, on the radical polymerization of vinyl chloride (VC) with BPO/dimethylaniline as

9、 an initiator, and I published two articles on the initiation mechanism in 1955. In those days, two new polymers, high-density polyethyleneand isotactic polypropylene,were discovered with novel initiators, and the initiation mechanism for radical polymerization was also discussed by several workers.

10、 In 1953, the definition of block and graft copolymers was clarified by Mark, who emphasized that some physical properties were different from those of random and alternating copolymers. After that, the synthesis of these polymers has been attempted with several methods in which the block copolymer

11、of St and MMA is prepared with polymeric radical initiators and the living polymer discovered by Szwarc in 1956,This being the case, I had an interest in new initiators and their mechanisms, and I focused my attention on the unique reaction behavior of organic sulfur compounds, which have been used

12、as a thiyl radical source, an accelerator, a modifier, a terminator for vinyl or diene polymerization, and an accelerator for vulcanization in the rubber industry,In 1954, we began to examine the initiating ability of these compounds in radical polymerization of St and MMA and found in 1956 that var

13、ious sulfides and disulfides (e.g., phenyl, benzoyl, benzothiazoyl, thiuram, and dithiocarbamate derivatives) could serve as efficient photoinitiators. (Otsu, T. J Polym Sci 1956, 21, 559; Otsu, T.; Nayatani, K.; Muto, I.; Imai, M. Makromol Chem 1958, 27, 142.,重要的“活性”自由基聚合方法,稳定自由基聚合 （Stable Free Rad

14、ical Polymerization, SFRP,氮氧自由基,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,9,重要的“活性”自由基聚合方法,稳定自由基聚合 （Stable Free Radical Polymerization, SFRP,氮氧自由基,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,M. K. Georges, R.P.N. Veregin, P. M. Kazmaier, an

15、d G. K. Hamer, Macromolecules 26, 2987 (1993,10,稳定自由基聚合 （Stable Free Radical Polymerization, SFRP,原子转移自由基聚合 （Atom Transfer free Radical Polymerization, ATRP,氮氧自由基,引发剂,催化剂/配体,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,11,Wang, J. S.; Matyjaszewski, K. Macromolecules 1995

16、, 28, 7901-7910,Kato, M.; Kamigaito, M.; Sawamoto, M.; Higashimura, T. Macromolecules 1995, 28, 1721-1723,稳定自由基聚合 （Stable Free Radical Polymerization, SFRP,原子转移自由基聚合 （Atom Transfer free Radical Polymerization, ATRP,可逆加成断裂链转移自由基聚合 （Reversible Addition-Fragmentation chain Transfer Polymerization, RAFT

17、,氮氧自由基,引发剂,催化剂/配体,链转移剂(RAFT试剂,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,12,Rizzardo, E. et.al.,Macromolecules, 1998, 31, 5559-5562,稳定自由基聚合 （Stable Free Radical Polymerization, SFRP,原子转移自由基聚合 （Atom Transfer free Radical Polymerization, ATRP,可逆加成断裂链转移自由基聚合 （Reversible Ad

18、dition-Fragmentation chain Transfer Polymerization, RAFT,氮氧自由基,引发剂,催化剂/配体,链转移剂(RAFT试剂,引发-转移-终止剂法聚合 （Initiator-Transfer agent-Terminator, Iniferter,Iniferter试剂,单电子转移活性自由基聚合 Single-Electron Transfer Living Radical Polymerization, SET-LRP,引发剂,Cu(0)/配体 极性溶剂，可以在室温，以极快的速率进行聚合,13,Virgil Percec. et al. J. A

19、m. Chem. Soc. 2006, 128, 14156-14165,14,活性自由基聚合由于其基本控制原理相同，都是通过建立活性种与休眠种的可逆平衡,因此不同活性自由基聚合机理应该可以相互转变或共存。关键是X的选择,15,Iniferter 聚合机理和稳定自由基聚合机理共存 Iniferter 聚合机理向ATRP聚合机理转变 RAFT聚合机理向ATRP聚合机理转变 RAFT聚合机理向SET-LRP聚合机理转变,Iniferter 试剂作为稳定自由基聚合引发剂,通常使用两类物质（偶氮和过氧化合物，AIBN和BPO）作为氮氧稳定自由基双分子调控体系中的引发剂。常规自由基引发剂的不可逆的分解使

20、得在高温下初级自由基的浓度很高，不利于聚合的控制,16,Iniferter 试剂作为稳定自由基聚合引发剂,引入TMTD作为双分子氮氧稳定自由基聚合体系中的引发剂，TMTD分解速率常数要明显低于常规自由基引发剂的分解速率。由于iniferter的可逆的断裂，引发阶段的初级自由基浓度要比常规的氮氧稳定自由基双分子体系低。当TEMPO/TMTD的摩尔比为1.2/1时，就可以很好的控制聚合过程，聚合速率显著提高，分子量分布较窄。并且，得到的聚苯乙烯具有紫外敏感的SC(S)N(CH3)2官能团末端基,Xu, Wenjian; Zhu, Xiulin; Cheng, Zhenping; Chen, Gao

21、jian; Zhu, Jian J. Polym. Sci. Part A: Polym. Chem. 2005, 43, 543-551,17,Xu, Wenjian; Zhu, Xiulin; Cheng, Zhenping; Chen, Gaojian; Zhu, Jian J. Polym. Sci. Part A: Polym. Chem. 2005, 43, 543-551,18,Xu, Wenjian; Zhu, Xiulin; Cheng, Zhenping; Chen, Gaojian; Zhu, Jian J. Polym. Sci. Part A: Polym. Chem

22、. 2005, 43, 543-551,Iniferter 聚合机理和稳定自由基聚合机理并存,19,T. Dot, A. Matsumoto, and T. Otsu, J. Polym. Sci. Part A: Polym. Chem., Vol. 32,2241-2249 (1994,20,Xu, Wenjian; Zhu, Xiulin; Cheng, Zhenping; Chen, Gaojian; Zhu, Jian J. Polym. Sci. Part A: Polym. Chem. 2005, 43, 543-551,GPC curves of PSt (a). after

23、chain extension at 123 oC (b).before; Polymerization time = 6h, conversion = 60 %; Styrene0 = 8.7 M; Macroinitiator0 = 0.0331 M,GPC curves of PSt a). after chain extension under UV light at room temperature b).before; Styrene0 = 8.7M, pre-PSt0 = 0.023M,21,Elution Time (min,Elution Time (min,22,Inife

24、rter 聚合机理向ATRP聚合机理转变,引发剂,催化剂,配 体,CuBr,EBiB,PMDETA,EDCIB,or EDDCB EDCIB 和 EDDCB 是常规的Iniferter 试剂,23,Table 1 The results of bulk Polymerization of St initiated by EDCIB,Conditions: St0 = 8.68 mol/L, in bulk, temperature = 115 C Ratio = St0/EDCIB0/CuBr0/PMDETA0,Wei Zhang, Xiulin Zhu*, Zhenping Cheng an

25、d Jian Zhu, J. Appl. Poly. Sci., Vol. 106, 230237 (2007,1.84,1.06,24,400 MHz 1H NMR spectroscopy of the PS-D (in CDCl3). St-D0/EDDCB0/CuBr0/PMDETA0 = 50:1:2:6 ,115 oC Mn(PS-D) = 5600, Mw/Mn = 1.20,25,GPC curves of the polymers before and after chain extension (1) St0/Macroinitiator0/CuBr0/PMDETA0 =

26、100:1:2:6, St/Cyclohexanone = 1:1 (v/v), 115 oC, 5 h, conversion% = 82.6%. (2) MMA0/Macroinitiator0 = 2000:1, UV irradiation at rt. 27 h, conversion: 26.9,1 by ATRP,2 by Iniferter,Elution Time (min,Mechanism of ATRP Polymerization,Wang, J. S.; Matyjaszewski, K. Macromolecules 1995, 28, 7901-7910,26,

27、RAFT聚合机理向ATRP聚合机理转变,Mechanism of RAFT Polymerization,Rizzardo, E. et. al. Macromolecules, 1998, 31, 5559-5562,27,RAFT 试剂,大分子 RAFT 试剂,RAFT to ATRP ,28,CuBr +,Zhengbiao Zhang, Wei Zhang, Xiulin Zhu*, Zhenping Cheng, and Jian Zhu, J. Polym. Sci. Part A: Polym. Chem., Vol. 45, 57225730 (2007,MMA0 = 9.40

28、 mol/L, CuBr0 = 0.01886 mol/L, PMDETA0 = 0.05658 mol/L, temperature = 115 oC,在MMA的RAFT聚合体系中加入CuBr/PMDETA，聚合速率随着CPDN浓度增加而增加，符合ATRP机理，与RAFT机理不符,29,CPDN浓度的影响,MMA0 = 9.40 mol/L, CPDN0 = 0.03771 mol/L, PMDETA0 = 0.05658 mol/L, temperature = 115 oC,随着CuBr浓度增加，聚合速率增加，符合ATRP机理,30,CuBr浓度的影响,MMA0 = 9.40 mol/L

29、, CPDN0 = 0.03771 mol/L, CuBr0 = 0.01885 mol/L, temperature = 115 oC,随着PMDETA浓度增加，聚合速率增加，符合ATRP机理,31,PMDETA浓度的影响,MMA0 = 9.40 mol/L, Temperature = 115 oC,RAFT聚合,CuBr/PMDETA,ATRP,在MMA的RAFT聚合体系中加入ATRP的催化剂/配体，聚合机理发生了从RAFT向ATRP的转变，其中RAFT试剂部分充当了ATRP中引发剂的作用,32,33,在MMA的RAFT聚合体系中加入ATRP的催化剂/配体CuBr/PMDETA ,得到的

30、PMMA经核磁表征，末端含CPDN的二硫代酯碎片,1H NMR spectrum of PMMA (Mn,GPC = 5800 g/mol, Mw/Mn = 1.33,由于得到的PMMA末端含CPDN的二硫代酯碎片，可以作为大分子RAFT试剂或大分子ATRP引发剂，分别以RAFT方法和ATRP法的进行扩链反应,以RAFT方法扩链 MMA0/PMMA0 = 500/1, 115 oC, MMA0 = 9.40 mol/L, 20 h, 72.1% conversion,以ATRP方法扩链MMA0/PMMA0/CuBr0/PMDETA0 = 500/1/0.5/0.5, 115 oC, MMA0

31、= 9.40 mol/L, 20 h, 91.8% conversion,34,35,RAFT聚合机理向SET-LRP聚合机理转变,单电子转移“活性”自由基聚合 (SET-LRP)机理,Virgil Percec. et al. J. Am. Chem. Soc. 2006, 128, 14156-14165,SET-LRP由Percec等人提出，并认为是与ATRP不同的聚合机理。SET-LRP是以Cu(0)和配体作为起始催化剂。Cu(0)作为电子的给体，含卤素引发剂或者末端含卤素的休眠大分子链作为电子受体，首先生成阴离子自由基R-X- 和一价铜离子Cu+的紧密离子对。 R-X-通过键的异裂产

32、生自由基(R)以及Cu(I)X,R引发聚合生成增长链自由基。产生的Cu(I)X在极性溶剂的作用下，以极快的速度原位歧化成Cu(0)和Cu(II)X2，该原位生成的Cu(0)异常活泼地参与单电子转移。Cu(II)X2与增长自由基的钝化过程是其活化过程的逆反应。增长自由基与Cu(II)X2作用，生成Pn-X- 与 Cu(II)X+的紧密离子对，进一步产生Cu(I)X和休眠的增长链Pn-X, 从而实现了对聚合过程的控制,36,原位歧化,37,Proposed Catalytic Cycle of SET-LRP Mediated By Cu(0) Species in Polar Media by

33、a low activation energy outer-sphere single-electron-transfer (SET) mechanism,Virgil Percec. et al. J. Am. Chem. Soc. 2006, 128, 14156-14165,38,Cu(0) +,RAFT to SET-LRP ,Macromolecules 2010, 43, 79797984,MMA0 = 6.28 mol/L, MMA/DMSO = 2/1 (v/v), Temperature = 25 oC,RAFT聚合,SET-LRP,以CPDN作为RAFT试剂， 25oC下MMA的RAFT聚合在72 h内无聚合物产生。而在此体系中加入Cu(0)/PMDETA后，聚合则能以较快速率进行；并且CPDN浓度增加，聚合速率增加，符