酚氧基联烯基醚单体的原子转移自由基聚合研究

以具有较高活性的酚氧基联烯基醚(POA)和对叔丁基酚氧基联烯基醚(t-BuPOA)为研究对象, 研究了不同引发 剂/配体体系对其原子转移自由基(ATRP)聚合行为的影响. 发现在2-溴代丙酸甲酯/溴化亚铜/4,4’-二庚基联吡啶(2-MBP/CuBr/dHbpy)和对甲苯磺酰氯/溴化亚铜/三-(N,N-二甲基氨基乙基)胺(p-TsCl/CuBr/Me6TREN)两种ATRP反应体系中, POA的聚合都遵循ATRP反应的机理.     

离子液体中单电子转移活性自由基聚合法制备星形聚丙烯酰胺

以季戊四醇为原料,合成了2,2-二溴甲基-1,3-二溴丙烷(PEBr4),并以此为四官能度引发剂,Cu0粉/三-(2-二甲氨基乙基)胺(Me6-TREN)为催化体系,在离子液体中实现了丙烯酰胺(AM)的单电子转移活性自由基聚合(SET-LRP),得到了窄分子量分布的星形聚丙烯酰胺(PAM),Mw/Mn约为1.26(MGPCn=14.1×103,转化率为43.4%)。 采用1H NMR对PAM结构进行表征确认,并采用GPC测定了PAM的分子量及分子量分布;考察了水、单体/催化剂(引发剂)配比对聚合反应的影响。 结果表明,少量水的加入能够加快聚合反应,使链增长速率常数由kappp=0.042 4 h-1增加至kappp=0.148 6 h-1;催化剂、引发剂用量越大,AM的SET-LRP的聚合反应速率越快,聚合反应的可控性越好,Mn随催化剂用量的增大及引发剂用量的减小而增大,且与理论分子量相近,分子量分布均呈下降趋势。     

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.     

苯乙烯的单电子转移活性自由基聚合

以2,2-二溴甲基-1,3-二溴丙烷（PEBr4）为引发剂,Cu0粉/三（2-二甲氨基乙基）胺（Me6-TREN）为催化体系,在二甲亚砜（DMSO）和H2O的混合溶剂中实现了苯乙烯（St）的单电子转移活性自由基聚合（SET-LRP）。 通过1H NMR和GPC分析表明,所得聚合物为星形结构并具有较窄的分子量分布Mw/Mn=1.20（MGPCn=25.3×103,转化率为42.6%）,且聚合物的链端保留了-Br端基。 考察了溶剂、反应温度及相转移催化剂对聚合的影响,结果表明,混合溶剂中H2O的体积分数由10%增加至20%导致了聚合速率的降低,表观聚合速率常数（kappp）由0.026 4 h-1减小至0.019 7 h-1;升高反应温度、增加催化剂用量以及相转移催化剂的加入分别导致聚合体系的kappp增加,同时,催化剂用量的增加和相转移催化剂的加入使聚合物的分子量分布系数降低。     

光学活性两亲性嵌段共聚物的合成与表征

以溴封端聚乙二醇单甲醚(MPEG-Br)为大分子引发剂,三(2-二甲氨基乙基)胺(Me6TREN)/溴化亚铜(CuBr)为催化体系,通过原子转移自由基聚合(ATRP)反应制备了不同嵌段比例且分子量分布较窄的光学活性聚乙二醇单甲醚嵌段聚(N-甲基丙烯酰-L-亮氨酸甲酯)(MPEG-b-PMALM)聚合物.以1H-NMR表征了其化学结构以及两嵌段的比例.通过热重分析(TGA)和示差扫描量热仪(DSC)研究了嵌段共聚物的热学性能.相对于单体的旋光度,共聚物在聚合过程中旋光度发生了反转,其旋光度的绝对值显著增加,且随着PMALM嵌段含量的增加而增加.圆二色谱法(CD)结果表明,嵌段共聚物分子主链形成了一种无规卷曲的二级构象结构,其光学活性亦随PMALM含量的增加而增强.     

α-二亚胺镍(Ⅱ)催化甲基丙烯酸甲酯聚合

以4种不同结构的α-二亚胺镍(Ⅱ)催化剂[(t-Bu)—N CH—CH N—(t-Bu)]NiBr2(C1),[C6H5—N C(Me)—C(Me)N—C6H5]NiBr2(C2),[(2,6-C6H3(Me)2)—N C(Me)—C·(Me)N—(2,6-C6H3(Me)2)]NiBr2(C3)和[(2,6-C6H3(i-Pr)2)—N C(An)—C(An)N—(2,6-C6H3(i-Pr)2)]NiBr2(An=acenaphthyl)(C4),在甲基铝氧烷(MAO)作用下,对甲基丙烯酸甲酯(MMA)进行催化聚合.以C2为模型催化剂系统研究了Al/Ni摩尔比、单体浓度、聚合温度、聚合时间和反应溶剂对催化活性及聚合物分子量的影响.在较适合的聚合条件(催化剂用量为1.6μmol,Al/Ni摩尔比为800,MMA浓度为2.9 mol/L,甲苯为溶剂,聚合温度为60℃,聚合时间为4 h)下,讨论了催化剂结构对催化活性和聚合物分子量的影响.研究发现,催化剂C1~C3催化MMA聚合均得到富含间规结构的聚甲基丙烯酸甲酯(PMMA).催化剂结构中空间位阻增大导致催化活性降低,空间位阻最小的C1催化活性最高[达107.8 kg/(mol Ni·h)];而空间位阻最大的C4催化活性仅为7.8 kg/(mol Ni·h).催化剂结构中给电子效应增加有利于催化活性及聚合物分子量的增加.C2催化活性为62.5 kg/(mol Ni·h),所得聚合物的分子量为5.0×104;而具有较强给电子效应的C3催化活性达到96.9 kg/(mol Ni·h),并得到更高分子量的聚合物(7.6×104).     

新型含硅聚芳醚酮的合成与表征

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。     

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。     

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     

SiO2负载的后过渡金属配合物／三乙基铝催化乙烯聚合研究

将后过渡金属配合物{[2,6-ArN=C(Me)2C5H3N]FeCl2} ( Ar=2,6-iPr2C6H3) Ⅰ负载于SiO2上, 并与三乙基铝(AlEt3)组成催化剂体系并催化乙烯聚合. 考察了Al/Fe比(AlEt3/催化剂摩尔比)、聚合温度对催化剂活性、聚乙烯(PE)分子量、熔融温度以及结晶度的影响. 在Al/Fe比为750、聚合温度为40 ℃时, 催化剂活性达到7.07×105g PE·(mol Fe·h)-1. 实验所得聚合物的分子量为1.05×105～2.33×105 g/mol, 熔融温度高达132 ℃左右,结晶度在44.2%～77.8%之间.     

On surface-initiated atom transfer radical polymerization using diazonium chemistry to introduce the initiator layer

This work features the controllability of surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate, initiated by a multilayered 2-bromoisobutyryl moiety formed via diazonium chemistry. The thickness as a function of polymerization time has been studied by varying different parameters such as the bromine content of the initiator layer, polarity of reaction medium, ligand type (L), and the ratio of activator (Cu(I)) to deactivator (Cu(II)) in order to ascertain the controllability of the SI-ATRP process. The variation of thickness versus surface concentration of bromine shows a gradual transition from mushroom to brush-type conformation of the surface anchored chains in both polar and nonpolar reaction medium. Interestingly, it is revealed that very thick polymer brushes, on the order of 1 μm, can be obtained at high bromine content of the initiator layer in toluene. The initial polymerization rate and the overall final thickness are higher in the case of nonpolar solvent (toluene) compared to polar medium (acetonitrile or N,N-dimethylformamide). The ligand affects the initial rate of polymerization, which correlates with the redox potentials of the pertinent Cu(II)/Cu(I) complexes (L = Me(6)TREN, PMDETA, and BIPY). It is also observed that the ability of polymer brushes to reinitiate depends on the initial thickness and the solvent used for generating it.     

Atom transfer radical polymerization of methyl methacrylate catalyzed by cobalt catalyst system

A new catalyst system, CoCl₂/tris(2‐(dimethyl amino) ethyl)amine (Me₆ TREN), was used to catalyze the polymerization of methyl methacrylate (MMA) successfully through atom transfer radical polymerization mechanism. The control over the polymerization was not ideal, the molecular weight distribution of the resulting polymer (PMMA) was relatively broad (M_w/M_n = 1.63–1.80). To improve its controllability, a small amount of hybrid deactivator (FeBr₃/Me₆TREN or CuBr₂/Me₆TREN) was added in the cobalt catalyst system. The results showed that the level of control over the polymerization was significantly improved with the hybrid cobalt–iron (or cobalt–copper) catalyst system; the polydispersity index of the resulting polymer was reduced to a low level (M_w/M_n = 1.15–1.46). Furthermore, with the hybrid cobalt–iron catalyst, the dependence of the propagation rate on the temperature and the copolymerization of methacrylate (MA) with PMMA‐Br as macroinitiator were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5207–5216, 2005     

Controlled Radical Polymerization of Methyl Methacrylate Catalyzed by Hybrid Supported Iron Catalyst

A supported iron catalyst, which was prepared by anchoring FeCl2/FeCl3 on the cross-linking macroporous polyacrylate ion exchange resin, was evaluated via the controlled radical polymerization. When a small amount of CuCl2/ Me6TREN was added, the controllability of the polymerization over the iron-mediated catalyst was significantly improved（Mw/Mn = 1.23-1.73 ）, affording a polymer with a low residual metal via a simple catalyst separation procedure. After suitable regeneration, the supported iron catalyst could also he recycled. UV-Vis analysis showed that the additional copper catalyst could facilitate the radical deactivation process.     

Atom transfer radical polymerization of methyl methacrylate catalyzed by ion exchange resin immobilized Co(II) hybrid catalyst

Ion exchange resin immobilized Co(II) catalyst with a small amount of soluble CuCl₂/Me₆TREN catalyst was successfully applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in DMF. Using this catalyst, a high conversion of MMA (>90%) was achieved. And poly(methyl methacrylate) (PMMA) with predicted molecular weight and narrow molecular weight distribution (M_w/M_n = 1.09–1.42) was obtained. The immobilized catalyst can be easily separated from the polymerization system by simple centrifugation after polymerization, resulting in the concentration of transition metal residues in polymer product was as low as 10 ppm. Both main catalytic activity and good controllability over the polymerization were retained by the recycled catalyst without any regeneration process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1416–1426, 2008     

Ambient temperature rapid ATRP of methyl acrylate, methyl methacrylate and styrene in polar solvents with mixed transition metal catalyst system

Ambient temperature atom transfer radical polymerization (ATRP) of methyl acrylate (MA), methyl methacrylate (MMA) and styrene (Sty) in the presence of polar solvents (dimethyl sulfoxide: DMSO, dimethylformamide: DMF and acetonitrile: MeCN) with a mixed transition metal catalyst system (Fe(0) as initial activator and CuBr₂/Me₆TREN complex as deactivator) provides a rapid synthesis of polymers with very low polydispersity (PDI) values and predetermined molecular weights. The polymethylacrylate (PMA) prepared using this novel approach contains the Br-terminated chain ends (functionality ∼100%) and can be successfully used for block copolymer synthesis (as demonstrated on the chain extension experiment performed using the PMA–Br macroinitiator). The key elementary reactions involved in this novel ATRP system and some preliminary mechanistic aspects of the process are also discussed.     

Cu(0) Wire-mediated Single-electron Transfer-living Radical Polymerization of Oligo(ethylene oxide) Methyl Ether Acrylate by Selecting the Optimal Reaction Conditions

The efficient Cu(0) wire-catalyzed single-electron transfer-living radical polymerization (SET-LRP) in organic solvents and mixtures of the organic solvents with water has been thoroughly investigated.Oligo(ethylene oxide) methyl ether acrylate was used as an exemplar oligomer monomer to determine the optimum polymerization conditions for rapid,controlled,and quantitative production of well-defined polymers.The effects of Cu(0)-wire length (12.5 or 4.5 cm),ligand type (tris(dimethylaminoethyl)amine,Me6-TREN,or tris(2-aminoethyl)amine,TREN),and solvent type (dipolar aprotic solvents,cyclic ethers,alcohol,or acetone) on the polymerization have been evaluated.Kinetic experiments were performed for all polymerizations to assess the "living" behavior of each system employed.Importantly,TREN could be used as a replacement for Me_6-TREN in Cu(0) wire-catalyzed SET-LRP of oligomer monomer,which probably provides the most economical and efficient methodology since TREN is 80 times less expensive than Me6-TREN.The high chain-end fidelity of resulting polymer was experimentally verified by thiol-Michael addition reaction at the a-Br chain end and subsequent chain extension with methyl acrylate.     

室温下甲基丙烯酸甲酯原子转移自由基乳液聚合反应研究

以卤化亚铜（CuX）/1,10-邻二氮菲（phen）配合物为催化剂、2-溴代异丁酸 乙酯（EBiB）为引发剂、十二烷基磺酸钠（SLS）为乳化剂,进行了甲基丙烯酸甲 酯（MMA）的原子转移自由基乳液聚合（ATRP）反应。结果表明,与较高温度（70 - 90 ℃）下的聚合反应相比,室温（25 ℃）时聚合反应有更好的可控性,通过 外加钝化剂的复合催化引发体系CuBr/CuBr_2/phen/EBiB或利用CuCl/phen/EBiB催 化引发体系的“卤素交换反应”,可进一步改善聚合反应的可控性。紫外发光谱测 定结果表明,CuBr/phen配合物在MMA相中的分配倾向随着温度的降低而增大,使得 室温下MMA的乳液ATRP保持了较好的可控性和较快的反应速度。     

Copper(0)‐mediated living radical polymerization of acrylonitrile: SET‐LRP or AGET‐ATRP

Cu(0)‐mediated living radical polymerization was first extended to acrylonitrile (AN) to synthesize polyacrylonitrile with a high molecular weight and a low polydispersity index. This was achieved by using Cu(0)/hexamethylated tris(2‐aminoethyl)amine (Me₆‐TREN) as the catalyst, 2‐bromopropionitrile as the initiator, and dimethyl sulfoxide (DMSO) as the solvent. The reaction was performed under mild reaction conditions at ambient temperature and thus biradical termination reaction was low. The rapid and extensive disproportionation of Cu(I)Br/Me₆‐TREN in DMSO/AN supports a mechanism consistent with a single electron transfer‐living radical polymerization (SET‐LRP) rather than activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). ¹H NMR analysis and chain extension experiment confirm the high chain‐end functionality of the resultant polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Atom‐transfer radical grafting polymerization of 2‐methacryloyloxyethyl phosphorylcholine from silicon wafer surfaces

2‐Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was grafted from silicon wafer surfaces at room temperature by combining self‐assembly of initiator and surface‐initiated atom transfer radical polymerization. Two methods were used to control the grafting process. One was to add free initiator to the reaction system; the other was to add excess deactivator. The grafting densities up to 0.3 chains/nm² were obtained. The surface thickness increased linearly with MPC conversion. The thickness depended on catalyst and monomer concentrations, as well as activator/deactivator ratio. Poly(MPC) layers of >100 nm thick were obtained by optimizing the polymerization conditions. A second block of either poly(MPC) or poly[2‐(dimethylamino)ethyl methacrylate] was also grown from the grafted poly(MPC), demonstrating the system livingness. X‐ray photoelectron spectroscopy was used to examine the surface chemical compositions showed good agreement with the theoretical values. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2931–2942, 2004     

Synthesis and characterization of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐poly(acrylonitrile) via single electron transfer–living radical polymerization process

Preparation of functional fluoromaterials through chemical modification of traditional fluoropolymers has been recognized as an economic and convenient strategy to expand the application areas of fluoropolymers. Poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐polyacrylonitrile (P(VDF‐co‐CTFE)‐g‐PAN) has been successfully synthesized via single electron transfer–living radical polymerization (SET–LRP) process initiated with macroinitiator P(VDF‐co‐CTFE) in the presence of trace amount of Cu(0)/tris(2(dimethylamino)ethyl)amine (Me₆‐TREN) in dimethyl sulfoxide (DMSO) at ambient temperature. The typical side reactions happened on P(VDF‐co‐CTFE) induced by the nitrogen‐containing solvents and high reaction temperature in atom transfer radical polymerization process could be avoided in SET–LRP process by using the mild reaction conditions. Well‐controlled polymerization features were observed under varied reaction conditions including the different reaction temperature, catalyst concentration, as well as monomer amount in feed. An induction period of 0.5–1.0 h in the polymerization procedure was observed at low temperature, which may be attributed to the Cu₂O from the surface of the Cu(0) powder. When Cu(0) catalyst is activated, the introduction period is eliminated. The polymerization rates were decelerated by adding excessive Me₆‐TREN for the formation of more stable CuCl₂/(Me₆‐TREN)₂. The structure of P(VDF‐co‐CTFE)‐g‐PAN was demonstrated by FTIR, NMR, DSC, and TGA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012