Pseudohalogens in atom transfer radical polymerization of methyl methacrylate

In recent advances in controlled radical polymerization, atom transfer radical polymerization (ATRP) has achieved increasing interest. This investigation reports the ATRP of methyl methacrylate (MMA) using pseudohalogens as initiator as well as an anion for copper catalyst. The results were compared with the conventional halide system. Different pseudohalides were used as the initiator for the ATRP of MMA in combination with CuX (X = pseudohalide or halide) as the catalyst. Pseudohalide initiator in combination with Cu(halide) catalyst leads to inefficient ATRP due to slow initiation. Pseudohalide initiator in combination with Cu(pseudohalide) catalyst leads to uncontrolled or no polymerization. The polymers were characterized by using GPC, IR, MALDI‐TOF‐MS, and TGA analysis. IR and MALDI analysis showed that the resultant polymer had pseudohalide as the end group. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3857–3864, 2007     

Emulsion atom transfer radical polymerization of 2-ethylhexyl methacrylate

The emulsion atom transfer radical polymerization (ATRP) of 2-ethylhexyl methacrylate (EHMA) was carried out with ethyl 2-bromoisobutyrate (EBiB) as an initiator and copper bromide (CuBr)/4,4′-dinonyl-2,2′-bipyridyl (dNbpy) as a catalyst system. The effects of surfactant type and concentration, temperature, monomer/initiator ratio, and CuBr₂ addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the polymerization systems with Tween 80 and Brij 98 as surfactants at 30 °C gave the best latex stability. The polymer samples prepared under these conditions had narrow molecular weight distributions (M_w/M_n=1.1-1.2) and linear relationships of number-average molecular weight versus monomer conversion.     

原子转移自由基聚合催化体系的研究进展

采用原子转移自由基聚合(ATRP)、反相ATRP(R-ATRP)可以对聚合物进行分子设计,制备结构和相对分子质量可控的均聚物、嵌段共聚物、接枝和梳状聚合物以及星形和一些高支化的聚合物.该类反应中,催化体系是研究的重点和热点.着重介绍了ATRP和R-ATRP聚合催化体系的研究进展,并且针对其催化剂脱除困难的问题,介绍了催化剂分离方面的最新研究进展.     

原子转移自由基聚合负载化催化剂研究进展

综述了几种原子转移自由基聚合(ATRP)用负载化催化体系的组成及应用,主要包括硅胶或石英、交联聚苯乙烯或其它聚合物为载体进行的催化剂负载化,它们都能够部分解决催化剂残留问题,但却有一定的局限性;负载/可溶性混杂催化体系成为解决这一问题的新方法,而且它与传统的均相催化体系相比,可控性没有明显差异,有希望作为未来解决催化剂残留的有效方法.最后展望了ATRP负载化催化荆的发展方向.     

Silica-supported quinine-CuBr catalyzed atom transfer radical polymerization of methyl methacrylate

9-Amino epi-quinine was used as a ligand in the atom transfer radical polymerization (ATRP) for the first time, and high monomer conversion as well as small polydispersity could be obtained. The 9-amino epi-quinine-containing organosilane was synthesized and immobilized onto three different silica supports, i.e., fumed SiO₂, SBA-15, and MCM-48, followed by complexing with CuBr. With the MCM-48 supported catalyst, polymerization of methyl methacrylate achieved high monomer conversion, small polydispersity, and low residual copper content in the product. This heterogeneous catalyst could also be recycled effectively.     

Reverse atom transfer radical polymerization of methyl methacrylate in different solvents

The reverse atom transfer radical polymerization of methyl methacrylate was investigated in different solvents: xylene, N,N‐dimethylformamide, and pyridine. The polymerizations were uncontrolled, using 2,2′‐bipyridine as a ligand in xylene and pyridine because the catalyst (CuBr₂/2,2′‐bipyridine complex) had poor solubility in the xylene system. In the pyridine system, the solubility of the catalyst increased, but the solvent could complex with CuBr₂, which influenced the control of the polymerization. In the N,N‐dimethylformamide system, the catalyst could be dissolved in the solvent completely, but the ? N(CH₃)₂ group in N,N‐dimethylformamide could also complex with CuBr₂, so the polymerization could not be well controlled. The ligand of 4,4′‐di(5‐nonyl)‐2,2′‐bipyridine was also investigated in xylene; the introduction of the ? CH(C₄H₉)₂ group enabled the CuBr₂/4,4′‐di(5‐nonyl)‐2,2′‐bipyridine complex to easily dissolve in xylene, and the polymerizations were well controlled. The number‐average molecular weight increased linearly with the monomer conversion from 4280 to 14,700. During the whole polymerization, the polydispersities were quite low (1.07–1.10). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Surface-initiated atom transfer radical polymerization of methyl methacrylate on magnetite nanoparticles

The synthesis of magnetite nanoparticles coated with a well-defined graft polymer is reported. The magnetite nanoparticles with an initiator group for copper-mediated atom transfer radical polymerization (ATRP), 2-(4-chlorosulfonylphenyl) ethyltrichlorosilane (CTCS) chemically bound on their surfaces were prepared by the self-assembled monolayer-deposition method. The surface-initiated ATRP of methyl methacrylate (MMA) was carried out with the CTCS-coated magnetite nanoparticles in the presence of free (sacrificing) initiator, p-toluenesulfonyl chloride. Polymerization proceeded in a living fashion, exhibiting first-order kinetics of monomer consumption and a proportional relationship between molecular weight of the graft polymer and monomer conversion, thus providing well-defined, low-polydispersity graft polymers with an approximate graft density of 0.7 chains/nm². The molecular weight and polydispersity of the graft polymer were nearly equal to those of the free polymer produced in the solution, meaning that the free polymer is a good measure of the characteristics of the graft polymer. The graft polymer possessed exceptionally high stability and remarkably improved dispersibility of the magnetite nanoparticles in organic solvent.     

原子转移自由基聚合中过渡金属催化剂的研究进展

综述了正向、反向原子转移自由基聚合(ATRP)中不同种类过渡金属催化剂的特点和进展以及配体对催化剂催化活性和选择性的影响。     

原子转移自由基聚合最新研究进展

概述了原子转移自由基聚合（ATRP）在引发体系、反应温度、反应介质、实施方法等方面的进展；介绍了3种不同催化剂脱除技术；结合最新的研究成果，着重论述了ATRP在进行聚合物分子设计，制备窄分子量分布聚合物、无规、梯度和交替共聚物，嵌段共聚物，末端官能团聚合物，接枝和梳状聚合物，星型及高支化聚合物等方面的应用。     

Reverse atom transfer radical polymerization of methyl methacrylate in imidazolium ionic liquids

Reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) employing 2,2-azobisisobutyronitrile (AIBN)/CuCl₂/bipyridine(bipy) as the initiating system was approached at 80 °C in two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄mim][BF₄]) and 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C₁₂mim][BF₄]), respectively. The polymerization in [C₁₂mim][BF₄] proceeded in a well-controlled manner as evidenced by kinetic studies, end group analysis, chain extension, and block copolymerization results, but not in [C₄mim][BF₄] presumably due to poor solubility of PMMA in it. The kinetic study of reverse ATRP of MMA in recycled [C₁₂mim][BF₄] suggested that this ionic liquid could be re-used as reaction solvent after simple purification, without affecting the living nature of polymerization.     

甲基丙烯酸甲酯的反向原子转移自由基沉淀聚合反应的研究

以甲基丙烯酸甲酯（MMA）为单体,偶氮二异丁腈（AIBN）为引发剂,以氯化铜（CuCl2）/2,4,6-三（二甲氨基甲基）苯酚（DMP-30）为催化体系,以乙醇为溶剂,进行了甲基丙烯酸甲酯的反向原子转移自由基沉淀聚合。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。     

电子转移生成催化剂的原子转移自由基聚合研究进展

通过分析传统ATRP(原子转移自由基聚合)体系的不足之处,指出在原有ATRP的基础上引入的电子转移技术[即电子转移生成催化剂的ATRP(AGET ATRP)]的必要性。概括了AGET ATRP的类型[包括电子转移活化再生催化剂引发的ATRP(ARGET ATRP)、活化剂连续再生引发剂引发的ATRP(ICAR ATRP)、生物还原剂还原的ATRP、电化学介导的ATRP(eATRP)和终极ATRP(Ultimate ATRP)等],并讨论了AGET ATRP的影响因素、过程机制。最后对AGET ATRP的研究方面进行了展望。     

Kinetic study of atom transfer radical polymerization of methyl methacrylate in ionic liquids

The kinetics of methyl methacrylate (MMA) homopolymerization performed by atom transfer radical polymerization (ATRP) is investigated in detail using ethyl‐2‐bromopropionate (EPN‐Br) as initiator, CuBr as catalyst, and pentamethyldiethylenetriamine (PMDETA) as ligand in ionic liquids (ILs) and acetonitrile. ILs in this research covered two different substitutional imidazolium cations and anions including halogen and halogen‐free ones. The typical cations include 1‐butyl‐3‐methylimidazolium, 1‐ethyl‐3‐methylimidazolium and the typical anions include bromide, tetrafluoroborate. The effects of solvents, temperature, and reaction ingredients ratios on the polymerization kinetics are all investigated in this article and the apparent energy of activation (ΔE) calculated for the ATRP of MMA in 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate is 6.95 KJ/mol. The number‐average molecular weights (M_n) increase linearly with conversion but are much higher than the theoretical values. It is probably due to the low concentration of deactivator at the early stage of polymerization and the lower bond energy of C‐Br in PMMA‐Br than that in EPN‐Br. Moreover, the catalyst is easily separated from the polymer and the regenerated catalyst is reused for more than three times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Pyridylphosphine ligands for iron-based atom transfer radical polymerization of methyl methacrylate and styrene

Two pyridylphosphine ligands, 2-(diphenylphosphino)pyridine (DPPP) and 2-[(diphenylphosphino)methyl]pyridine (DPPMP), were investigated as complexing ligands in the iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and styrene with various initiators and solvents. In studies of their ATRP behavior, the FeBr₂/DPPP catalytic system was a more efficient ATRP catalyst for the MMA polymerization than the other complexes studied in this paper. Most of these systems were well controlled with a linear increase in the number-average molecular weights (M_n) vs. conversion and relatively low molecular weight distributions (M_w/M_n = 1.15-1.3) being observed throughout the reactions, and the measured molecular weights matched the predicted values with the DPPP ligand. The polymerization rate of MMA attained a maximum at a ratio of ligand to metal of 2:1 in p-xylene at 80 °C. The polymerization was faster in polar solvents than in p-xylene. The 2-bromopropionitrile (BPN) initiated ATRP of MMA with the FeX₂/DPPP catalytic system (X = Cl, Br) was able to be controlled in p-xylene at 80 °C. The polymerization of styrene was able to be controlled using the PECl/FeCl₂/DPPP system in DMF at 110 °C.     

Efficiency of ligands in atom transfer radical polymerization of lauryl methacrylate and block copolymerization with methyl methacrylate

Atom transfer radical polymerization of lauryl methacrylate (LMA) was carried out in the presence of various ligands using ethyl-2-bromoisobutyrate as initiator and CuBr as catalyst in toluene at 95 °C. The ligands used were 2,2′-bipyridyl,4,4′-dimethyl-2,2′-bipyridyl, N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA) and N-(n-propyl)-2-pyridylmethanimine (PPMI). Controlled polymerization was observed with PMDETA and PPMI ligands and poly(LMA)s with narrow molecular weight distribution (MWD) (M_w/M_n≤1.2) were obtained. The first-order time-conversion plot showed the presence of termination in the presence of PMDETA. A linear first-order time-conversion plot with a small induction period (∼10 min) was observed in the presence of PPMI ligand. Di-block copolymers of LMA and methylmethacrylate with controlled molecular weight and narrow MWDs were synthesized via sequential monomer addition.     

An efficient,heterogeneous, reusable atom transfer radical polymerization catalyst

Melamine based porous polymer (MPP) was prepared as a template solid to incorporate Cu(I) cations into the framework through chelating with nitrogen groups of the melamine. The copper integrated porous material (Cu(I)@MPP) was used as a heterogeneous catalyst and displayed high activity in copper catalyzed atom transfer radical polymerization of methyl methacrylate. The characterization of the Cu(I)@MPP was performed using nitrogen adsorption experiments and wide‐angle X‐ray and Fourier transform infrared spectroscopies. The atomic absorption spectroscopy measurements confirmed that the catalyst is practically non‐leaching and Cu(I) was found to be below 20 ppb after each atom transfer radical polymerization. Moreover, the catalyst showed reusability without any significant change in its activity. © 2017 Society of Chemical Industry     

High-pressure atom transfer radical polymerization of methyl methacrylate for well-defined ultrahigh molecular-weight polymers

The feasibility of high-pressure atom transfer radical polymerization (ATRP) for synthesizing well-defined polymers of extraordinarily high molecular weights was demonstrated. ATRP of methyl methacrylate (MMA) under pressures up to 500 MPa was investigated at 60 °C. The addition of a small amount of a Cu(II)Cl₂/ligand complex along with the general benefits of high pressure of enhancing propagation and suppressing termination brought about an excellent control of polymerization even with an extremely low concentration of ATRP initiator. For example, there was produced PMMA with a number-average molecular weight M_n of 3.6 × 10⁶ and a polydispersity index of 1.24, which had never been achieved by conventional ATRP.     

Studies on atom transfer radical emulsion polymerization of n‐butyl methacrylate

Atom transfer radical polymerization (ATRP) of n‐butyl methacrylate (BMA) in water‐borne media, catalyzed and initiated by CuCl/4,4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) and Ethyl 2‐bromopropinate (BrCH₃CHCOOC₂H₅₎ was conducted. The influence of several factors, such as the amount of surfactant, catalyst, initiator and the reaction time, temperature on the stability of the latexes and the control of the polymerization was investigated. The nucleation mechanism of the latexes, thermodynamic data and activation parameters for the ATRP emulsion polymerization of BMA were also reported. POLYM. ENG. SCI. 45:297–302, 2005. © 2005 Society of Plastics Engineers.