单电子转移-蜕化链转移活性自由基细乳液聚合制备PS-b-PBA-b-PS共聚物

以碘仿为引发剂、连二亚硫酸钠/碳酸氢钠为催化体系、十二烷基硫酸钠/十六烷为乳化体系,通过单电子转移-蜕化链转移（SET-DT）活性自由基细乳液聚合合成碘端基化聚丙烯酸丁酯（I-PBA-I）,进而以其为大分子引发剂引发苯乙烯聚合,制备聚苯乙烯-b-聚丙烯酸丁酯-b-聚苯乙烯（PS-b-PBA-b-PS）三嵌段共聚物,并进行共聚物结构和性能表征。发现两个阶段的SET-DT细乳液聚合均具有大的反应速率,碘仿引发剂用量少,可获得高分子量PBA和PS-b-PBA-b-PS共聚物。PS-b-PBA-b-PS共聚物具有微相分离和热塑性弹性体特征,PS质量分数为50%的嵌段共聚物的拉伸强度达9.8 MPa,断裂伸长率为660%。     

单电子转移活性自由基聚合制备星形丙烯酰胺-对苯乙烯磺酸钠共聚物

以丙烯酰胺(AM)和对苯乙烯磺酸钠(SSS)为单体,四氯化碳(CCl_4)为引发剂,以铜粉/三(N,N-二甲基氨基乙基)胺(Cu~0/Me_6-TREN)为催化剂,采用单电子转移活性自由基聚合(SET-LRP)方法,在25℃水溶液中制备了四臂星形二元共聚物P(AM-SSS)。采用红外光谱法、核磁共振对合成的共聚物进行分析表征,并考察了催化体系用量、引发剂用量、引发温度及功能单体AM与SSS的用量等因素对聚合物黏均分子量M_η的影响,同时测定了不同浓度盐溶液中聚合物溶液的表观黏度。结果表明:在引发温度25℃、单体AM与SSS的摩尔比为680:20、引发剂质量分数0.068%、催化体系占单体的质量分数为0.7%的条件下,所得聚合物产品相对分子质量最高,达到176万,聚合反应产率最高可达89%;此外,与Mg~(2+)相比,Na~+对该聚丙烯酰胺表观黏度的影响更为显著。     

功能性甲基丙烯酸甲酯-甲基丙烯酸缩水甘油酯嵌段聚合物ATRP合成

以2-溴代丙酸乙酯(EPN-Br)为引发剂,CuCl和2,2’-联二吡啶(BPY)为催化剂,以甲基丙烯酸甲酯(MMA)为原料,用原子转移自由基(ATRP)的方法,在80℃下合成带有卤原子的聚甲基丙烯酸甲酯大分子引发剂,在20～50℃下,以丁酮和正丙醇的混合液为溶剂,引发甲基丙烯酸缩水甘油酯(GMA)聚合,制得侧链含有环氧基团的PMMA-b-PGMA嵌段共聚物,分子量分布较窄,聚合物的分子量可通过单体与引发剂的比例进行控制。     

Particle growth behavior of poly(methyl methacrylate) nanoparticles synthesized by the reversible addition fragmentation transfer living radical polymerization reaction

PMMA nanoparticles with highly mono‐dispersed size distribution were prepared using the RAFT living radical emulsion polymerization technique. A novel sur‐iniferter for the RAFT reaction, DTBA, was synthesized and its chemical structure was identified using several spectroscopic techniques. The relationship between the particle size and the molecular weight of the polymer was investigated measuring the rate of growth of each during formation of particles, and was well explained by the simple random flight molecular conformation model. The particle size increased up to a certain value with decreasing sur‐iniferter concentration and then leveled off, because the surface charge density of the growing particles was not high enough to stabilize the particles in aqueous medium above that value. The core‐shell type di‐block copolymer nanoparticles were also successfully prepared via RAFT reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Atom transfer radical coupling of polystyrene and poly(methyl acrylate) synthesized by reverse iodine transfer polymerization

Iodo-terminated polystyrene and poly(methyl acrylate) (PMA-I) were synthesized by reverse iodine transfer polymerization. The resulting polymers were coupled by atom transfer radical coupling using Cu(I)/linear amino-ligand catalysts in the presence of reducing Cu(0). The efficiency of the coupling reaction is discussed as a function of various factors, namely, the Cu(0) particle sizes, the number of nitrogen present in the ligand structure, the type of halogen associated with Cu(I) (CuX, X = I, Br, Cl), the nature of the polymer and the nature of the chain ends. In particular, a quantitative coupling (100%) was obtained with a CuBr/HMTETA system in the presence of nanosized Cu(0) for PMA-I, thus opening for the first time a facile route to telechelic and multiblock poly(acrylate)-based structures.     

Effects of reaction conditions on poly(methyl methacrylate) polymerized by living radical polymerization with iniferter

Living radical polymerization of methyl methacrylate (MMA) through the use of benzyl diethyl dithiocarbamate (BDC) was studied. The aim was to investigate the role of the concentration, BDC‐to‐MMA mol ratio, and reaction time upon the molecular weight, polydispersity, and conversion of the product. It was found that the molecular weight and the conversion increase with increase of the concentration at the expense of low polydispersity. The reaction time also played a significant role, especially at a relatively long reaction time where molecular weight, polydispersity, and conversion increased with increasing reaction time. In terms of the mol ratio effect, it was found that there was a critical mol ratio for maximum conversion. The results indicate that the kinetics of polymerization of MMA through the use of a BDC inifeter is different from that in the presence of a conventional initiator. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 938–944, 2000     

CuBr2/Me6TREN-mediated living radical polymerization of methyl methacrylate at ambient temperature

A universal nitrogen based ligand, tris[2-(dimethylamino) ethyl] amine (Me₆TREN), was firstly employed as both reducing agent and ligand for atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP) of methyl methacrylate (MMA) in bulk and solution, using CuBr₂ as the catalyst and 2-bromoisobutyrate as the initiator. Remarkably high activity catalytic system (CuBr₂/Me₆TREN) enabled the ambient temperature polymerization and thus biradical termination reactions were low. The polymerization exhibited typical living radical polymerization features, including pseudo first-order kinetics of polymerization, linear increase in the molecular weight versus monomer conversion, and low polydispersity index values. Moreover, effects of solvent and reaction temperature on the polymerization were investigated in detail. The rate of polymerization increased with reaction temperature and the apparent activation energy of the polymerization was calculated to be 51.11 kJ/mol. Gel permeation chromatography and ¹H NMR analyses as well as chain extension experiment confirmed the living chain-end functionality.     

Atom transfer radical polymerization of methyl acrylate from a multifunctional initiator at ambient temperature

A multifunctional initiator for ATRP has been synthesized by reacting a hyperbranched polyether, based on 3-ethyl-3-(hydroxymethyl)oxetane, with 2-bromo-isobutyrylbromide. The macroinitiator contained approximately 25 initiating sites per molecule. It was used for the atom transfer radical polymerization of methyl acrylate mediated by Cu(I)Br and tris(2-(dimethylamino)ethyl)amine (Me₆-TREN) in ethyl acetate at room temperature. This yielded a co-polymer with a dendritic-linear architecture. The large number of growing chains from each macromolecule increases the probability of inter-and intramolecular reactions. In order to control these kinds of polymerizing systems and prevent them from forming a gel, the concentration of propagating radicals must be kept low. The polymerizations under these conditions were well controlled. When a ratio of initiating sites-to-catalyst of 1:0.05 was used, the polymers from all of the reactions had a low polydispersity, ranging from 1.1 to 1.4. None of the polymerizations under these conditions gave gelation. Monomer conversions as high as 65% were reached while maintaining control over the polymerization.     

Long-lived cation radical formation of aromatic amines in poly(methyl methacrylate) matrix at room temperature by two-photon excitation

Summary Melt drawn fibres of poly(ether-ether-ketone) (PEEK) have been investigated in which various textural effects occur, arising through alignment of self-seeding nuclei, rather than simple orientation on a molecular level. Growth of the seeds can be arrested at different stages, with associated changes in x-ray diffraction patterns.     

Atom transfer radical polymerization of methyl methacrylate initiated with a macroinitiator of poly(vinyl acetate)

Well‐defined poly(vinyl acetate‐b‐methyl methacrylate) block copolymers were successfully synthesized by the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in p‐xylene with CuBr as a catalyst, 2,2′‐bipyridine as a ligand, and trichloromethyl‐end‐grouped poly(vinyl acetate) (PVAc–CCl₃) as a macroinitiator that was prepared via the telomerization of vinyl acetate with chloroform as a telogen. The block copolymers were characterized with gel permeation chromatography, Fourier transform infrared, and ¹H‐NMR. The effects of the solvent and temperature on ATRP of MMA were studied. The control over a large range of molecular weights was investigated with a high [MMA]/[PVAc–CCl₃] ratio for potential industry applications. In addition, the mechanism of the polymerization was discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1089–1094, 2006     

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。     

Compatibilization of poly(methyl acrylate) with poly(methyl methacrylate) through charge transfer interactions

Summary Copolymers of methyl acrylate (MA) with an electron-donor comonomer (N-vinylcarbazole) (NVC) are mixed with copolymers of methyl methacrylate (MMA) with a electron-acceptor comonomer (2-(3,5-dinitrobenzoyl) oxyethyl methacrylate) (DNBM) such that 1:1 mol ratios of NVC:DNBM are present at all times. The blends obtained are phase separated up to an average of 27 mol% donor/acceptor structural unit in the copolymer. Above 27 mol% perturbation, poly(MA) and poly(MMA) become compatible.     

Quickly self-healing hydrogel at room temperature with high conductivity synthesized through simple free radical polymerization

The use of conductive self-healing hydrogels in electronic devices not only reduces replacement and maintenance costs but also prolongs their lifetime. Therefore, developing hydrogels with autonomous self-healing properties and electronic conductivity is vital for the advancement of emerging fields, such as conductors, semiconductors, sensors, artificial skin, and electrodes and solar cells. However, it remains a challenge to fabricate a hydrogel with high conductivity that can be healed quickly at room temperature without any external stimulus. In this work, we report an effective and simple free radical polymerization approach to synthesizing a hydrogel using modified rGO and acrylate monomers containing abundant ion groups. The hydrogel exhibits excellent electronic conductivity, extremely fast electronic self-healing ability, and excellent repeatable restoration performance at 25 °C. The conductivity of the hydrogel reaches 27.2 S/m, the hydrogel recovers its original shape, and scoring scratched on the surface totally disappears after holding at 25 °C for 40 s. This conductive, room-temperature self-healing hydrogel takes unique advantage of supramolecular chemistry and polymer nanoscience and has potential applications in various fields such as self-healing electronics, artificial skin, soft robotics, biomimetic prostheses, and energy storage. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47379.     

High molecular weight poly(methyl alkyl fumarates): radical high polymerization of methyl alkyl fumarates and monomer-isomerization radical polymerization of methyl alkyl maleates

Summary High molecular weight poly(methyl alkyl fumarate) were prepared through radical polymerization of methyl alkyl fumarates(MRF) and monomer-isomerization radical polymerization of methyl alkyl maleates(MRM). The polymerization reactivities(yield and viscosity) of MRFs and MRMs were found to increase with increasing of the bulkiness of the ester alkyl substituents, but MRFs showed generally higher reactivities than MRMs. These polymers were also observed to consist of less- or non-flexible rod-like poly(methoxy-carbonylmethylene-alt-alkoxycarbonylmethylene) structure depending on their bulkiness. The MtBF polymer did not melt, which showed somewhat decreased thermal stability.Polymers from 1,2-Disubstituted Ethylenic Monomers. VIII.     

Functionalization of chitosan via single electron transfer living radical polymerization in an ionic liquid and its antimicrobial activity

In this work, single electron transfer living radical polymerization (SET‐LRP) was used to functionalize chitosan in a well‐controlled manner. The chitosan‐based macroinitiator was first synthesized and then initiated the SET‐LRP of methacryloyloxyethyl trimethylammonium chloride (DMC) in ionic liquid system, using Cu⁰/N,N,N′,N′,N′′‐pentamethyldiethylenetriamine as a catalyst. The grafting of PDMC brushes on chitosan was confirmed and analyzed by Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance. Transmission electron microscopy reveals that the chitosan copolymer showed self‐assembled behavior in acetone. Surface properties of the copolymer have been investigated by environment scanning electron microscopy analysis. The linear relationship between the ln([M]₀/[M]_t) and time, the linear increase of number‐average molecular mass with conversion as well as the low polydispersity index of the polymer confirmed the “living/controlled” features of the polymerization of DMC through SET‐LRP. Finally, the chitosan copolymer demonstrates its potential antibacterial application, showing excellent inhibitive capability against Escherichia coli. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42754.     

Well-defined poly(methyl methacrylate) grafted to polyethylene with reverse atom transfer radical polymerization initiated by peroxides

A reverse atom transfer radical polymerization (ATRP) with FeCl₃/PPh₃/peroxides was applied to grafting of methyl methacrylate (MMA) to polyethylene (PE). Peroxides on PE were generated by γ-ray irradiation in air. A reverse ATRP of methyl methacrylate with benzoyl peroxide, cumene hydroperoxide, and di-t-butyl peroxide as models of the PE peroxides was confirmed to proceed successfully in living fashion. In an inhomogeneous (bulk) grafting system, the grafting ratio (GR) of PMMA to PE weights, molecular weight (M_n) and its distribution of grafted PMMA were not controlled with time, i.e. the grafting of MMA with a reverse ATRP to the oxidized PE failed in well-defined grafting. On the other hand, a homogeneous (in o-xylene solution) grafting system provided a well-controlled M_n, narrow polydispersity of grafted PMMA and a linear relation between M_n and GR, indicating a controlled grafting. The controlled grafting with a reverse ATRP combined to a radiation-induced grafting was achieved successfully. The grafting of MMA to polypropylene in this way also seemed to be controlled well.     

Novel poly(methyl methacrylate)‐block‐polyurethane‐block‐poly(methyl methacrylate) tri‐block copolymers through atom transfer radical polymerization

Poly(methyl methacrylate)‐block‐polyurethane‐block‐poly(methyl methacrylate) tri‐block copolymers have been synthesized successfully through atom transfer radical polymerization of methyl methacrylate using telechelic bromo‐terminated polyurethane/CuBr/N,N,N,N″,N″‐pentamethyldiethylenetriamine initiating system. As the time increases, the number‐average molecular weight increases linearly from 6400 to 37,000. This shows that the poly methyl methacrylate blocks were attached to polyurethane block. As the polymerization time increases, both conversion and molecular weight increased and the molecular weight increases linearly with increasing conversion. These results indicate that the formation of the tri‐block copolymers was through atom transfer radical polymerization mechanism. Proton nuclear magnetic resonance spectral results of the triblock copolymers show that the molar ratio between polyurethane and poly (methyl methacrylate) blocks is in the range of 1 : 16.3 to 1 : 449.4. Differential scanning calorimetry results show T_g of the soft segment at ?35°C and T_g of the hard segment at 75°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

原子转移自由基聚合合成支化聚丙烯腈

以二乙烯苯为支化单体,α-溴代异丁酸叔丁酯为引发剂,CuBr和2,2'-联吡啶为催化体系,利用本体和溶液原子转移自由基聚合合成了支化聚丙烯腈.采用核磁共振谱仪、凝胶渗透色谱仪和多角度激光光散射仪等测试了聚合物结构、相对分子质量及其分布.用无水乙酸钠对支化聚丙烯腈进行末端改性,得到了在硫氰酸钠水溶液中性能稳定、可长期保存的支化聚丙烯腈,而改性对聚合物的耐热性能没有影响.     

用聚合转化法合成聚异丁烯-聚丙烯酸叔丁酯嵌段聚合物

使用BCl3/CH2Cl2/DTBP/IB反应体系实现了异丁烯的正离子聚合,得到末端为硼氧烷基的聚异丁烯,其与苯基溴化镁发生金属转移反应,生成末端为二苯基硼烷的聚异丁烯,其在常温下与氧气发生氧化反应,生成碳氧自由基,从而引发丙烯酸叔丁酯的自由基聚合,得到异丁烯和丙烯酸叔丁酯的嵌段聚合物.     

活性自由基聚合研究的新动态──可逆加成-断裂链转移自由基聚合

介绍了基于可逆链转移思想的“活性”／控制自由基聚合。着重介绍澳大利亚Ｒｉｚｚａｒｄｏ研究小组的最新研究成果：以双硫酯类化合物为链转移剂的可逆加成－断裂链转移自由基聚合。分析其活性特征,并阐明其反应机理