Controlled polymerization of methylmethacrylate from fumed SiO2 nanoparticles through atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) is a promising method to synthesize well‐defined polymer/inorganic nanoparticles. However, the surface‐initiated ATRP from commercially mass produced inorganic nanoparticles has seldom been studied. In this study, the surface‐initiated ATRP of methylmethacrylate (MMA) from commercially mass produced fumed silica (SiO₂) nanoparticles was investigated. Unlike the ATRP of MMA initiated from a free initiator, the controllability of ATRP of MMA from the surface of fumed silica nanoparticles was much better using ligand 2,2'‐bipyridine (bpy) than N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) as the initiator was immobilized on the surface of the SiO₂ nanoparticles and the presence of the SiO₂ nanoparticles made the CuCl/bpy catalyst system a homogeneous catalyst system and CuCl/PMDETA a heterogeneous one. The appropriate molar ratio of monomer and initiator was essential for preparing controlled PMMA/SiO₂ nanoparticles. The entire process of ATRP of MMA from the surface of SiO₂ nanoparticles was controllable when using bpy as ligand, xylene as solvent and with a monomer to initiator ratio of 300:1. The ¹H NMR results indicated that the PMMA on the surface of the SiO₂ was prepared via ATRP initiated from 4‐(chloromethyl)phenyltrimethoxysilane. The well‐defined PMMA/SiO₂ nanoparticles obtained have good thermal stability and are well dispersed in organic media as proved by TGA, dynamic light scattering and transmission electron microscopy. © 2013 Society of Chemical Industry     

Reverse atom transfer radical polymerization of acrylonitrile

FeCl₃ coordinated by succinic acid was used as the catalyst for the first time in azobisisobutyronitrile‐initiated reverse atom transfer radical polymerization of acrylonitrile (AN). N,N‐dimethylformamide (DMF) was used as a solvent to improve the solubility of the ligand. A FeCl₃ to succinic acid ratio of 0.5 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. Effects of different solvents on polymerization of AN were also investigated. The rate of the polymerization in DMF is faster than that in propylene carbonate and toluene. The molecular weight of polyacrylonitrile agrees reasonably well with the theoretical molecular weight in DMF. The rate of polymerization increases with increasing the polymerization temperature, and the apparent activation energy was calculated to be 64.8 kJ mol^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 32–36, 2006     

原子转移自由基聚合制备高分子超滤膜技术进展

原子转移自由基聚合(ATRP)是近十几年来发展起来的高效可控/活性聚合新技术。ATRP技术自1995年发现后,将金属催化剂与配位基结合可以控制结构,获得窄分子质量分布。通过ATRP技术在膜表面和膜材料上接枝或嵌段亲水高聚物来制备抗污染、抗菌超滤膜,包括用于生物分离色谱的高效离子交换膜。由于ATRP随反应时间、反应单体和引发剂浓度可以线性控制接枝或嵌段链密度和长度,这使亲水性材料稳定的键合在疏水膜材料上,也有效调控了基膜的孔尺寸和分布,使膜的分离性能有所提高和改善。ATRP技术已成为设计和合成优良新型材料和膜的基础手段。     

原子转移自由基聚合原理及应用

介绍了有关原子转移自由基聚合(ATRP)的聚合原理。最新研究表明:应用ATRP法进行聚合反应可以制备接枝聚合物、嵌段聚合物、超支化聚合物和其它有机/无机混合型聚合物等。ATRP在高分子聚合反应领域具有十分广阔的应用前景。     

ROP和ATRP法制备具有核壳结构的温敏性纳米胶束的研究

结合活性开环聚合(ROP)和原子转移自由基聚合(ATRP)方法,制备了以POSS-OH为核引发剂、PCL为核和PNIPAM为壳的X聚合物纳米胶束。借助GPC,IR,NMR,TEM,UV和DLS对聚合物的分子量、结构、形貌和温敏性进行了分析。结果表明,成功合成了星型嵌段共聚物;当POSS-OH的质量一定时,可以通过[CL]控制POSS-PCL的分子量;纳米胶束具有较为规整的球形和粒径分布均一;纳米胶束具有明显的温敏性与宽的相转变温度。     

The synthesis of CDA-g-PMMA copolymers through atom transfer radical polymerization

Graft copolymer of cellulose diacetate (CDA) and PMMA was synthesized through atom transfer radical polymerization (ATRP). The residual hydroxyl groups on the diacetate cellulose reacted with 2-bromoisobutyryl bromide to yield 2-bromoisobutyryl groups known to be an efficient initiator for ATRP. Then the functional CDA was used as macroinitiator in the ATRP of MMA. The polymerization was carried out in the system of PMDETA/CuBr/1,4-dioxane under 70 °C. Kinetic study indicated that the polymerization is first order. Copolymers were characterized by ¹H NMR and GPC. The molecular weight increased without any trace of the macroinitiator, and the polydispersities were low.     

Nanoscale structure of SAN-PEO-SAN triblock copolymers synthesized by atom transfer radical polymerization

Low molecular weight triblock copolymers (TBCs) with poly(styrene-co-acrylonitrile) (SAN) end-blocks and poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) or polycaprolactone (PCL) mid-blocks were synthesized using atom transfer radical polymerization (ATRP). The influence of molecular weight, composition (mid-block mole fraction), and interaction parameter on the crystallinity and on the formation of an ordered nanoscale phase-separated structure was investigated using thermal analysis, X-ray scattering, and electron microscopy. The TBCs with PEO mole fractions of over 0.5 exhibited PEO crystallinities of around 40% (compared to 72% for the PEO homopolymer) and lamellar nanoscale periodicities of around 176 Å (compared to 143 Å for the PEO homopolymer). The TBCs with PEO, PCL or PPO mole fractions of less than 0.5 exhibited relatively low crystallinities and did not exhibit ordered structures. These results emphasize the importance of the mid-block mole fraction in determining the ability to form an ordered nanoscale structure through mid-block crystallization. The ordered structure disappeared on heating the TBCs above the mid-block melting point, but below the SAN glass transition temperature. The crystallinity was reduced significantly in TBCs that were annealed or cast from a solvent.     

原子转移自由基偶联法合成星形聚合物

以卤端基聚合物为大分子引发剂,卤化亚铜／２,２‘＝二联二吡啶为催化剂,工业二乙烯基苯、纯间－二乙烯基苯、纯对－二乙烯基苯为偶联剂合成了一系列星形聚合物。研究了偶联反应的影响因素。结果表明,反应体系产生凝胶的趋势随着二乙烯基苯与预聚物配比的增加而增加;偶联反应速度随着反应物总浓度的增加而加大;提高反应温度有利于提高偶联效率;以低单体转化率下合成的预聚物为大分子引发剂时的偶联效率高于高单体转化率下合成     

Development of multimodal membrane adsorbers for antibody purification using atom transfer radical polymerization

This contribution describes a graft polymerization strategy to prepare multimodal membranes, a new class of high-productivity adsorptive materials for the purification of therapeutic proteins. Surface-initiated atom transfer radical polymerization was used to graft poly(glycidyl methacrylate) ‘tentacles’ from the pore surfaces of macroporous regenerated cellulose membranes. Subsequently, 4-mercaptobenzoic acid was coupled to the membranes by an epoxide ring-opening reaction. ATR-FTIR measurements support successful ligand incorporation. Graft polymerization studies from cellulose-coated silicon substrates were done in parallel to measure the thickness evolution of the polymer coating, which plays an important role on protein binding capacities. Protein binding experiments with bovine immunoglobulin G show that the multimodal membranes have high equilibrium capacities, up to 150 mg IgG/mL. The binding capacities are pH-dependent, with maximum binding at pH near the protein isoelectric point. Characteristic of multimodal adsorbers, the membranes retain about 70% of their equilibrium binding capacity at moderate ionic strength (300 mM) and about 40% at high ionic strength (1.6 M).     

原子转移自由基聚合法合成PS-g-PMMA

以氯乙酰化聚苯乙烯微球（PS-acyl-Cl）为大分子引发剂,甲基丙烯酸甲酯（MMA）为单体,CuCl/CuCl₂及N,N,N′,N′-四甲基乙二胺（TMEDA）为催化体系的原子转移自由基聚合反应,成功在PS-acyl-Cl表面接枝上PMMA分子链而获得聚苯乙烯 接枝 聚甲基丙烯酸甲酯（PS-g-PMMA）。考察了催化剂、反应温度、溶剂用量等条件对接枝反应的影响,优化的反应条件下,使用氯乙酰基担载量3.44 mmol.g^-1的PS-acyl-Cl,15 h可获得增重率687% 的PS-g-PMMA,且反应表现出一级动力学特征（k=513×10^-5 s^-1）。通过改变反应条件,可得到不同PMMA接枝链长的PS-g-PMMA。反应得到的PS-g-PMMA经水解后有望作为高担载量弱酸型离子交换树脂或进一步功能化后作为酶的柔性固定化载体。     

反向原子转移自由基聚合研究进展

原子转移自由基聚合是一种新兴的活性/可控聚合方法,而反向ATRP又是在传统ATRP方法基础上衍生出的一种摒弃ATRP方法中一些缺点的新生活性聚合方法。文中介绍了反向ATRP的建立原理,从单体、引发剂、催化体系等方面综述了反向ATRP的研究进展。     

原子转移自由基聚合机理及其应用

原子转移自由基聚合(ATRP)是目前研究的热点之一。该文介绍了ATRP的反应机理及其应用。     

Bioactive surfaces and biomaterials via atom transfer radical polymerization

Recent progress in controlled radical polymerizations, in particular atom transfer radical polymerization (ATRP), has provided a unique means for the design and synthesis of bioactive surfaces and functional biomaterials. This review summarizes such recent research activities. The synthesis strategies of bioactive surfaces and biomaterials via ATRP are described in detail. The highly robust and versatile ATRP technique is particularly suited for the preparation of functional bioactive surfaces, including antifouling, antibacterial, stimuli-responsive, biomolecule-coupled and micropatterned surfaces. In addition to bioactive surfaces, ATRP has also been widely used for the preparation of well-structured functional biomaterials, such as micellar delivery systems, hydrogels, cationic gene carriers and polymer–protein conjugates. The research activities in the last decade indicate that ATRP has become an essential tool for the design and synthesis of advanced, noble and novel biomaterials.     

m－DVB和p－DVB原子转移自由基聚合动力学

以氯端基聚苯乙烯为大分子引发剂,氯化亚铜／２,２’－联二吡喧为催化剂,邻二甲苯为溶剂,用气相色谱分别研究了对二乙烯基苯（ｐ－ＤＶＢ）和间二乙烯在苯（ｍ－ＤＶＢ）在１００￣１３０℃的原子转移自由基聚合动力学。结果表明,聚合符合表观一级反应动力学。ｐ－ＤＶＢ在１００,１１０,１２０、１３０℃的聚合速率常数分别为０．０７２,０．１２８,０．３７９,０．５４６ｈ＾－１,ｍ－ＤＶＢ在上述不同温度的聚合速率常     

原子转移自由基法合成乙丙橡胶接枝物中的热聚合研究

采用原子转移自由基聚合法(ATRP)合成了三元乙丙橡胶与苯乙烯的接枝共聚物(EPDM-g-St),动力学研究表明聚合过程为“活性”聚合。在接枝聚合过程中发现了明显的苯乙烯热聚合现象。对接枝聚合中得到的均聚苯乙烯进行表征的结果表明,苯乙烯在ATRP接枝体系中的热聚合过程在一定程度上受到ATRP机理的控制;升高温度和延长反应时间使得热聚合更为显著。     

丙烯酸酯原子转移自由基聚合多官能引发剂

分别用乙二醇和三羟甲基丙烷与二氯乙酰氯反应合成了双(二氯乙酸)乙二醇酯和三羟甲基丙烷三(二氯乙酸酯),通过测定它们与单官能团引发剂2-氯乙酸乙酯共同引发的丙烯酸酯原子转移自由基聚合所得聚合物的相对分子质量和相对分子质量分布,证明它们分别是丙烯酸酯原子转移自由基聚合的四官能团和六官能团引发剂.     

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.     

聚丙烯的原子转移自由基接枝共聚

将商品氯化聚丙烯还原后作为原子转移自由基聚合的引发剂,在溴化铜/2,2'－联吡啶的催化下与聚苯乙烯接枝共聚.核磁共振氢谱分析结果表明聚丙烯与聚苯乙烯发生了接枝共聚;接枝率随聚合时间的增加而增大.     

Preparation of hyperbranched polymers by atom transfer radical polymerization

A cheap acrylic AB* monomer, 2‐(2‐chloroacetyloxy)‐isopropyl acrylate (CAIPA), was prepared from 2‐hydroxyisopropyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self‐condensing vinyl polymerization by atom transfer radical polymerization (ATRP), a “living”/controlled radical polymerization, has yielded hyperbranched polymers. All the polymerization products were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR). CAIPA exhibited distinctive polymerization behavior that is similar to a classical step‐growth polymerization in the relationship of molecular weight to polymerization time, especially during the initial stage of the polymerization. However, a significant amount of monomer remained present throughout the polymerization, which is consistent with typical chain polymerization. Also, if a much longer polymerization time was used, the polymer became gel. As a result of the unequal reactivity of group A* and B*, the polymerization is different from an ideal self‐condensing vinyl polymerization: the branch structures of polymers prepared depend dramatically on the ratio of 2,2'‐bipyridyl to CAIPA. Hyperbranched polymers exhibit improved solubility in organic solvent, however, they have lower thermal stability than their linear analogs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2114–2123, 2002     

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.