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     

Telechelic polymers by living and controlled/living polymerization methods

Telechelic polymers, defined as macromolecules that contain two reactive end groups, are used as cross-linkers, chain extenders, and important building blocks for various macromolecular structures, including block and graft copolymers, star, hyperbranched or dendritic polymers. This review article describes the general techniques for the preparation of telechelic polymers by living and controlled/living polymerization methods; namely atom transfer radical polymerization, nitroxide mediated radical polymerization, reversible addition-fragmentation chain transfer polymerization, iniferters, iodine transfer polymerization, cobalt mediated radical polymerization, organotellurium-, organostibine-, organobismuthine-mediated living radical polymerization, living anionic polymerization, living cationic polymerization, and ring opening metathesis polymerization. The efficient click reactions for the synthesis of telechelic polymers are also presented.     

Polymer vectors via controlled/living radical polymerization for gene delivery

The design of efficient gene delivery vectors is a challenging task in gene therapy. Recent progress in living/controlled radical polymerizations (LRPs), in particular atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization providing a means for the design and synthesis of new polymeric gene vectors with well-defined compositions, architectures and functionalities is reviewed here. Polymeric gene vectors with different architectures, including homopolymers, block copolymers, graft copolymers, and star-shaped polymers, are conveniently prepared via ATRP and RAFT polymerization. The corresponding synthesis strategies are described in detail. The recent research activities indicate that ATRP and RAFT polymerization have become essential tools for the design and synthesis of advanced, noble and novel gene carriers.     

Modeling and theoretical development in controlled radical polymerization

Controlled radical polymerization (CRP) systems have gained increasing interests for the past two decades. Numerous publications may be found in the literature reporting experimental and modeling work on various CRP processes, including their use in surface modification through grafting. Knowledge of underlying mechanism behind polymerization systems is valuable for product design and process optimization. This information may be obtained through the combination of modeling and experimental studies. In this review, published studies on kinetic and stochastic based modeling for CRP systems are summarized. Their relevance in model discrimination of proposed mechanisms is discussed. This review also includes various parameter estimation studies, that is crucial to obtain accurate simulation predictions. Existing issues on the fundamental mechanism in CRP processes are also addressed.     

端羟基聚丙烯酸异辛酯及聚丙烯酸异辛酯-氨酯的制备及表征

采用原子转移自由基聚合(ATRP)合成了分子量与设计分子量(2000)大小相符的聚丙烯酸异辛酯,再以N-甲基单乙醇胺作为亲核试剂,对活性端基溴进行亲核取代,得到了分子量可控、分子量分布较窄的线型端羟基聚丙烯酸异辛酯。以此为原料与甲苯二异氰酸酯(TDI)反应,制备得到了聚丙烯酸异辛酯-氨酯。利用核磁共振谱(1HNMR)、差示扫描量热仪(DSC)、热重示差扫描量热仪(TGA)对合成的端羟基聚丙烯酸异辛酯及聚丙烯酸酯异辛酯-氨酯的结构、热稳定性等进行了表征。结果表明,利用端羟基聚丙烯酸异辛酯成功地制备了聚丙烯酸异辛酯-氨酯,由凝胶渗透色谱仪(GPC)测得其分子量为10200,玻璃化转变温度为-54℃,是一种新型的丙烯酸酯与聚氨酯的共聚物。     

The potential of Cu(I)Cl/2,2′‐bipyridine catalysis in a triblock copolymer preparation by atom transfer radical polymerization

The ability of atom transfer radical polymerization (ATRP) in the sequential synthesis of triblock copolymers was examined using Cu(I)Cl/2,2′‐bipyridine catalysis at 110°C in toluene, starting from PMMA macroinitiators terminated with the C‐Br group. The PMMAs were prepared by living anionic or group transfer polymerization (GTP), followed by bromination of the respective active site with Br₂ or N‐bromosuccinimide (NBS). The yield of the terminal bromination in the products of both living polymerizations was 60–64% at best, compared with the yield of the bromination of 1‐methoxy‐(1‐trimethylsilyloxy)prop‐1‐ene (a model of the GTP active site) with NBS, as found by ¹H‐NMR. The PMMA macroinitiators prepared were utilized to start the sequential ATRP, finally affording PMMA‐b‐PBuA‐b‐PSt (M_n 69,100), PMMA‐b‐PSt‐b‐PBuA (M_n 21,300) and PMMA‐b‐PSt‐b‐PMMA (M_n 35,200), which have not yet been synthesized by ATRP. After the second block has been formed, the Br‐unterminated part of PMMA macroinitiator was removed by extraction or repeated precipitation. In the third (last) sequence polymerization, induction periods were observed. The first two triblock copolymers were free of precursors and have M_w/M_n values 1.5–1.6 (SEC). In the course of the last step of PMMA‐b‐PSt‐b‐PMMA synthesis, the content of the PMMA‐b‐PSt precursor slowly decreased with increasing MMA conversion. Still, at ≈90% MMA conversion, about 10–15% of the precursor remained in the product. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3514–3522, 2001     

原子转移自由基聚合合成具有pH敏感性壳聚糖材料及其对辅酶A的控制释放

合成了大分子引发剂壳聚糖(CS)接枝α-溴代异丁酰溴(CS-Br),然后利用原子转移自由基聚合(ATRP)合成了一种新型pH敏感性的壳聚糖材料———壳聚糖接枝α-溴代异丁酰溴共聚甲基丙烯酸聚乙二醇酯P(CS-Br-PEGMA),并对其结构进行了表征,研究了其对辅酶A(CoA)的控制释放,结果发现在24℃、P(CS-Br-PEGMA)在不同浓度或pH在3.7~9之间变化时,聚合物都能对辅酶A进行控制释放,同时对其控制释放机理进行初步探讨。     

Synthesis and characterization of poly(vinyl chloride‐co‐vinyl acetate)‐graft‐poly[(meth)acrylates] by atom transfer radical polymerization

The graft polymerization of methyl methacrylate and butyl acrylate onto poly(vinyl chloride‐co‐vinyl acetate) with atom transfer radical polymerization (ATRP) was successfully carried out with copper(I) thiocyanate/N,N,N′,N′,N″‐pentamethyldiethylenetriamine and copper(I) chloride/2,2′‐bipyridine as catalysts in the solvent N,N‐dimethylformamide. For methyl methacrylate, a kinetic plot of ln([M]₀/[M]) (where [M]₀ is the initial monomer concentration and [M] is the monomer concentration) versus time for the graft polymerization was almost linear, and the molecular weight of the graft copolymer increased with increasing conversion, this being typical for ATRP. The formation of the graft polymer was confirmed with gel permeation chromatography, ¹H‐NMR, and Fourier transform infrared spectroscopy. The glass‐transition temperature of the copolymer increased with the concentration of methyl methacrylate. The graft copolymer was hydrolyzed, and its swelling capacity was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 183–189, 2005     

Atom transfer radical polymerization (ATRP): A versatile and forceful tool for functional membranes

The progress in atom transfer radical polymerization (ATRP) provides an effective means for the design and preparation of functional membranes. Polymeric membranes with different macromolecular architectures applied in fuel cells, including block and graft copolymers are conveniently prepared via ATRP. Moreover, ATRP has also been widely used to introduce functionality onto the membrane surface to enhance its use in specific applications, such as antifouling, stimuli-responsive, adsorption function and pervaporation. In this review, the recent design and synthesis of advanced functional membranes via the ATRP technique are discussed in detail and their especial advantages are highlighted by selected examples extract the principles for preparation or modification of membranes using the ATRP methodology.     

Rapid ambient temperature atom transfer radical polymerization of tert‐butyl acrylate

BACKGROUND: Atom transfer radical polymerization (ATRP) is considered to be one of the better and easier synthetic tools for the preparation of polymers with controlled molecular weights and polydispersities. Ambient temperature ATRP of tert‐butyl acrylate (tBA) was studied in a detailed manner with ethyl 2‐bromoisobutyrate (EBrB) and tert‐butyl 2‐bromoisobutyrate (tBuBrB) as the initiators for three different degrees of polymerization. RESULTS: Details pertaining to the kinetics of polymerization using different initiators are reported. It is observed that dimethylsulfoxide accelerates the polymerization at room temperature. The use of Cu(II) as the deactivator produces very narrow dispersity polymers. A diblock copolymer, poly(tert‐butyl acrylate)‐block‐poly(methyl methacrylate), was synthesized from the poly(tBA) macroinitiator demonstrating the controlled living nature of the polymerizations. CONCLUSIONS: The rate of polymerization is more rapid with a secondary initiator (ethyl 2‐bromopropionate) compared to the tertiary initiators EBrB and tBuBrB. From the detailed kinetic results it is observed that tris(2‐dimethylaminoethyl)amine was a better ligand compared to tris(2‐aminoethyl)amine in terms of achieving controlled polymerization. Copyright © 2007 Society of Chemical Industry     

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。     

Atom transfer radical polymerization of styrene and methyl (meth)acrylates initiated with poly(dimethylsiloxane) macroinitiator: Synthesis and characterization of triblock copolymers

Poly(dimethylsiloxane)(PDMS)‐based triblock copolymers were successfully synthesized via atom transfer radical polymerization (ATRP) initiated with bis(bromoalkyl)‐terminated PDMS macroinitiator (Br‐PDMS‐Br). First, Br‐PDMS‐Br was prepared by reaction between the bis(hydroxyalkyl)‐terminated PDMS and 2‐bromo‐2‐methylpropionyl bromide. PSt‐b‐PDMS‐b‐PSt, PMMA‐b‐PDMS‐b‐PMMA and PMA‐b‐PDMS‐b‐PMA triblock copolymers were then synthesized via ATRP of styrene (St), methyl methacrylate (MMA) and methyl acrylate (MA), respectively, in the presence of Br‐PDMS‐Br as a macroinitiator and CuCl/PMDETA as a catalyst system at 80 ^oC. Triblock copolymers were characterized by FTIR, ¹H‐NMR and GPC techniques. GPC results showed linear dependence of the number‐average molecular weight on the conversion as well as the narrow polydispersity indicies (PDI < 1.57) for the synthesized triblock copolymers which was lower than that of Br‐PDMS‐Br macroinitiator (PDI = 1.90), indicating the living/controlled characteristic of the reaction. Also, there was a very good agreement between the number‐average molecular weight calculated from ¹HNMR spectra and that calculated theoretically. Results showed that resulting copolymers have two glass transition temperatures, indicating that triblock copolymers have microphase separated morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Block, blocky gradient and random copolymers of 2-ethylhexyl acrylate and acrylic acid by atom transfer radical polymerization

The controlled synthesis of low-T_g poly(2-ethylhexyl acrylate) (P2EHA) and derived random, block and blocky gradient copolymers via atom transfer radical polymerization (ATRP) is described. After optimizing the reaction conditions for the homopolymerization of 2EHA via ATRP, the synthesis of a variety of copolymers with poly(t-butyl acrylate) (PtBuA) was investigated. First, AB-block copolymers were targeted, starting from P2EHA and PtBuA as macroinitiators. Second, random copolymers of tBuA and 2EHA with different monomer ratios were synthesized. Finally, the synthesis of “blocky” gradient copolymers via a one-pot procedure was investigated, starting with the homopolymerization of tBuA, followed by the addition of 2EHA. The hydrolysis of the PtBuA-segments to poly(acrylic acid) (PAA), which was carried out with methanesulfonic acid, resulted in block, blocky gradient and random copolymers consisting of PAA and P2EHA. Solubility testing of the copolymers in slightly basic water (pH ∼ 9) demonstrated that the gradient structure significantly enhances solubility compared to the block copolymer structures with equal composition. The polymers have been characterized by MALDI-TOF MS, GPC and ¹H NMR.     

Preparation of hydrogel nanoparticles by atom transfer radical polymerization of N-isopropylacrylamide in aqueous media using PEG macro-initiator

PEG-b-PNIPAM block copolymers are synthesized by the atom transfer radical polymerization of NIPAM using PEG macro-initiator. When the polymerization temperature is 25 °C, the block copolymer is soluble in water, whereas the block copolymer is phase-separated to form micelles during polymerization as the polymerization temperature is raised to 50 °C, the temperature above the LCST of PEG-b-PNIPAM. To prepare stable hydrogel nanoparticles in water at room temperature, a small amount of N,N′-ethylenebisacrylamide is added as a cross-linker to the reaction system, where the size of nanoparticles is controlled by the composition of mixed solvent.     

Surface‐initiated atom transfer radical polymerization of regenerated cellulose membranes with thermo‐responsive properties

Using atom transfer radical polymerization (ATRP), thermo‐responsive regenerated cellulose membranes were synthesized. Regenerated cellulose membranes were firstly modified by reacting the hydroxyl groups on the surface with 2‐bromoisobutyryl bromide, followed by grafting with poly(N‐isopropylacrylamide). The membranes had obvious thermally modulated permeability properties. Analysis was carried out by means of X‐ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results showed that N‐isopropylacrylamide had been grafted successfully on the surface of the regenerated cellulose membranes. The thermally modulated permeability properties of the grafted membranes were studied using water flux measurements. It was found that the thermally modulated permeability properties of a cellulose surface can be tailored by the use of the ATRP method. Copyright © 2010 Society of Chemical Industry     

Synthesis of poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate) triblock copolymer by atom transfer radical polymerization

The synthesis of triblock copolymer poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate), using atom transfer radical polymerization (ATRP), is reported. The copolymers were prepared in two steps. First, polystyrene was synthesized by ATRP using α,α′‐dichloro‐p‐xylene/CuBr/bpy as the initiating system; Second, polystyrene was further used as macroinitiator for the ATRP of octadecyl acrylate to prepare ABA triblock copolymers in the presence of FeCl₂·4H₂O/PPh₃ in toluene. Polymers with controlled molecular weight (M_n = 17,000–23,400) and low polydispersity index value (1.33–1.44) were obtained. The relationship between molecular weight versus conversion showed a straight line. The effect of reaction temperature on polymerization was also investigated, showing a faster polymerization rate under higher temperature. The copolymers were characterized by FTIR, ¹H‐NMR, DSC, and GPC and the crystallization behavior of the copolymers was also studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1539–1545, 2004     

New fluorous bipyridine ligands for copper‐catalyzed atom transfer radical polymerization of methyl methacrylate in the thermomorphic mode

The atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) is often carried out under homogeneous conditions, so the residual metal catalyst in the polymer often influences the quality of the polymer and causes environmental pollution in the long run. Novel CuBr/4,4′‐bis(R_fCH₂OCH₂)‐2,2′‐bpy complexes (R_f = n‐C₉F₁₉, n‐C₁₀F₂₁, or n‐C₁₁F₂₃; 2,2′‐bpy = 2,2′‐bipyridine) are insoluble in toluene at room temperature yet readily dissolve in toluene at elevated temperatures to form homogeneous phases for use as catalysts in the ATRP reaction, and the Cu complexes precipitate again upon cooling. The CuBr/4,4′‐bis(n‐C₉F₁₉CH₂OCH₂)‐2,2′‐bpy system produced the best results (e.g., polydispersity index by gel permeation chromatography = 1.26–1.41), in that the residual Cu content in the polymer was as low as 19.3 ppm when the ATRP of MMA was carried out in the thermomorphic mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Atom transfer radical polymerization grafting of highly functionalized polystyrene and poly(4‐methylstyrene) macroinitiators with tert‐butyl acrylate

Two monodisperse graft copolymers, poly(4‐methylstyrene)‐graft‐poly(tert‐butyl acrylate) [number‐average molecular weight (M_n) = 37,500, weight‐average molecular weight/number‐average molecular weight (M_w/M_n) = 1.12] and polystyrene‐graft‐poly(tert‐butyl acrylate) (M_n = 72,800, M_w/M_n = 1.12), were prepared by the atom transfer radical polymerization of tert‐butyl acrylate catalyzed with Cu(I) halides. As macroinitiators, poly{(4‐methylstyrene)‐co‐[(4‐bromomethyl)styrene]} and poly{styrene‐co‐[4‐(1‐(2‐bromopropionyloxy)ethyl)styrene]}, carrying 40% of the bromoalkyl functionalities along the chain, were used. The dependencies of molecular parameters on monomer conversion fulfilled the criteria for controlled polymerizations. In contrast, the dependencies of monomer conversion versus time were nonideal; possible causes were examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2930–2936, 2002     

Complex polymer architectures via RAFT polymerization: From fundamental process to extending the scope using click chemistry and nature's building blocks

Reversible addition fragmentation chain transfer (RAFT) polymerization has made a huge impact in macromolecular design. The first block copolymers were described early on, followed by star polymers and then graft polymers. In the last five years, the types of architectures available have become more and more complex. Star and graft polymers now have block structures within their branches, or a range of different branches can be found growing from one core or backbone. Even the synthesis of hyperbranched polymers can be positively influenced by RAFT polymerization, allowing end group control or control over the branching density. The creative combination of RAFT polymerization with other polymerization techniques, such as ATRP or ring-opening polymerization, has extended the array of available architectures. In addition, dendrimers were incorporated either as star core or endfunctionalities. A range of synthetic chemistry pathways have been utilized and combined with polymer chemistry, pathways such as ‘click chemistry’. These combinations have allowed the creation of novel structures. RAFT processes have been combined with natural polymers and other naturally occurring building blocks, including carbohydrates, polysaccharides, cyclodextrins, proteins and peptides. The result from the intertwining of natural and synthetic materials has resulted in the formation of hybrid biopolymers. Following these developments over the last few years, it is remarkable to see that RAFT polymerization has grown from a lab curiosity to a polymerization tool that is now been used with confidence in material design. Most of the described synthetic procedures in the literature in recent years, which incorporate RAFT polymerization, have been undertaken in order to design advanced materials.