Synthesis and coordination of oxyquinolyl end‐functionalized polystyrene by atom transfer radical polymerization

The end‐functionalized polystyrene is synthesized by a new initiator, 5‐chloromethyl‐8‐hydroxyquinoline (5‐ClCH₂Q), via atom transfer radical polymerization. The existence of the oxyquinoline group on the chain end was confirmed by ¹H‐NMR. The polymers can be easily changed into films with good fluorescence property and nonlinear third‐order optical property. Coordinating the oxyquinoline group with Eu³⁺ and La³⁺, the fluorescent intensity and third‐order nonlinear optical coefficient will be enhanced much more. The proportion of the oxyquinoline group coordinating and rare‐earth metal is 3:2 determined by titrimetric analysis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2067–2071, 2005     

Synthesis of poly(cyclohexene oxide)‐block‐polystyrene by combination of radical‐promoted cationic polymerization,atom transfer radical polymerization and click chemistry

The combination of radical‐promoted cationic polymerization, atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of poly(cyclohexene oxide)‐block‐polystyrene (PCHO‐b‐PSt). Alkyne end‐functionalized poly(cyclohexene oxide) (PCHO‐alkyne) was prepared by radical‐promoted cationic polymerization of cyclohexene oxide monomer in the presence of 1,2‐diphenyl‐2‐(2‐propynyloxy)‐1‐ethanone (B‐alkyne) and an onium salt, namely 1‐ethoxy‐2‐methylpyridinium hexafluorophosphate, as the initiating system. The B‐alkyne compound was synthesized using benzoin photoinitiator and propargyl bromide. Well‐defined bromine‐terminated polystyrene (PSt‐Br) was prepared by ATRP using 2‐oxo‐1,2‐diphenylethyl‐2‐bromopropanoate as initiator. Subsequently, the bromine chain end of PSt‐Br was converted to an azide group to obtain PSt‐N₃ by a simple nucleophilic substitution reaction. Then the coupling reaction between the azide end group in PSt‐N₃ and PCHO‐alkyne was performed with Cu(I) catalysis in order to obtain the PCHO‐b‐PSt block copolymer. The structures of all polymers were determined. Copyright © 2010 Society of Chemical Industry     

Synthesis of multi‐arm star polystyrene with hyperbranched polyester initiators by atom transfer radical polymerization

Multi‐arm star polystyrenes with hyperbranched polyester (HP3) core were prepared by atom transfer radical polymerization (ATRP). The structures of the polymers were investigated with FTIR and ¹H NMR. GPC results showed that the resultant polymers had relatively broad polydispersity indices that arouse from the macromolecular initiator (HP3‐Br). The thermal properties were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC analysis indicated that polystyrene star polymers had only the glass transition temperatures (T_g), which changes with the weight ratio of multi‐functional macroinitiator‐to‐monomer. In addition, these star polymers could form the spherical micelles in the selected solvent (THF/n‐hexane). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 728–733, 2006     

Synthesis and fluorescence properties of star‐shaped polymers carrying two fluorescent moieties

A well‐defined fluorescent star‐shaped polymer containing two different fluorescent functionalities one in the main chain and another in the end group was designed and synthesized by combining atom transfer radical polymerization (ATRP) and azide‐alkyne click reaction. The star polymer with four arms was prepared from copolymerization of methyl methacrylate and 4‐(2‐(9‐anthryl))‐vinyl‐styrene using ATRP. Subsequently the end group was modified with another fluorescent moiety by click coupling. The structure of all the intermediate and final products was established through NMR spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, UV?visible spectroscopy and fluorescence spectroscopy. The novel hybrid polymer exhibits an attractive high fluorescence at 494 nm and over a broad range which was a combination of both the fluorescence moieties. © 2013 Society of Chemical Industry     

High‐molecular‐weight polyacrylonitrile by atom transfer radical polymerization

A single‐pot atom transfer radical polymerization was used for the first time to successfully synthesize polyacrylonitrile with a molecular weight higher than 80,000 and a narrow polydispersity as low as 1.18. This was achieved with CuBr/isophthalic acid as the catalyst, 2‐bromopropionitrile as the initiator, and N,N‐dimethylformamide as the solvent. The effects of the solvent on the polymerization of acrylonitrile were also investigated. The induction period was shorter in N,N‐dimethylformamide than in propylene carbonate and toluene, and the rate of the polymerization in N,N‐dimethylformamide was fastest. The molecular weight of polyacrylonitrile agreed reasonably well with the theoretical molecular weight in N,N‐dimethylformamide. When chlorine was used in either the initiator or the catalyst, the rate of polymerization showed a trend of decreasing, and the molecular weight deviated from the theoretical predication significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3372–3376, 2006     

Synthesis and characterization of Pst‐b‐PDMS‐b‐PSt copolymers by atom transfer radical polymerization

Polystyrene‐b‐poly(dimethylsiloxane)‐b‐polystyrene (Pst‐b‐PDMS‐b‐PSt) triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). Commercially available difunctional PDMS containing vinylsilyl terminal species was reacted with hydrogen bromide, resulting in the PDMS macroinitiators for the ATRP of styrene (St). The latter procedure was carried out at 130°C in a phenyl ether solution with CuCl and 4, 4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) as the catalyzing system. By using this technique, triblock copolymers consisting of a PDMS center block and polystyrene terminal blocks were synthesized. The polymerization was controllable; ATRP of St from those macroinitiators showed linear increases in M_n with conversion. The block copolymers were characterized with IR and ¹H‐NMR. The effects of molecular weight of macroinitiators, macroinitiator concentration, catalyst concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3764–3770, 2004     

Synthesis of well-defined star polymers and star block copolymers from dendrimer initiators by atom transfer radical polymerization

Novel polyarylether dendrimers with 1,3,5-tri(4-hydroxyphenoxy)benzene core, polybenzylether interior, and benzyl 2-bromoisobutyrate surface group (CMGn-Br, n=1-3, with functionality of 6, 12, and 24, respectively) were prepared by convergent procedure. ATRP of tert-butyl acrylate (tBA) and styrene (St) with CMGn-Br dendrimer initiators in the presence of CuBr/pentamethyldiethylenetriamine catalytic system was investigated in detail, and a series of well-defined dendrimer-like star PtBA and PSt with precise arm numbers were synthesized under suitable conditions. The quantitative initiation of the dendrimer initiators was demonstrated by high initiation efficiency, ¹H NMR spectra, hydrolysis, and MALLS/SEC approach. Star block copolymers comprising PSt and PtBA segments with low polydispersity (1.08<M_w/M_n<1.18) were also successfully synthesized using functional macroinitiators by block copolymerization. In addition, the thermal properties of the resultant polymers were characterized by DSC and TGA.     

Synthesis and characterization of PBMA‐b‐PDMS‐b‐PBMA copolymers by atom transfer radical polymerization

Poly(butyl methylacrylate)–b–poly(dimethylsiloxane)–b–poly(butyl methylacrylate) (PBMA–b–PDMS–b–PBMA) triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). The reaction of α,ω‐dichloride PDMS with 2′‐hydroxyethyl‐2‐bromo‐2‐methylpropanoate gave suitable macroinitiators for the ATRP of BMA. The latter procedure was carried out at 110°C in a phenyl ether solution with CuCl and 4,4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) as the catalyzing system. The polymerization was controllable, with the increase of the monomer conversion, there was a nearly linear increase of molecular weight and a decrease of polydispersity in the process of the polymerization, and the rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with IR and ¹H‐NMR and differential scanning calorimetry. The effects of macroinitiator concentration, catalyst concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP were reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 532–538, 2004     

Controlled grafting of polymer brushes on poly(vinylidene fluoride) films by surface‐initiated atom transfer radical polymerization

Controlled grafting of well‐defined polymer brushes on the poly(vinylidene fluoride) (PVDF) films was carried out by the surface‐initiated atom transfer radical polymerization (ATRP). Surface‐initiators were immobilized on the PVDF films by surface hydroxylation and esterification of the hydroxyl groups covalently linked to the surface with 2‐bromoisobutyrate bromide. Homopolymer brushes of methyl methacrylate (MMA) and poly(ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the α‐bromoester‐functionalized PVDF surface. The chemical composition of the graft‐functionalized PVDF surfaces was characterized by X‐ray photoelectron spectroscopy (XPS) and attenuated total reflectance (ATR)–FTIR spectroscopy. Kinetics study revealed a linear increase in the graft concentration of PMMA and PEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a “controlled” or “living” process. The “living” chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3704–3712, 2006     

Synthesis and characterization of PMMA‐b‐PBMA block copolymers by atom transfer radical polymerization

The synthesis of diblock copolymers using atom transfer radical polymerization, ATRP, of n‐butyl methacrylate, BMA, and methyl methacrylate, MMA, is reported. These copolymers were prepared from 2‐bromoisobutyryl‐terminated macroinitiators of poly(MMA) and poly(BMA), using copper chloride, CuCl,/N,N,N′,N″,N″‐pentamethyldiethylenetretramine, PMDETA, as the catalyst system, at 100°C in bulk and in benzonitrile solution. The block copolymers were characterized by means of size‐exclusion chromatography, SEC, and ¹H‐NMR spectroscopy. The SEC analysis of the synthesized diblock copolymers confirmed important differences in the molecular weight control depending on the reaction medium (solvent effect) and the chemical structure of the macroinitiator used. In addition, differential scanning calorimetry, (DSC) measurements were performed, showing for all the copolymers a phase separation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2683–2691, 2002     

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     

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.     

Graft copolymers and high‐molecular‐weight star‐like polymers by atom transfer radical polymerization

Grafting of tert‐butyl acrylate (tBuA), methyl methacrylate (MMA), and styrene (St) monomers (M) by Cu(I)‐mediated ATRP from polystyrene (PSt) macroinitiator (M_n = 5620, polydispersity index, PDI = 1.12), containing initiating 2‐bromopropionyloxy groups (I) (bound to 34% of aromatic cores; 11 groups per backbone), was performed using conditions suitable for the respective homopolymerizations. The preparation of PSt‐g‐PtBuA in bulk using an initial molar ratio [M]₀/[I]₀ = 140 had a controlled character up to M_n = (132–148) × 10³ (PDI = 1.08–1.16). With MMA and St and using the same [M]₀/[I]₀, preliminary experiments were made; the higher the monomer conversion, the broader was the distribution of molecular weight of the products. Graft copolymerizations of all these monomers at [M]₀/[I]₀ = 840 or 1680 were successfully conducted up to high conversions. Low‐polydispersity copolymers, with very long side chains, in fact star‐like copolymers, were obtained mainly by tuning the deactivator amount in the reaction mixture. (PSt‐g‐PtBuA, DP_n,sc (DP of side chain) = 665, PDI = 1.24; PSt‐g‐PMMA, DP_n,sc = 670, PDI = 1.43; PSt‐g‐PSt, DP_n,sc = 324, PDI = 1.11). Total suppression of intermolecular coupling was achieved here. However, the low concentrations of initiator required long reaction times, leading sometimes to formation of a small amount (～5%) of low‐molecular‐weight polymer fraction. This concomitant process is discussed, and some measures for its prevention are proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3662–3672, 2006     

Synthesis of fluorinated polymer electrolyte membranes by radiation grafting and atom transfer radical polymerization techniques

A novel polymer electrolyte membrane was synthesized by radiation-induced grafting and consequent atom transfer radical polymerization (ATRP). First, bromine-containing perfluorinated grafts were prepared by radiation grafting of 2-bromotetrafluoroethyl trifluorovinyl ether (BrTFF) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film. Then, the bromine atoms in the ETFE-g-PBrTFF grafted films were acted as initiators, and the films were treated with Cu(I)-based catalytic system of a CuBr and 2,2′-bipyridyl (bpy) for the ATRP. By adjusting the molar ratio of initiator/CuBr/bpy and the reaction temperature, branched poly(styrene) with a grafting yield of above 100% on the poly(BrTFF) main chains was constructed in ETFE-g-PBrTFF films. Thermal analysis revealed that the perfluorinated poly(BrTFF) main chains were miscible to ETFE, whereas the hydrocarbon poly(styrene) branches were phase-separated from the ETFE-g-PBrTFF film. Sulfonic groups could be further introduced into the poly(styrene) grafts of ETFE-g-PBrTFF-g-PS films with homogeneous distribution in a perpendicular direction to the membrane surface. The resulting membrane with a styrene grafting yield of 15% exhibited higher proton conductivity than commercial Nafion 117 membrane. Likewise, it had better chemical stability than ETFE-g-PSSA membrane prepared by conventional radiation-induced grafting.     

Well-defined dibenzocyclooctyne end functionalized polymers from atom transfer radical polymerization

The dibenzocyclooctyne end functionalized agent 1 was designed as atom transfer radical polymerization (ATRP) initiator. The ATRP was then explored on three types of monomers widely used in free radical polymerization: methyl methacrylate, styrene, and acrylates (n-butyl acrylate and tert-butyl acrylate). The living polymerization behaviors were obtained for the methyl methacrylate and styrene monomers. The SPAAC click reactivity of dibenzocyclooctyne end group were demonstrated by successfully reacting with azide functionalized small chemical agents and polymers. Various topological polymers such as block and brush polymers were produced from strain-promoted azide-alkyne cycloaddition reaction (SPAAC) using the resultant dibenzocyclooctyne end functionalized poly(methyl methacrylate)/polystyrene as building blocks. For the acrylates, however, the polymerization did not hold the living characteristics with the dibenzocyclooctyne end functionalized ATRP initiator 1.     

Modification of ramie fiber with an amine‐containing polymer via atom transfer radical polymerization

The covalent bonding of tertiary amine 2‐(dimethylamino)ethyl methacrylate to ramie fiber via atom transfer radical polymerization was obtained with a brominated initiator and the catalyst CuCl/1,10‐phenanthroline. The results reveal that poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) was successfully immobilized on the surface of the ramie fiber in a controlled polymerization. After the grafting with PDMAEMA, the crystal structure of cellulose I in the ramie fiber was still preserved, and the lateral size of the microfibrils, calculated on the basis of plane 002, was slightly increased. As a demonstration of possible applications, the modified fiber was dyed with CI Reactive Red 2. The dye uptake, which almost linearly increased with increasing molecular weight of PDMAEMA attached on the ramie fiber, was raised to be over 15 times that of the raw fiber. The reason was that the reactivity between the tertiary amines in PDMAEMA and the dichlorotriazinyl group in the dye molecules was much higher than that between the hydroxyl groups in the ramie fiber and the reactive groups in the dye molecules. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polymerization of sodium 4-styrenesulfonate via atom transfer radical polymerization in protic media

The homopolymerization of sodium 4-styrenesulfonate (NaStS) in both aqueous and water/methanol solutions at 20 °C using atom transfer radical polymerization (ATRP) is described. Syntheses conducted using a sodium 4-bromomethylbenzoate initiator were poorly controlled in water but reasonably well-controlled in 1:1 water/methanol mixtures, with 3:1 water/methanol mixtures exhibiting intermediate behavior. In 1:1 water/methanol mixtures aqueous GPC analyses indicated polydispersities as low as 1.26 and conversions reached 80-90% within 18-20 h at 20 °C. Self-blocking experiments were conducted in 1:1 water/methanol mixtures, with the chain-extended NaStS polymers exhibiting unimodal GPC traces but relatively high polydispersities (M_w/M_n=1.61). The use of poly(ethylene oxide)-based (PEO) macro-initiators yielded novel PEO-NaStS diblock copolymers of low polydispersity. Diblock copolymer syntheses via sequential monomer addition were less satisfactory, although one example of a polydisperse pH-responsive diblock copolymer was obtained.     

Synthesis of water‐soluble and conducting polyaniline by growing of poly (N‐isopropylacrylamide) brushes via atom transfer radical polymerization method

Polyaniline‐graft‐Poly(N‐isopropylacrylamide) copolymers were synthesized by atom‐transfer radical polymerization (ATRP) of N‐isopropylacrylamide using polyaniline macro‐initiators. Polyaniline‐chloroacetylchloride and polyaniline‐chloropropionylchloride macroinitiators were obtained by the reaction of amine nitrogens of polyaniline with chloroacetyl chloride and 2‐choloropropionyl choloride, respectively. Both macroinitiators and graft copolymers were characterized by FT‐IR and ¹H‐NMR spectroscopy. The cyclic voltammetry (CV) and UV‐Vis spectroscopy studies showed that these copolymers are electroactive. The solubility test revealed that the polyaniline‐graft‐poly (N‐isopropylacrylamide) copolymers are water soluble or water/methanol soluble. The Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) images showed the growing of poly (N‐isopropylacrylamide) chains on polyaniline backbone. Investigation of thermal behavior of graft copolymers by thermal gravimetry analysis (TGA) confirmed the results obtained from AFM and SEM images. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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。