ATRP法合成两亲性嵌段共聚物PSt-b-PAA及其在离子液体[BMIM][PF6]中的自组装行为研究

利用原子转移自由基聚合法(ATRP)合成了分子量可控、分子量分布窄的嵌段共聚物聚苯乙烯-b-聚丙烯酸叔丁酯(PSt-b-PtBA), 进而在酸性条件下由水解反应得到了两亲性嵌段共聚物聚苯乙烯-b-聚丙烯酸(PSt-b-PAA), 并通过凝胶渗透色谱(GPC)、傅立叶变换红外光谱(FTIR)、核磁共振(1H NMR)等测试手段对产物进行了表征. 使三种分子量不同的两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM][PF6])中进行自组装, 通过激光粒度分析仪(DLS)和透射电子显微镜(TEM)研究了聚合物在离子液体中自组装的胶束尺寸和结构形态. 当PSt的链段长度一定时, 胶束的形状主要依赖于PAA链的长度. 当PAA链段较长时, 胶束呈球形; 当PAA链段较短时, 则变成不规则的花生状胶束.     

两亲性嵌段共聚物PAA-b-PS的合成及胶束形态

通过丙烯酸叔丁酯的自由基调聚和苯乙烯的原子转移自由基聚合（ATRP）法合成了聚丙烯酸叔丁酯-聚苯乙烯（PtBA-b-PS）嵌段共聚物,然后在三氟乙酸作用下进行选择性水解得到了两亲性聚丙烯酸-聚苯乙烯（PAA-b-PS）嵌段共聚物。利用1H-NMR、FT-IR和GPC对产物的结构进行了表征。采用透析法制备了PAA-b-P...     

Low molar mass poly(styrene-co-acrylic acid) amphiphilic block copolymers: synthesis and characterization

Low molar mass (∼ 4000) di- and triblock copolymers of styrene and tert-butyl acrylate were synthesized by atom transfer radical polymerization (ATRP) in bulk and solution conditions. A CuBr/N, N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) catalyst system in conjunction with an alkyl-halide initiator were used to control the synthesis of the polystyrene macroinitiator and the subsequent copolymerization with tert-butyl acrylate. Hydrolysis of the tert-butyl acrylate blocks to acrylic acid blocks in the presence of trifluoroacetic acid resulted in the formation of an amphiphilic block copolymer. Size exclusion chromatography (SEC) and matrix assisted laser desorption ionization - time of flight - mass spectrometry (MALDI-TOF-MS) were used to determine the molar mass and molar mass distribution of the polystyrene macroinitiators and the block copolymers. ¹H NMR was used to characterize the polystyrene macroinitiators and the block copolymers, and to confirm hydrolysis of the poly(tert-butyl acrylate) blocks to poly(acrylic acid).     

Novel amphiphilic graft copolymers bearing hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains

A novel amphiphilic graft copolymer consisting of hydrophilic poly(acrylic acid) backbones and hydrophobic poly(butyl methacrylate) side chains was synthesized by successive atom transfer radical polymerization followed by hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distributions (polydispersity index < 1.40). Hydrophobic side chains were connected to the backbone through stable C? C bonds instead of ester connections. Poly(methoxymethyl acrylate) backbone was easily hydrolyzed to poly(acrylic acid) backbone with HCl without affecting the hydrophobic side chains. The amphiphilic graft copolymer could form stable micelles in water. The critical micelle concentration in water was determined by a fluorescence probe technique. The morphology of the micelles was preliminarily explored with transmission electron microscopy and was found to be spheres. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6857–6868, 2006     

A starlike amphiphilic graft copolymer with hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains

A well‐defined starlike amphiphilic graft copolymer bearing hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains was synthesized by successive atom transfer radical polymerization followed by the hydrolysis of poly‐(methoxymethyl acrylate) backbone. A grafting‐from strategy was employed for the synthesis of a graft copolymer with narrow molecular weight distribution. Hydrophobic polystyrene side chains were connected to the backbones through stable C? C bonds. The poly(methoxymethyl acrylate) backbones can be easily hydrolyzed with HCl without affecting the hydrophobic polystyrene side chains. This kind of amphiphilic graft copolymer can form stable sphere micelles in water. The sizes of the micelles were dependent on the ionic strength and pH value. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3687–3697, 2007     

Synthesis of AB2 miktoarm star-shaped copolymers by combining stable free radical polymerization and atom transfer radical polymerization

A stable nitroxyl radical functionalized with two initiating groups for atom transfer radical polymerization (ATRP), 4-(2,2-bis-(methyl 2-bromo isobutyrate)-propionyloxy)-2,2,6,6-tetramethyl-1-piperidinyloxy (Br₂-TEMPO), was synthesized by reacting 4-hydroxyl-2,2,6,6-tetramethyl-1-piperidinyloxy with 2,2-bis-(methyl 2-bromo isobutyrate) propanoic acid. Stable free radical polymerization of styrene was then carried out using a conventional thermal initiator, dibenzoyl peroxide, along with Br₂-TEMPO. The obtained polystyrene had two active bromine atoms for ATRP at the ω-end of the chain and was further used as the macroinitiator for ATRP of methyl acrylate and ethyl acrylate to prepare AB₂-type miktoarm star-shaped copolymers. The molecular weights of the resulting miktoarm star-shaped copolymers at different monomer conversions shifted to higher molecular weights without any trace of the macroinitiator, and increased with monomer conversion.     

Preparation of polyethylene block copolymers by a combination of postmetallocene catalysis of ethylene polymerization and atom transfer radical polymerization

The synthesis of block copolymers consisting of a polyethylene segment and either a poly(meth)acrylate or polystyrene segment was accomplished through the combination of postmetallocene-mediated ethylene polymerization and subsequent atom transfer radical polymerization. A vinyl-terminated polyethylene (number-average molecular weight = 1800, weight-average molecular weight/number-average molecular weight =1.70) was synthesized by the polymerization of ethylene with a phenoxyimine zirconium complex as a catalyst activated with methylalumoxane (MAO). This polyethylene was efficiently converted into an atom transfer radical polymerization macroinitiator by the addition of α-bromoisobutyric acid to the vinyl chain end, and the polyethylene macroinitiator was used for the atom transfer radical polymerization of n-butyl acrylate, methyl methacrylate, or styrene; this resulted in defined polyethylene-b-poly(n-butyl acrylate), polyethylene-b-poly(methyl methacrylate), and polyethylene-b-polystyrene block copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 496–504, 2004     

Amphiphilic polymer conetworks prepared by controlled radical polymerization using a nitroxide cross‐linker

Tandem atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMRP) were used to synthesize a polystyrene‐co‐poly(acrylic acid) (poly(St‐co‐AA)) network, in which the two components were interconnected by covalent bond. First, a specific cross‐linker, 1,4‐bis(1′‐(4″‐acryloyloxy‐2″,2″,6″,6″‐tetramethylpiperidinyloxy)ethyl)benzene (di‐AET), a bifunctional alkoxyamine possessing two acrylate groups, was copolymerized with tert‐butyl acrylate through ATRP to prepare a precursor gel. The gel was then used to initiate the NMRP of styrene to prepare poly(St‐co‐(t‐BA)) conetwork, in which the cross‐linkages are composed of polystyrene segments. Finally, the poly(St‐co‐(t‐BA)) conetwork was hydrolyzed to produce amphiphilic poly(St‐co‐AA) conetwork. The resulting gels show swelling ability in both organic solvent and water, which is characteristic of amphiphilic conetworks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4141–4149, 2010     

The effects of polyelectrolytes on the inhibition and aggregation of calcium oxalate crystallization

The influence of polyelectrolytes with different architecture on spontaneous batch crystallization of calcium oxalate was investigated. A series of acidic acrylate block copolymers were been made, by radical polymerization, with defined molecular weight and structure. Radical polymerization of acrylic acid (AA) was carried out in the presence of α‐thiopolyethylene glycol monomethylether as a chain transfer agent to produce poly(ethylene glycolblockacrylic acid) copolymers. Poly(ethylene glycol) (PEG) block length in the copolymers was controlled by using three different molecular weight chain transfer agents (M_n = 350, 750 and 2000 g/mol). The presence of copolymers inhibited the crystal growth of calcium oxalate possibly through adsorption onto the active growth sites for crystal growth due to the charge and hydrophilic effects. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis of densely grafted comblike copolymers

Densely grafted copolymers were synthesized using the “grafting from” approach via the combination of reversible addition‐fragment chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP). First, a novel functional monomer, 2,3‐di(2‐bromoisobutyryloxy)ethyl acrylate (DBPPA), with two initiating groups for ATRP was synthesized. It was then polymerized via RAFT polymerization to give macroinitiators for ATRP with controlled molecular weights and narrow molecular weight distributions. Last, ATRP of styrene was carried out using poly(DBPPA)s as macroinitiators to prepare comblike poly(DBPPA)‐graft‐polystyrenes carrying double branches in each repeating unit of backbone via “grafting from” approach. Furthermore, poly(DBPPA)‐graft‐[polystyrene‐block‐poly(t‐BA)]s and their hydrolyzed products poly(DBPPA)‐graft‐[polystyrene‐block‐poly(acrylic acid)]s were also successfully prepared. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 362–372, 2008     

Synthesis of coil‐comb block copolymers containing polystyrene coil and poly(methyl methacrylate) side chains via atom transfer radical polymerization

A series of polystyrene‐b‐(poly(2‐(2‐bromopropionyloxy) styrene)‐g‐poly(methyl methacrylate)) (PS‐b‐(PBPS‐g‐PMMA)) and polystyrene‐b‐(poly(2‐(2‐bromopropionyloxy)ethyl acrylate)‐g‐poly(methyl methacrylate)) (PS‐b‐(PBPEA‐g‐PMMA)) as new coil‐comb block copolymers (CCBCPs) were synthesized by atom transfer radical polymerization (ATRP). The linear diblock copolymer polystyrene‐b‐poly(4‐acetoxystyrene) and polystyrene‐b‐poly(2‐(trimethylsilyloxy)ethyl acrylate) PS‐b‐P(HEA‐TMS) were obtained by combining ATRP and activators regenerated by electron transfer (ARGET) ATRP. Secondary bromide‐initiating sites for ATRP were introduced by liberation of hydroxyl groups via deprotection and subsequent esterification reaction with 2‐bromopropionyl bromide. Grafting of PMMA onto either the PBPS block or the PBPEA block via ATRP yielded the desired PS‐b‐(PBPS‐g‐PMMA) or PS‐b‐(PBPEA‐g‐PMMA). ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography data indicated the target CCBCPs were successfully synthesized. Preliminary investigation on selected CCBCPs suggests that they can form ordered nanostructures via microphase separation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2971–2983     

Synthesis of diblock copolymers by combining stable free radical polymerization and atom transfer radical polymerization

A stable nitroxyl radical functionalized with an initiating group for atom transfer radical polymerization (ATRP), 4‐(2‐bromo‐2‐methylpropionyloxy)‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (Br‐TEMPO), was synthesized by the reaction of 4‐hydroxyl‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy with 2‐bromo‐2‐methylpropionyl bromide. Stable free radical polymerization of styrene was then carried out using a conventional thermal initiator, dibenzoyl peroxide, along with Br‐TEMPO. The obtained polystyrene had an active bromine atom for ATRP at the ω‐end of the chain and was used as the macroinitiator for ATRP of methyl acrylate and ethyl acrylate to prepare block copolymers. The molecular weights of the resulting block copolymers at different monomer conversions shifted to higher molecular weights and increased with monomer conversion. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2468–2475, 2006     

Synthesis of double hydrophilic graft copolymer containing poly(ethylene glycol) and poly(methacrylic acid) side chains via successive ATRP

A well‐defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting‐through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2‐bromopropionyl chloride. Afterwards, grafting‐from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methacrylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli‐responsive to pH and ionic strength. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4056–4069, 2008     

Preparation of platinum nanoparticles using star-block copolymer with a carboxylic core

Well-defined star polymers containing a functionalized core supply a molecular nanocavity and may be used to control formation of inorganic nanoparticles. Herein, platinum (Pt) nanoparticles of 2-4 nm were prepared by using (poly(acrylic acid)-b-polystyrene)6 (PAA-b-PS)6 amphiphilic star block copolymer as a novel single molecular stabilizer. This PAA core functionalized star polymer was obtained by hydrolysis of (poly(tert-butyl acrylate)-b-polystyrene)6 (PtBA-b-PS)6, which was synthesized by sequential atom transfer radical polymerization (ATRP) of tert-butyl acrylate and styrene with an initiator bearing six 2-bromoisobutyloxyl groups. Pt(IV) ions were loaded by ion exchange to the core of the star polymer and Pt nanoparticle stabilized by single star polymer was produced by a reduction with NaBH4.     

Triblock copolymer synthesis via controlled radical polymerization in solution using S‐tert‐alkyl‐N,N‐alkoxycarbonylalkyldithiocarbamate RAFT agents

This paper presents the solution homopolymerization, random and block copolymerization of acrylic monomers, mediated using an S‐(1,4‐phenylenebis(propane‐2,2‐diyl)) bis(N,N‐butoxycarbonylmethyldithiocarbamate) RAFT agent. Fair to good control was obtained over the solution homopolymerization of various acrylic monomers. Although inhibition periods were observed, nearly no retardation was found to occur. Satisfactory control was also obtained over the solution copolymerization of n‐butyl acrylate with methacrylic acid, mediated using this RAFT agent. Finally, triblock copolymer synthesis, starting from the macromolecular intermediates produced in the homo‐ and copolymerization experiments, was studied, and was shown to be successful. The observed relatively broad molar mass distributions could be explained by a partial decomposition of the dithiocarbamate‐based RAFT agent during synthesis and/or polymerization, for which strong indications were obtained by performing a careful MALDI‐ToF MS analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6419–6434, 2006     

PS-b-PNIPAM/Ag复合微粒的制备与表征

采用原子转移自由基聚合(ATRP)法合成了聚苯乙烯-b-聚(N-异丙基丙烯酰胺)(PS-b-PNIPAM)两亲性嵌段共聚物, 并以其为模板, 聚乙烯亚胺(PEI)作为银离子和嵌段共聚物PS-b-PNIPAM的交联剂以及还原剂, 制备了PS-b-PNIPAM/Ag复合纳米微粒. 利用透射电子显微镜(TEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱对复合纳米微粒的形貌及其成分进行了表征. X射线衍射和电子衍射证明银纳米微粒具有良好的面心立方体单晶结构. 研究结果表明, 不同浓度的两亲性嵌段共聚物PS-b-PNIPAM在丙酮中形成的胶束模板对银纳米粒子的尺寸及其分布有重要的影响.     

Synthesis of polar block grafted syndiotactic polystyrenes via a combination of iridium‐catalyzed activation of aromatic C?H bonds and atom transfer radical polymerization

A combination of iridium‐catalyzed C H activation/borylation and atom transfer radical polymerization (ATRP) was used to generate polar graft copolymers of syndiotactic polystyrene (sPS). The borylation at aromatic C H bonds of sPS and subsequent oxidation of boronate ester proceeded without negatively affecting the molecular weight properties and the tacticity of sPS. A macroinitiator suitable for ATRP could be synthesized by the esterification of 2‐bromo‐2‐methylpropionyl bromide and hydroxy‐functionalized sPS. The graft polymerizations of methyl methacrylate and tert‐butyl acrylate from the macroinitiator using ATRP afforded polar block grafted sPS materials, syndiotactic polystyrene‐graft‐poly(methyl methacrylate) (sPS‐g‐PMMA) and syndiotactic polystyrene‐graft‐poly(tert‐butyl acrylate) (sPS‐g‐PtBA). The latter was hydrolyzed to yield an amphiphilic graft copolymer, syndiotactic polystyrene‐graft‐poly(acrylic acid) (sPS‐g‐PAA). The structures of the copolymers were characterized by NMR and FTIR spectroscopies. Size exclusion chromatography and ¹H NMR spectroscopy were used to study any changes in the molecular weight properties from the parent polymer. A decrease in the hydrophobicity of the graft copolymers was confirmed by water contact angle measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6655–6667, 2009     

Synthesis and characterization of luminescent rod-coil block copolymers by atom transfer radical polymerization: utilization of novel end-functionalized terfluorenes as macroinitiators

Two novel, rigid, photoluminescent, substituted terfluorene derivatives were synthesized by utilizing direct bromination and Suzuki coupling reactions. These oligomers were used as initiators for the atom transfer radical polymerization (ATRP) of styrene and tert-butyl acrylate. Thus, diblock and triblock rod-coil block copolymers were prepared with well-defined structure, as far as their size and shape is concerned. Molecular weights up to approximately 21 000 and polydispersity indices not exceeding 1.5 in most cases were obtained. The copolymers emit blue light in solution, and their luminescence properties remain practically invariable when passing from solution to the solid state. No ground-state aggregation or excimer formation were observed in the solid state, even after annealing at high temperatures.     

RAFT法合成两亲性嵌段共聚物PSt-b-PAA-b-PSt及其在离子液体[BMIM][PF_6]中的自组装

用三硫代碳酸二(α,α′-二甲基-α-乙酸)酯(BDATC)作为链转移剂,苯乙烯St作为第一单体,通过可逆加成-断裂链转移聚合(RAFT)方法合成出大分子链转移剂PSt-CTA,以丙烯酸AA作为第二共聚单体合成出3个不同嵌段比的两亲性嵌段共聚物聚苯乙烯-b-聚丙烯酸-b-聚苯乙烯(PSt-b-PAA-b-PSt).通过傅里叶变换红外光谱(FTIR)和核磁共振氢谱(1H-NMR)确定了PSt-b-PAA-b-PSt结构,使用凝胶渗透色谱(GPC)测定了大分子引发剂PSt-CTA和嵌段共聚物PSt-b-PAA-b-PSt的分子量及分子量分布.将这3个不同嵌段比的两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐[BMIM][PF6]中进行自组装,用透射电子显微镜(TEM)观察聚合物在离子液体中自组装结构.研究发现,当PSt的链段长度固定时,胶束的自组装形态主要依赖于PAA链的长度.当PAA链段较长时,胶束呈球形;PAA链段变得较短时,胶束的形态则由球形转变为核壳结构,并且胶束形态在25℃至100℃之间不受温度影响.     

Generation of radical species on polypropylene by alkylborane‐oxygen system and its application to graft polymerization

Graft polymerization of ethyl acrylate and n‐butyl acrylate onto surface of polypropylene (PP) beads (diameter: 3.2 mm) were carried out by using a redox system composed of triethylborane (Et₃B) and molecular oxygen in air. The amounts of the grafted polymers increased by prolonging a period of soaking PP beads in a solution of Et₃B in hexane, a less polar solvent of which affinity with PP would be higher than that of tetrahydrofuran, a highly polar solvent. These results implied that the present graft polymerization involved: (1) interpenetration of Et₃B into the surface area with the aid of hexane as a solvent, (2) its aerobic oxidation to generate a radical species, (3) abstraction of proton from PP by the radical species, and (4) initiation of polymerization from the resulting radical on the PP surface. Besides the acrylates, acrylic acid, and glycidyl methacrylate were also grafted onto the surface of PP to endow it with carboxyl and epoxy moieties, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6163–6167, 2009