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1.
SUN Rui WANG Ying GOU Pengfei ZUO Min LI Xiaodong ZHU Weipu SHEN Zhiquan 《高等学校化学研究》2018,34(1):132-137
Well-defined amphiphilic seven-arm star triblock copolymers containing hydrophobic crystalline poly(ε-caprolactone)(PCL) blocks, hydrophobic non-crystalline poly(tert-butyl acrylate)(PtBA) blocks and hydrophilic poly(ethylene glycol)(PEG) blocks were precisely synthesized by a combination of ring-opening polymerization(ROP), atom transfer radical polymerization(ATRP) and “click” reaction. Such star copolymers could self-assemble into “core-shell-corona” micelles and “multi-layer” vesicles depending on the fraction of each block. Meanwhile, the selective hydrolysis of middle PtBA blocks into the poly(acrylic acid)(PAA) blocks allowed the star block copolymers to further change their morphologies of aqueous aggregates in response to pH values. 相似文献
2.
Aggregative behavior of AB and ABC block copolymers in the solid phase and in a nonselective solvent
D. V. Vishnevetski E. A. Lysenko A. V. Plutalova E. V. Chernikova 《Polymer Science Series A》2016,58(1):1-11
Effects of the amount of chemically dissimilar blocks (two or three) and their polarity on the aggregative behavior of АВ and АВС linear block copolymers of various compositions that are based on polystyrene, poly(n-butyl acrylate), and either poly(acrylic acid) or poly(tert-butyl acrylate) in bulk and in the nonselective solvent DMF are studied via differential scanning calorimetry and dynamic light scattering. АВ block copolymers composed of two chemically dissimilar blocks in the diluted solution in DMF are fully dispersed into macromolecular coils. However, the simultaneous incorporation of three incompatible blocks of different polarities (polystyrene, poly(acrylic acid), and poly(n-butyl acrylate)) into the copolymer is accompanied by a well-defined segregation of blocks in the nonselective solvent, regardless of the composition of the block copolymer and the length and sequence of blocks. This phenomenon makes itself evident as the formation of intermacromolecular aggregates in diluted solutions with a mean hydrodynamic radius of 60–120 nm that are stable in the range 10–60°C. A decrease in the level of the thermodynamic incompatibility of blocks (replacement of a poly(acrylic acid) polar block with a less polar poly(tert-butyl acrylate) block) or the selective improvement of solvent quality with respect to the polar block (the addition of LiBr to DMF) suppresses the segregation of blocks and may lead to the formation of a molecularly dispersed solution of the block copolymer. 相似文献
3.
Koji Ishizu Hideya Katsuhara Kazuo Itoya 《Journal of polymer science. Part A, Polymer chemistry》2006,44(10):3321-3327
(AB)f star block copolymers were synthesized by the radical polymerization of a poly(t‐butyl acrylate)‐block‐poly(methyl methacrylate) diblock macroinitiator with ethylene glycol dimethacrylate in methanol under UV irradiation. Diblock macroinitiators were prepared by diethyldithiocarbamate‐mediated sequential living radical copolymerization initiated by (4‐cyano‐4‐diethyldithiocarbamyl)pentanoic acid under UV irradiation. The arm number (f) was controlled by the variation of the initial concentration of the diblock initiator. It was found from light scattering data that such star block copolymers (f ≥ 344) not only took a spherical shape but also formed a single molecule in solution. Subsequently, we derived amphiphilic [arm: poly(acrylic acid)‐block‐poly(methyl methacrylate)] star block copolymers by the hydrolysis of poly(t‐butyl acrylate) blocks. These amphiphilic star block copolymers were soluble in water because the external blocks were composed of hydrophilic poly(acrylic acid) chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3321–3327, 2006 相似文献
4.
Bing-yi Li Yan Shi Zhi-feng Fu Wan-tai Yang Shu-ke Jiao 《高分子科学》2007,(6):609-619
Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid)were synthesized by iodide- mediated radical polymerization.Firstly,free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate)as chain transfer agent,giving iodine atom ended star-shaped polystyrene with three arm chains,R(polystyrene)_3.Secondly,tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent,and star-block copolymer,R(polystyrene-b-poly(tert-butyl acrylate))_3 with controlled molecular weight was obtained.Finally,amphiphilic star-block copolymer,R(polystyrene-b-poly(acrylic acid))_3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))_3 under acidic condition. 相似文献
5.
Bohumil Masař Miroslav Janata Petr Vlček Petra Polická Luděk Toman 《Macromolecular Symposia》2002,183(1):139-144
Poly(methyl methacrylate)s with terminal bromine atom, prepared by bromination of anionically polymerized MMA, were used as ATRP macroinitiators giving di- and triblock copolymers with MMA, styrene and butyl acrylate blocks. Multifunctional ATRP macroinitiators were synthesized by introducing bromomethyl or 2-bromoacyloxy groups onto the main chain of polystyrene or poly(4-methyl styrene) and used for ATRP grafting of tert-butyl acrylate leading to densely grafted copolymers with more or less uniform grafts. 相似文献
6.
Alexandra Muoz‐Bonilla María L. Cerrada Marta Fernndez‐García 《Journal of polymer science. Part A, Polymer chemistry》2005,43(20):4828-4837
The syntheses of triblock copolymers by the atom transfer radical polymerization of tert‐butyl and iso‐butyl acrylates as inner blocks with cyclohexyl methacrylate as outer blocks are reported. The living behavior and blocking efficiency of these polymerizations were investigated in each case. The use of difunctional macroinitiators led to ABA triblock copolymers with narrow polydispersities and controlled number‐average molecular weights. These copolymers were prepared from bromo‐terminated macroinitiators of poly(tert‐butyl acrylate) and poly(iso‐butyl acrylate), with copper chloride/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalytic system, at 40 °C in 50% (v/v) toluene solutions. The block copolymers were characterized with size exclusion chromatography and 1H NMR spectroscopy. Differential scanning calorimetry measurements were performed to reveal the phase segregation. The glass transition of the inner block was not clearly detected, with the exception of the copolymer synthesized with the longest poly(iso‐butyl acrylate) macroinitiator length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4828–4837, 2005 相似文献
7.
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 总被引:1,自引:0,他引:1
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. 相似文献
8.
A series of polyacrylate‐polystyrene‐polyisobutylene‐polystyrene‐polyacrylate (X‐PS‐PIB‐PS‐X) pentablock terpolymers (X=poly(methyl acrylate) (PMA), poly(butyl acrylate) (PBA), or poly(methyl methacrylate) (PMMA)) was prepared from poly (styrene‐b‐isobutylene‐b‐styrene) (PS‐PIB‐PS) block copolymers (BCPs) using either a Cu(I)Cl/1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) or Cu(I)Cl/tris[2‐(dimethylamino)ethyl]amine (Me6TREN) catalyst system. The PS‐PIB‐PS BCPs were prepared by quasiliving carbocationic polymerization of isobutylene using a difunctional initiator, followed by the sequential addition of styrene, and were used as macroinitiators for the atom transfer radical polymerization (ATRP) of methyl acrylate (MA), n‐butyl acrylate (BA), or methyl methacrylate (MMA). The ATRP of MA and BA proceeded in a controlled fashion using either a Cu(I)Cl/PMDETA or Cu(I)Cl/Me6TREN catalyst system, as evidenced by a linear increase in molecular weight with conversion and low PDIs. The polymerization of MMA was less controlled. 1H‐NMR spectroscopy was used to elucidate pentablock copolymer structure and composition. The thermal stabilities of the pentablock copolymers were slightly less than the PS‐PIB‐PS macroinitiators due to the presence of polyacrylate or polymethacrylate outer block segments. DSC analysis of the pentablock copolymers showed a plurality of glass transition temperatures, indicating a phase separated material. 相似文献
9.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):155-169
ABSTRACT Coil-rod-coil block copolymers composed from luminescent rigid units and acrylate flexible blocks have been synthesized using atom transfer radical polymerization. α,ω-Difunctionalized oligophenylenes properly modified to act as ATRP initiators have been used for the polymerization of the various acrylates. Copolymers with controlled shape and in some cases, relatively low polydispersities have been obtained as proved by size exclusion chromatography and NMR. In cases, where t-butyl acrylate blocks have been used as the flexible part, selective hydrolysis resulted in coil-rod-coil copolymers containing poly(acrylic acid) blocks. The solution behavior of the synthesized copolymers was explored in various solvents. The poly(acrylic acid) copolymers in aqueous solutions form large aggregates, while in organic selective solvents for the flexible block, monomolecular micelles seem to be formed. 相似文献
10.
Catherine Lefay Joël Belleney Bernadette Charleux Olivier Guerret Stphanie Magnet 《Macromolecular rapid communications》2004,25(13):1215-1220
Summary: A low‐molar‐mass poly(acrylic acid) with a narrow molar‐mass distribution, prepared by SG1 nitroxide‐mediated controlled free‐radical polymerization, was subjected to end‐group analysis to confirm its living nature. 1H and 31P NMR spectroscopy confirmed the presence of the SG1‐based alkoxyamine end group. Furthermore, chain extension with styrene and n‐butyl acrylate demonstrated the ability of the homopolymer to initiate the polymerization of a second block. These results open the door to the synthesis of poly(acrylic acid)‐based block copolymers by direct nitroxide‐mediated polymerization of acrylic acid.
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12.
<正>A generic method was described to change surface biocompatibihty by introducing reactive functional groups onto surfaces of polymeric substrates and covalently binding them with biomolecules.A block copolymer with protected carboxylic acid functionality,poly(styrene-b-tert-butyl acrylate)(PS-PtBA),was spin coated from solutions in toluene on a bioinert polystyrene(PS) substrate to form a bilayer structure:a surface layer of the poly(tert-butyl acrylate)(PtBA) blocks that order at the air-polymer interface and a bottom layer of the PS blocks that entangle with the PS substrate.The thickness of the PtBA layer and the area density of tert-butyl ester groups of PtBA increased linearly with the concentration of the spin coating solution until a 2 nm saturated monolayer coverage of PtBA was achieved at the concentration of 0.4%W/W.The protected carboxylic acid groups were generated by exposing the tert-butyl ester groups of PtBA to trifluoroacetic acid (TFA) for bioconjugation with FMRF peptides via amide bonds.The yield of the bioconjugation reaction for the saturated surface was calculated to be 37.1%based on X-ray photoelectron spectroscopy(XPS) measurements.The success of each functionalization step was demonstrated and characterized by XPS and contact angle measurements.This polymer functionalization/modification concept can be virtually applied to any polymeric substrate by choosing appropriate functional block copolymers and biomolecules to attain novel biocompatibility. 相似文献
13.
Rodrigo París José Luis de la Fuente 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3538-3549
Different diblock copolymers constituted by one segment of a monomer supporting a reactive functional group, like allyl methacrylate (AMA), were synthesized by atom transfer radical polymerization (ATRP). Bromo‐terminated polymers, like polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(butyl acrylate) (PBA) were employed as macroinitiators to form the other blocks. Copolymerizations were carried out using copper chloride with N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as the catalyst system in benzonitrile solution at 70 °C. At the early stage, the ATRP copolymerizations yielded well‐defined linear block copolymers. However, with the polymerization progress a change in the macromolecular architecture takes place due to the secondary reactions caused by the allylic groups, passing to a branched and/or star‐shaped structure until finally yielding gel at monomer conversion around 40% or higher. The block copolymers were characterized by means of size exclusion chromatography (SEC), 1H NMR spectroscopy, and differential scanning calorimetry (DSC). In addition, one of these copolymers, specifically P(BA‐b‐AMA), was satisfactorily modified through osmylation reaction to obtain the subsequent amphiphilic diblock copolymer of P(BA‐b‐DHPMA), where DHPMA is 2,3‐dihydroxypropyl methacrylate; demonstrating the feasibility of side‐chain modification of the functional obtained copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3538–3549, 2007 相似文献
14.
Block copolymers of poly(pentafluorostyrene) (PFS) and poly(tert-butyl acrylate) (PtBA), or PFS-b-PtBA copolymers, were synthesized via consecutive atom transfer radical polymerizations (ATRPs). Amphiphilic block copolymers of PFS and poly(acrylic acid) (PFS-b-PAAC copolymers) were prepared via hydrolysis of the corresponding PFS-b-PtBA copolymers. The chemical structure and composition of the PFS-b-PtBA and PFS-b-PAAC block copolymers were studied by nuclear magnetic resonance (NMR) spectroscopy, themogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The amphiphilic PFS-b-PAAC copolymers were cast into porous membranes by phase inversion in aqueous media. The surface and cross-sectional morphology of the PFS-b-PAAC membranes were studied by scanning electron microscopy (SEM). Membranes with well-defined pores of sizes in the micrometer range were obtained as a result of inverse micelle formation. The pH of the aqueous media for phase inversion and the PAAC content in the PFS-b-PAAC copolymers could be used to adjust the pore size of the membranes. 相似文献
15.
O. A. Novoskol’tseva V. D. Astakhova E. V. Chernikova V. B. Rogacheva A. B. Zezin 《Polymer Science Series A》2011,53(12):1141-1149
The interaction of amphiphilic block copolymers comprising an anionic block (polyacrylate or polymethacrylate) and a hydrophobic
block (polystyrene, poly(butyl acrylate) or polyisobutylene) with lightly crosslinked poly(N,N-diallyl-N,N-dimethylammonium chloride) is studied for the first time. It is shown that the cationic hydrogel can sorb anionic amphiphilic
block copolymers via electrostatic interaction with the corona of block copolymer micelles. The rate of sorption of block
copolymer polyelectrolytes is significantly lower than the rate of sorption of linear polyions and is controlled by the lengths
of the hydrophilic and hydrophobic blocks and the flexibility of the latter blocks. The sorption of amphiphilic block copolymers
is accompanied by their self-assembly in the polycomplex gel and formation of a continuous hydrophobic layer impermeable to
water and the low-molecular-mass salt dissolved in it. 相似文献
16.
Design and synthesis of fluorescent shell functionalized polymer micelles for biomedical application
Selen R. Ismail Rayna G. Bryaskova Nikolai I. Georgiev Nikoleta D. Philipova Ventsislav V. Bakov Veselina P. Uzunova Rumiana D. Tzoneva Vladimir B. Bojinov 《先进技术聚合物》2020,31(6):1365-1376
pH‐sensitive polymers can be defined as polyelectrolytes that include in their structure weak acidic or basic groups that either accept or release protons in response to a change in the environmental pH. This work summarizes the design, synthesis, and potential applications of pH‐responsive fluorescent copolymers in the biomedical field. This was achieved using atom transfer radical polymerization (ATRP) of tert‐butyl acrylate using a CuBr/N,N,N′,N″N″‐pentamethyldiethylenetriamine catalyst system in conjunction with an alkyl bromide as the initiator. Well‐defined macroinitiators based on poly(tert‐butyl acrylate) with narrow molecular weight distributions were obtained by the addition of an appropriate solvent system in order to create a homogeneous catalytic system. The addition of n‐butyl acrylate as a second building block in order to create well‐defined poly(tert‐butyl acrylate)‐b‐poly(n‐butyl acrylate) block copolymers (PtBA‐b‐PnBA) followed by chemical modification of the block copolymers and functionalization with an appropriate fluorescent compound are the basis for the preparation of well‐defined fluorescent pH‐sensitive micelles. Thus, prepared water soluble nanosized pH‐sensitive micelles consisting of hydrophobic poly(n‐butyl acrylate) core and hydrophilic polyacrylic acid shell decorated with an appropriate fluorescent compound determined their potential applications of these systems in the field of biomedicine as biosensors, controlled drug delivery systems, and so on. In this respect, the cell viability and internalization of the polymer micelles were studied. 相似文献
17.
Gaël Laruelle Jeanne Franois Laurent Billon 《Macromolecular rapid communications》2004,25(21):1839-1844
Summary: Amphiphilic diblock copolymers consisting of a hydrophilic block, poly(acrylic acid), and a hydrophobic block, polystyrene, were synthesized by direct nitroxide‐mediated polymerization using the PS block as a macro‐initiator for the first time. Several techniques were used to characterize the amphiphilic block copolymers (size exclusion chromatography, NMR spectroscopy). The proposed method can lead to samples with a broad range of composition and molar mass. Preliminary studies of their self‐assembly in aqueous medium using fluorescence spectroscopy and small‐angle neutron scattering are presented.
18.
Delphine Chan‐Seng David A. Rider Gérald Guérin Michael K. Georges 《Journal of polymer science. Part A, Polymer chemistry》2008,46(2):625-635
Living‐radical polymerization of acrylates were performed under emulsion atom transfer radical polymerization (ATRP) conditions using latexes prepared by a nanoprecipitation technique previously employed and optimized for the polymerization of styrene. A macroinitiator of poly(n‐butyl acrylate) prepared under bulk ATRP was dissolved in acetone and precipitated in an aqueous solution of Brij 98 to preform latex particles, which were then swollen with monomer and heated. Various monomers (i.e. n‐butyl acrylate, styrene, and tert‐butyl acrylate) were used to swell the particles to prepare homo‐ and block copolymers from the poly(n‐butyl acrylate) macroinitiator. Under these conditions latexes with a relatively good colloidal stability were obtained. Furthermore, amphiphilic block copolymers were prepared by hydrolysis of the tert‐butyl groups and the resulting block copolymers were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The bulk morphologies of the polystyrene‐b‐poly(n‐butyl acrylate) and poly(n‐butyl acrylate)‐b‐poly(acrylic acid) copolymers were investigated by atomic force microscopy (AFM) and small angle X‐ray scattering (SAXS). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 625–635, 2008 相似文献
19.
Copper(I)-mediated living radical polymerization was used to synthesize a series of self-crosslinkable ABA triblock copolymers in which the side blocks are formed by a monomer supporting a reactive functional group, as allyl methacrylate (AMA). The copolymers were prepared according with a two steps synthetic methodology. In the first step, ,ω-dibromo homopolymers of polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(butyl acrylate) (PBA) were synthesized by atom transfer radical polymerization (ATRP). In the second step, these telechelic polymers were employed as macroinitiators for the ATRP of AMA in benzonitrile solution at 70 °C with CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) as catalyst system in order to obtain well-defined functionalized triblock copolymers. The living nature of the block copolymerizations involved was investigated in each case and a similar general behaviour was found. Thus, the molecular weights increased fairly linearly with the conversion degree with first-order kinetics in respect of monomer until moderate conversions, where secondary reactions become more relevant. Finally, intermacromolecular crosslinking were observed giving macrogels as a unique reaction product. The polymers were characterized by different characterization techniques, such as size exclusion chromatography (SEC), 1H NMR spectroscopy and differential scanning calorimetry (DSC). In addition, the facile thermal crosslinking of these block copolymers was evaluated from rheological measurements. 相似文献
20.
Zhifeng Fu Wuping Tao Yan Shi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(1):362-372
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 相似文献