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1.
The synthesis of amphiphilic dextran‐g‐poly(methyl methacrylate) glycopolymers (Dex‐g‐PMMA) is studied using “grafting from” concept and atom transfer radical polymerization. Two strategies have been examined to control the macromolecular parameters of such glycopolymers. One is involving four steps including a protection/deprotection approach and the second one only two steps. The introduction of initiators group onto a protected acetylated dextran (and directly onto dextran) was achieved resulting in protected DexAcBr (and in unprotected DexBr). These two types of polysaccharidic macroinitiators differ in term of solubility (hydrophilic DexBr vs. hydrophobic DexAcBr) and of position of the initiators groups on the glucosidic units (which are the sites of the future grafts). When evaluated as macroinitiators for ATRP of MMA, control was achieved in both cases but DexBr gave much faster polymerization and lower average grafting efficiency compared with DexAcBr or model initiator. Advantages and drawbacks of both pathways have finally been discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010  相似文献   

2.
Poly(vinyl amine) (PVAm)‐based amphiphilic glycopolymers were synthesized by a two‐step method, that is dextran molecules (Dex, Mw = 1500) were attached to the PVAm backbone by reacting amine groups with dextran lactone, and then, hexanoyl groups (Hex) were attached by reacting the PVAm free amine groups with N‐(hexanoyloxy)succinimide. By adjustment of the feed ratios of Dex/Hex, amphiphilic comb‐like glycopolymers with various hydrophilic and hydrophobic balances were prepared, and their structures were characterized by 1H NMR. Surface activity of the amphiphilic glycopolymers at the air/water interface was demonstrated by reduction in water surface tension. Adsorption of the amphiphilic glycopolymers at the solid/water interface was examined on octadecyltrichlorosilane (OTS)‐coated coverslips by water contact angle measurements. The results show that the amphiphilic glycopolymers need about 20 mol % of dextran attachment to make an effective hydrophilic coating. In comparison with the one‐step reaction by addition of dextran lactone and alkyl succinimide simultaneously, the two‐step approach can attach Dex on PVAm as high as possible in the first step, and offers quantitative advantages in controlling the ratio of hydrophilic and hydrophobic chains along the PVAm backbone, resulting in increased water solubility for the final amphiphilic glycopolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 192–199, 2006  相似文献   

3.
The whole controlled synthesis of novel amphiphilic polylactide (PLA)‐grafted dextran copolymers was achieved. The control of the architecture of such biodegradable and potentially biocompatible copolymers has required a three‐step synthesis based on the “grafting from” concept. The first step consisted of the partial silylation of the dextran hydroxyl groups. This protection step was followed by the ring‐opening polymerization of D ,L ‐lactide initiated from the remaining OH functions of the partially silylated polysaccharide. The third step involved the silylether group deprotection under very mild conditions. Based on previous studies, in which the control of the first step was achieved, this study is focused on the last two steps. Experimental conditions were investigated to ensure a controlled polymerization of D ,L ‐lactide, in terms of grafting efficiency, graft length, and transesterification limitation. After polymerization, the final step was studied in order to avoid degradation of both polysaccharide backbone and polyester grafts. The chemical stability of dextran backbone was checked throughout each step of the synthesis. PLA‐grafted dextrans and PLA‐grafted (silylated dextrans) were proved to adopt a core‐shell conformation in various solvents. Furthermore, preliminary experiments on the potential use of these amphiphilic grafted copolymers as liquid/liquid interface stabilizers were performed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2577–2588, 2004  相似文献   

4.
Novel multigraft copolymers of poly(methyl methacrylate‐graft‐polystyrene) (PMMA‐g‐PS) in which the number of graft PS side chains was varied were prepared by a subsequent two‐step living radical copolymerization approach. A polymerizable 4‐vinylbezenyl 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) monomer (STEMPO), which functioned as both a monomer and a radical trapper, was placed in a low‐temperature atom transfer radical polymerization (60°C) process of methyl methacrylate with ethyl 2‐bromopronionate (EPNBr) as an initiator to gain ethyl pronionate‐capped prepolymers with TEMPO moieties, PMMA‐STEMPOs. The number of TEMPO moieties grafted on the PMMA backbone could be designed by varying STEMPO/EPNBr, for example, the ratios of 1/2, 2/3, or 3/4 gained one, two, or three graft TEMPO moieties, respectively. The resulting prepolymers either as a macromolecular initiator or a trapper copolymerized with styrene in the control of stable free‐radical polymerization at an elevated temperature (120 °C), producing the corresponding multigraft copolymers, PMMA‐g‐PSs. The nitroxyl‐functionalized PMMA prepolymers produced a relatively high initiation efficiency (>0.8) as a result of the stereohindrance and slow diffusion of TEMPO moieties connected on the long PMMA backbone. The polymerization kinetics in two processes showed a living radical polymerization characteristic. The molecular structures of these prepolymers and graft copolymers were well characterized by combining Fourier transform infrared spectroscopy, gel permeation chromatography, chemical element analysis, and 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1876–1884, 2002  相似文献   

5.
Polymeric films with porous structures and microsphere patterns were prepared by the method of breath figures, mixing poly(methyl methacrylate) (PMMA) and amphiphilic copolymers containing glucose moieties in their structure, glycopolymers. Statistical and block glycopolymers were used in a proportion of 10 wt %. The statistical glycopolymers were synthesized via conventional free radical copolymerization, whereas the block copolymer of methyl methacrylate and 2‐{[(D ‐glucosamin‐2‐Nyl) carbonyl]oxy}ethyl methacrylate, PMMA‐b‐PHEMAGl, was obtained by atom transfer radical polymerization. Glycopolymers were blended with a high molecular weight PMMA matrix and dissolved in a mixture of tetrahydrofuran and a small amount of water. Results showed that, depending on experimental conditions (water content, humidity, and type of copolymer), the observed final film morphology changes significantly. Thus, films with honeycomb pattern structures, spherical particles, or a mixture of both were obtained. In addition, polar glucose moieties were oriented principally either inside of the pores in the case of films and towards the surface in the case of particles. The specific surface bioactivity of these materials was examined using the specific lectin concanavalin A conjugated with fluorescein, Con A‐FITC. The successful binding of the Con A was demonstrated by fluorescence microscopy being more intense at the surface of the pores and of the particles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

6.
Methacrylic acid (MAA), methyl methacrylate (MMA), methacrylamide, and oligomers of MAA and MMA were selected as a model of active radical species in living template polymerization using stereocomplex formation. The adsorption behaviors of the aforementioned model compounds were examined toward porous isotactic‐(it‐) poly(methyl methacrylate) (PMMA) ultrathin films on a quartz crystal microbalance, which was prepared by the extracting of syndiotactic‐(st‐) poly(methacrylic acid) (PMAA) from it‐PMMA/st‐PMAA stereocomplexes. The apparent predominant adsorption of oligomers to monomers was observed in both PMAA and PMMA oligomers, suggesting that the mechanism of template polymerization follows the pick up mechanism. Although vinyl monomers were not incorporated into the porous it‐PMMA ultrathin film, both PMMA and PMAA oligomers were adsorbed at the initial stages. However, adsorbed amounts were limited to about 5 and 15% at 0.1 mol L?1, respectively, which are much smaller values than corresponding st‐polymers. The results imply that radical coupling reaction is prevented during template polymerization to support the resulting living polymerization. ATR‐IR spectral patterns of oligomer complexes and it‐PMMA slightly changed in both cases, suggesting complex formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5879–5886, 2008  相似文献   

7.
Graft copolymers with cellulose diacetate (CDA) backbone and both the poly(ε‐caprolactone) and polystyrene, or poly(butyl acrylate) or PMMA grafts were prepared by two‐step process. First, ε‐caprolactone (CL) was polymerized by ring‐opening polymerization (ROP) initiated with CDA, partly funcionalized with 2‐bromo‐isobutyryl groups (degree of functionalization was 0.5). The p(CDA‐g‐CL) copolymers were used in the second step as polyfunctional macroinitiators of ATRP of the vinyl monomer, giving densely grafted copolymers with polyester and PSt, or PBuA, or PMMA grafts. The prepared copolymers were characterized by SEC, some of them also by FTIR spectroscopy and atomic force microscopy (AFM). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 564–573, 2008  相似文献   

8.
The synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at ?78 °C in the presence of LiClO4. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The 1H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The 1H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using 1H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008  相似文献   

9.
In this study, graft copolymers with regular graft points containing polystyrene (PS) backbone and poly(methyl methacrylate) (PMMA), poly(tert‐butyl acrylate) (PtBA), or poly (ethylene glycol) (PEG) side chains were simply achieved by a sequential double polymer click reactions. The linear α‐alkyne‐ω‐azide PS with an anthracene pendant unit per chain was produced via atom transfer radical polymerization of styrene initiated by anthracen‐9‐ylmethyl 2‐((2‐bromo‐2‐methylpropanoyloxy)methyl)‐2‐methyl‐3‐oxo‐3‐(prop‐2‐ynyloxy) propyl succinate. Subsequently, the azide–alkyne click coupling of this PS to create the linear multiblock PS chain with pendant anthracene sites per PS block, followed by Diels–Alder click reaction with maleimide end‐functionalized PMMA, PtBA, or PEG yielded final PS‐g‐PMMA, PS‐g‐PtBA or PS‐g‐PEG copolymers with regular grafts, respectively. Well‐defined polymers were characterized by 1H NMR, gel permeation chromatography (GPC) and triple detection GPC. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

10.
A modular approach for the synthesis of graft copolymers by the combination of reversible addition–fragmentation chain‐transfer (RAFT) polymerization and photoinduced acylation processes is described. In the two‐step approach, first the copolymers of benzodioxinone containing monomer, namely, 4‐oxo‐2,2‐diphenyl‐4H‐benzo[d][1,3]dioxin‐7‐yl methacrylate (BDMA) and methyl methacrylate (MMA) in different feed ratios were prepared by RAFT polymerization. In the subsequent step, dichloromethane solutions of these copolymers (PMMA‐co‐PBDMA) were irradiated at λ = 300 nm in the presence of independently prepared hydroxyl functional polymers such as poly(ethylene glycol) (MeO‐PEG‐OH) and poly(?‐caprolactone) (PCL‐OH). Side‐chain esterification reaction between photochemically generated ketene groups and hydroxyl functionalities resulted in the formation graft copolymers. The intermediates and final graft copolymers were characterized by 1H NMR, UV, IR, fluorescence, and GPC measurements. The success of the process was also confirmed by a model reaction using pyrene methanol. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 274–280  相似文献   

11.
The syntheses of a variety of amphiphilic block glycopolymers based on 2‐{[(D ‐glucosamin‐2‐N‐yl)carbonyl]oxy}ethyl acrylate and n‐butyl acrylate or methyl methacrylate by single‐electron transfer‐living radical polymerization (SET‐LRP) are described. In a first step, the homopolymerization of unprotected acrylic glycomonomer to obtain well‐controlled glycopolymers is studied. Posterior and based on these studies, di‐ and triblock glycopolymers were synthesized via SET‐LRP of the glycomonomer from different hydrophobic blocks, varying the hydrophilic block lengths. All the copolymers are characterized by nuclear magnetic resonance spectroscopy and GPC. Moreover, their water solution behavior by dynamic light scattering and their capacity of interaction with Concanavalin A lectin by turbidimetry are analyzed. The effect on the block glycopolymers behavior of hydrophobic block nature and the length of glycopolymer segments is evaluated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013  相似文献   

12.
A series of random copolymers, composed of 1H,1H‐perfluorooctyl methacrylate (FOMA) and 2‐dimethylaminoethyl methacrylate (DMAEMA) were prepared as stabilizers for the dispersion polymerization of methyl methacrylate in supercritical CO2 (scCO2). Free‐flowing, spherical poly(methyl methacrylate) (PMMA) particles were produced in high yield by the effective stabilization of poly(FOMA‐co‐DMAEMA) containing 34–67 w/w % (15–41 m/m %) FOMA structural units. Less stabilized but micron‐sized discrete particles could be obtained even with 25 w/w % (10 m/m %) FOMA stabilizer. The result showed that the composition of copolymeric stabilizers had a dramatic effect on the size and morphology of PMMA. The particle size was controllable with the surfactant concentration. The effect of the monomer concentration and the initial pressure on the polymerization was also investigated. The dry polymer powder obtained from dispersion polymerization could be redispersed to form stable aqueous latexes in an acidic buffered solution (pH = 2.1) by an electrostatic stabilization mechanism due to the ionization of DMAEMA units in the stabilizer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1365–1375, 2008  相似文献   

13.
This study elucidates the influence of the atom transfer radical polymerization initiator structure, monolayer versus disordered multilayer, on the growth kinetics and the structural transition of poly(methyl methacrylate) (PMMA) brush layers. The multilayer initiator film, prepared by acylation of the electrografted 2‐phenylethanol layer using 2‐bromoisobutyryl bromide, consists of ~4.6 times more tert‐butyl bromide groups compared to monolayer initiator prepared by self assembly technique. The results demonstrate the formation of precursor complex between CuI catalyst and the bromine initiator as a prerequisite step before the onset of polymerization. Furthermore, the PMMA brushes formed by the polymerization from the multilayered initiator layer at 50 °C are 20‐fold thicker compared to the polymerization at 25 °C due to the swelling of the multilayered initiator film. In contrast, the thickness of the PMMA layer on the monolayer initiator is less affected by the polymerization temperature. By varying the initiator density on the surface, the solvent content in the PMMA layer is shown to vary from 15% to 94%, resulting in the transition from concentrated over semidiluted to diluted brushes. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

14.
Graft and star copolymers having poly(methacrylate) backbone and ethylene–propylene random copolymer (EPR) branches were successfully synthesized by radical copolymerization of an EPR macromonomer with methyl methacrylate (MMA). EPR macromonomers were prepared by sequential functionalization of vinylidene chain‐end group in EPR via hydroalumination, oxidation, and esterification reactions. Their copolymerizations with MMA were carried out with monofunctional and tetrafunctional initiators by atom transfer radical polymerization (ATRP). Gel‐permeation chromatography and NMR analyses confirmed that poly(methyl methacrylate) (PMMA)‐g‐EPR graft copolymers and four‐arm (PMMA‐g‐EPR) star copolymers could be synthesized by controlling EPR contents in a range of 8.6–38.1 wt % and EPR branch numbers in a range of 1–14 branches. Transmission electron microscopy of these copolymers demonstrated well‐dispersed morphologies between PMMA and EPR, which could be controlled by the dispersion of both segments in the range between 10 nm and less than 1 nm. Moreover, the differentiated thermal properties of these copolymers were demonstrated by differential scanning calorimetry analysis. On the other hand, the copolymerization of EPR macromonomer with MMA by conventional free radical polymerization with 2,2′‐azobis(isobutyronitrile) also gave PMMA‐g‐EPR graft copolymers. However, their morphology and thermal property remarkably differed from those of the graft copolymers obtained by ATRP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5103–5118, 2005  相似文献   

15.
Heteroarm H‐shaped terpolymers, (polystyrene)(poly(methyl methacrylate))‐ poly(tert‐butyl acrylate)‐(polystyrene)(poly(methyl methacrylate)), (PS)(PMMA)‐PtBA‐(PMMA)(PS), and, (PS)(PMMA)‐poly(ethylene glycol)(PEG)‐(PMMA)(PS), through click reaction strategy between PS‐PMMA copolymer (as side chains) with an alkyne functional group at the junction point and diazide end‐functionalized PtBA or PEG (as a main chain). PS‐PMMA with alkyne functional group was prepared by sequential living radical polymerizations such as the nitroxide mediated (NMP) and the metal mediated‐living radical polymerization (ATRP) routes. The obtained H‐shaped polymers were characterized by using 1H‐NMR, GPC, DSC, and AFM measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1055–1065, 2007  相似文献   

16.
Poly[2‐(dimethylamino) ethyl methacrylate] (PDMAEMA) brushes on the surfaces of clay layers were prepared by in situ free‐radical polymerization. Poly (methyl methacrylate) (PMMA) colloid particles stabilized and initiated by clay layers with PDMAEMA polymer brushes were prepared by Pickering emulsion polymerization. Transmission electron microscopy was used to characterize the structure and morphology of the colloid particles. The X‐ray diffraction (XRD) results indicated that the intercalated structures of the clay layers were almost destroyed in Pickering emulsion polymerization, and clay layers with exfoliated structures were created. The surface of the colloid particles was analyzed by using X‐ray photoelectron spectroscopy (XPS). The XPS results provide direct evidence that the clay layers with PDMAEMA chains cover the PMMA colloid particles. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2632–2639, 2008  相似文献   

17.
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  相似文献   

18.
The poly(HEMA‐co‐MMA‐g‐PMMA) graft copolymer was prepared with a poly(methyl methacrylate) (PMMA) macromonomer, 2‐hydroxyethyl methacrylate (HEMA), and methyl methacrylate (MMA), and its application as a dispersant for the nonaqueous phase dispersion polymerization of polystyrene (PST) was investigated. Monodisperse PST particles were obtained with two‐dimensionally tailored graft copolymers, with the number of grafted chains controlled and the polar component (HEMA) in the backbone chains balanced. As for the reactor, a stirred vessel with moderate agitation yielded uniform polymer particles, whereas sealed glass ampules with an overturning motion yielded broader size distributions. Increasing the polarity of the solvent in the continuous phase yielded smaller polymer particles with a gradual deterioration of monodispersity. Uniform polymer particles with a coefficient of variation of less than 6% were obtained up to 30 wt % solid contents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1788–1798, 2003  相似文献   

19.
A novel heterofunctional initiator, synthesized from pentaerythritol in a three step reaction sequence with two ring opening polymerization (ROP) and two atom transfer radical polymerization (ATRP) initiating sites, was used to prepare A2B2 miktoarm star copolymers of poly(ε‐caprolactone), PεCL, with polystyrene, PS, poly(methyl methacrylate), PMMA, poly(dimethylaminoethyl methacrylate), PDMAEMA, and poly(2‐hydroxyethyl methacrylate), PHEMA. A2B miktoarm stars, A being PεCL or poly(δ‐valerolactone), PδVL and B PS were also prepared from ω,ω‐dihydroxy‐PS, synthesized from ω‐Br‐PS and serinol, by ROP of εCL or δVL. All polymers were characterized by size exclusion chromatography, 1H NMR spectroscopy, and membrane osmometry. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5164–5181, 2007  相似文献   

20.
Linear triblock terpolymers of poly(n‐butyl methacrylate)‐b‐poly(methyl methacrylate)‐b‐poly(2‐fluoroethyl methacrylate) (PnBMA‐PMMA‐P2FEMA) were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization. Kinetic studies of the homopolymerization of 2FEMA by RAFT polymerization demonstrated controllable characteristics with fairly narrow polydispersities (~1.30). The resultant PnBMA‐PMMA‐P2FEMA triblock terpolymers were characterized via 1H NMR, 19F NMR, and gel permeation chromatography. These polymers formed micellar aggregates in a selective solvent mixture. The as‐formed micelles were analyzed using scanning electron microscopy and dynamic light scattering. It was found that these terpolymers could directly self‐organize into complex micelles in a tetrahydrofuran/methanol mixture with diameters that depended on polymer composition. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

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