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1.
Narrow‐distribution, well‐defined comb‐like amphiphilic copolymers are reported in this work. The copolymers are composed of poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) (P(MMA‐co‐HEMA)) as the backbones and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) as the grafted chains, with the copolymer backbones being synthesized via atom‐transfer radical polymerization (ATRP) and the grafted chains by oxyanionic polymerization. The copolymers were characterized by gel permeation chromatography (GPC), Fourier‐transform infrared (FT‐IR) spectroscopy and 1H NMR spectroscopy. The aggregation behavior in aqueous solutions of the comb‐like amphiphilic copolymers was also investigated. 1H NMR spectroscopic and surface tension measurements all indicated that the copolymers could form micelles in aqueous solutions and they possessed high surface activity. The results of dynamic light scattering (DLS) and scanning electron microscopy (SEM) investigations showed that the hydrodynamic diameters of the comb‐like amphiphilic copolymer aggregates increased with dilution. Because of the protonizable properties of the graft chains, the surface activity properties and micellar state can be easily modulated by variations in pH. Copyright © 2004 Society of Chemical Industry  相似文献   

2.
Well‐defined methyl methacrylate (MMA) and 2‐(trimethylsiloxy)ethyl methacrylate (Pro‐HEMA) copolymers were prepared by atom‐transfer radical polymerization(ATRP), using CuCl/2,2′‐bipyridine as catalytic system and p‐toluenesulfonyl chloride as initiator. ATRP process of MMA and Pro‐HEMA was monitored by 1H NMR, and the kinetic curves of the MMA/Pro‐HEMA copolymerization were plotted in terms of the 1H NMR data. At low content of Pro‐HEMA in the feed composition, the copolymerization can be well controlled with the molecular weight, polydispersity and the monomer distribution in the copolymer chain. With the increase of Pro‐HEMA content in the feed mixture, the composition of the final copolymer deviates from the composition of the feed mixture gradually, and gradient copolymers of MMA/Pro‐HEMA can be obtained. Through the hydrolysis process, well‐defined copolymers of MMA/HEMA were obtained from poly(MMA/Pro‐HEMA). Copyright © 2003 Society of Chemical Industry  相似文献   

3.
Thermosensitive copolymers of poly(N‐isopropyl acrylamide)‐co‐2‐hydroxyethyl methacrylate (NIPA‐co‐HEMA) macroporous resins were synthesized in the form of beads by inverse suspension polymerization. The copolymerization was carried out in aqueous solutions of the comonomers dispersed by cyclohexane with stabilizers. A series of resins with different molar ratios of NIPA : HEMA, and different crosslinking degrees was obtained. The compositions of the copolymers were determined by elemental analysis. The results showed that the content of HEMA in a copolymer was higher than that of the corresponding feed mixture from which the copolymer was made. IR spectra also confirmed the structure of the copolymers. The porous parameters such as true densities, apparent densities, pore volumes, and porosities of the resins were measured by means of pycnometry. The determination of equilibrium swelling ratios and measurement of differential scanning calibration indicated that the resins exhibited thermosensitivity in aqueous solutions. Finally, the loading of hydroxyl groups was determined by titration. The resins have potential applications as supports in solid‐phase synthesis after being functionalized. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1792–1797, 2004  相似文献   

4.
In this study, synthesis, characterization, partial hydrolysis, and salt formation of poly(2‐hydroxyethyl methacrylate)‐co‐poly(4‐vinyl pyridine), (poly(HEMA)‐co‐poly‐(4‐VP)) copolymers were investigated. The copolymers were synthesized by free radical polymerization using K2S2O8 as an initiator. By varying the monomer/initiator ratio, chain lengths of the copolymers were changed. The copolymers were characterized by gel permeation chromatography (GPC), viscosity measurements, 1H and 13C NMR and FTIR spectroscopies, elemental analysis, and end group analysis methods. The copolymers were partially hydrolyzed by p‐toluene sulfonic acid monohydrate (PTSA·H2O) and washed with LiOH(aq) solution to prepare electrorheological (ER) active ionomers, poly(Li‐HEMA)‐co‐poly(4‐VP). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3540–3548, 2006  相似文献   

5.
Poly(N‐isopropylacrylamide‐co‐hydroxyethyl methacrylate) [P(NIPAM‐co‐HEMA)] copolymer was synthesized by controlled radical polymerization from respective N‐isopropylacrylamide (NIPAM) and hydroxyethyl methacrylate (HEMA) monomers with a predetermined ratio. To prepare the thermosensitive and biodegradable nanoparticles, new thermosensitive graft copolymer, poly(L ‐lactide)‐graft‐poly(N‐isoporylacrylamide‐co‐hydroxyethyl methacrylate) [PLLA‐g‐P(NIPAM‐co‐HEMA)], with the lower critical solution temperature (LCST) near the normal body temperature, was synthesized by ring opening polymerization of L ‐lactide in the presence of P(NIPAM‐co‐HEMA). The amphiphilic property of the graft copolymers was formed by the grafting of the PLLA hydrophobic chains onto the PNIPAM based hydrophilic backbone. Therefore, the graft copolymers can self‐assemble into uniformly spherical micelles ò about 150–240 nm in diameter as observed by the field emission scanning electron microscope and dynamic light scattering. Dexamethasone can be loaded into these nanostructures during dialysis with a relative high loading capacity and its in vitro release depends on temperature. Above the LCST, most of the drugs were released from the drug‐loaded micelles, whereas a large amount of drugs still remains in the micelles after 48 h below the LCST. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

6.
The purpose of this investigation was to prepare by bulk polymerization six new isocyanatoacrylate copolymers and to characterize them. The isocyanatoacrylate copolymers, which were prepared by tri‐n‐butylborane oxide (TBBO)‐initiated free‐radical polymerization, were formed from 1 : 1 mol mixtures of 2‐isocyanatoethyl methacrylate (IEM) with 2‐hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), 2‐hydroxyethyl thiomethacrylate (HETMA), ethylthioethyl methacrylate (ETEMA), 2‐(acetoxyacetoxy)ethyl methacrylate (AAEMA), and tetrahydrofurfuryl methacrylate (THFMA). These six copolymers were compared to the homopolymer of IEM, which was polymerized in an identical fashion. The bulk polymers were fractionated into their acetone‐soluble and acetone‐insoluble components. Physical characterization via photoacoustic infrared (PASIR) spectroscopy showed vast differences in residual isocyanate content. Differential scanning calorimetry (DSC) thermal analysis was carried out on all polymers. Elemental analysis (nitrogen) determined the ratio of IEM to the comonomer and boron analysis showed whether the initiator stayed in the acetone‐insoluble fraction or was “extracted” into the acetone‐soluble fraction. In conclusion, we found that the composition of the copolymers correlated well with the predicted design. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1577–1583, 1999  相似文献   

7.
Diblock copolymers, poly[(10‐hydroxydecanoic acid)‐block‐styrene] (PHDA‐b‐PSt), were synthesized by combining enzymatic condensation polymerization of HDA and atom transfer radical polymerization (ATRP) as of St PHDA was first obtained via enzymatic condensation polymerization catalyzed by Novozyme‐435. Subsequently, one terminus of the PHDA chains was modified by reaction with α‐bromopropionyl bromide and the other terminus was protected by chlorotrimethylsilane. The resulting monofunctional macroinitiator was used subsequently in ATRP of St using CuCl/2,2′‐bipyridine as the catalyst system to afford diblock copolymers including biodegradable PHDA blocks and well‐defined PSt blocks. Polymeric nanospheres were prepared by self‐assembly of the PHDA‐b‐PSt diblock copolymers in aqueous medium. Copyright © 2008 Society of Chemical Industry  相似文献   

8.
《国际聚合物材料杂志》2012,61(11):1001-1008
ABSTRACT

In this study, acrylic acid–based superabsorbent copolymers were synthesized with different comonomers (PEGs) by inverse suspension polymerization technique. The said superabsorbent copolymers were obtained from the aqueous solution of monomers dispersed in a continuous organic phase. The inverse suspension polymerization was accomplished by the use of aqueous solutions of partly neutralized acrylic acid with a predetermined crosslinker agent/monomer ratio in cyclohexane. Sorbitan monostearate was used as a surfactant, ethylene glycol dimethacrylate (EGDM) either as a comonomer or a crosslinking agent, potassium persulfate as the initiator, and polyethylene glycols (PEG 200, PEG 1000, PEG 4000) were used as pore-making agents. The copolymers (SAPs) were characterized by IR spectroscopy and SEM micrographs. Effect of PEGs on the water absorption capacity, rate of absorption to reach equilibrium, and the time needed to release the water absorbed from the gels were investigated. It was observed that the copolymer based on EGDM-Na acrylate + PEG4000 (A3) gave better results than the other copolyemrs.  相似文献   

9.
Well‐defined polystyrene (PS)‐b‐poly(ethylene oxide) (PEO)‐b‐PS triblock copolymers were synthesized by atom‐transfer radical polymerization (ATRP), using C—X‐end‐group PEO as macroinitiators. The triblock copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The experimental results showed that the polymerization was controlled/living. It was found that when the number‐average molecular weight of the macroinititors increased from 2000 to 10,000, the molecular weight distribution of the triblock copolymers decreased roughly from 1.49 to 1.07 and the rate of polymerization became much slower. The possible polymerization mechanism is discussed. According to the Cu content measured with atomic absorption spectrometry, the removal of catalysts, with CHCl3 as the solvent and kaolin as the in situ absorption agent, was effective. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2882–2888, 2000  相似文献   

10.
The introduction of peroxycarbonate groups onto a silica surface and the graft polymerization of vinyl monomers initiated by peroxycarbonate groups introduced onto a silica surface were investigated. The introduction of peroxycarbonate groups onto a silica surface was achieved by Michael addition of amino groups introduced onto the silica surface to t‐butylperoxy‐2‐methacryloyloxyethylcarbonate (HEPO). The amount of peroxycarbonate groups was determined to be 0.17 mmol/g. The graft polymerization of various vinyl monomers such as styrene (St), N‐vinyl‐2‐pyrrolidinone (NVPD), and 2‐hydroxyethyl methacrylate (HEMA) was initiated by peroxycarbonate groups introduced onto the silica surface to give the corresponding polymer‐grafted silicas. The percentage of poly(St)‐grafting reached about 120% after 5 h. This means that 1.20 g of poly(St) is grafted onto 1.0 g of silica. The surface of poly(St)‐grafted silica shows a hydrophobic nature, but the surfaces of poly(NVPD) and poly(HEMA)‐grafted silica show a hydrophilic nature. Furthermore, the poly(St)‐grafted silica was found to give a stable colloidal dispersion in a good solvent for the grafted polymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1491–1497, 1999  相似文献   

11.
The poly(l ‐lactide)‐b‐poly(ethylene glycol)‐b‐poly(l ‐lactide) block copolymers (PLLA‐b‐PEG‐b‐PLLA) were synthesized in a toluene solution by the ring‐opening polymerization of 3,6‐dimethyl‐1,4‐dioxan‐2,5‐dione (LLA) with PEG as a macroinitiator or by transterification from the homopolymers [polylactide and PEG]. Two polymerization conditions were adopted: method A, which used an equimolar catalyst/initiator molar ratio (1–5 wt %), and method B, which used a catalyst content commonly reported in the literature (<0.05 wt %). Method A was more efficient in producing copolymers with a higher yield and monomer conversion, whereas method B resulted in a mixture of the copolymer and homopolymers. The copolymers achieved high molar masses and even presenting similar global compositions, the molar mass distribution and thermal properties depends on the polymerization method. For instance, the suppression of the PEG block crystallization was more noticeable for copolymer A. An experimental design was used to qualify the influence of the catalyst and homopolymer amounts on the transreactions. The catalyst concentration was shown to be the most important factor. Therefore, the effectiveness of method A to produce copolymers was partly due to the transreactions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40419.  相似文献   

12.
The random copolymers (HO‐P(St‐r‐MMA)‐COOH) of styrene (St) and methyl methacrylate (MMA) with hydroxyl group at one end and carboxyl group at another end were synthesized by nitroxide‐mediated living radical polymerization initiated by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and 4‐hydroxyl‐2,2,6,6–tetramethylpiperidineoxyl (TEMPO‐OH). The experimental results have shown that all synthesized copolymers have narrow molecular weight distribution. The conversion of monomers and the molecular weight of copolymer increase with polymerization time. Thus, a copolymerization mechanism containing living radical polymerization is suggested. The use of this method permits the copolymer with two functional chain ends and controllable molecular weight as well as low molecular weight distribution. X‐ray photoelectron spectroscopy result shows that the synthesized copolymers can be tethered on the surface of silicon wafer through the reaction between the hydroxyl end of the copolymer and native oxide layer on the wafer. In addition, an organic/inorganic hybrid surface has achieved by treating copolymer tethered Si‐substrates with SiCl4 vapor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3118–3122, 2006  相似文献   

13.
Water‐soluble polyphenol‐graft‐poly(ethylene oxide) (PPH‐g‐PEO) copolymers were prepared using grafting‐through methodology. Polyphenol chains were synthesized via enzymatic polymerization of phenols, and the graft chains were synthesized via living anionic polymerization of ethylene oxides. The polymers were characterized using gel permeation chromatography, static light scattering and 1H NMR, infrared and ultraviolet spectroscopies. The PPH‐g‐PEO graft copolymers are soluble in several common solvents, such as water, ethanol, N,N‐dimethylformamide, tetrahydrofuran and methylene dichloride. The solubility of the PPH‐g‐PEO graft copolymers is improved significantly compared with that of polyphenol. Copyright © 2009 Society of Chemical Industry  相似文献   

14.
Uniform macroporous particles carrying hydroxyl groups have been obtained in the size range 3–11.5 µm by seeded polymerization. For this purpose, uniform polystyrene particles in the size range 1.9–6.2 µm were used as seeds. The seed particles were successively swollen by dibutyl phthalate (DBP) and a monomer mixture comprising styrene, 2‐hydroxyethylmethacrylate (HEMA) and a crosslinker. Two different crosslinkers, divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA), were tested. Size distribution properties together with bulk and surface structures of the particles have been characterized by both scanning and transmission electron microscopy. While EGDMA provides uniform particles with a non‐porous surface, DVB produces uniform particles having a highly porous surface and interior. The comparison of FTIR and FTIR‐DRS spectra shows that the HEMA concentration is higher on the particle surface than within the particle interior. Seed latex size and monomer/seed latex ratios are identified as the most important variables affecting the final particles. Different seed latexes have been tried; the result is that highly macroporous particles with a sponge‐like pore structure both on the surface and in the particle interior have been obtained by use of the seed latex with the largest particles and the lowest molecular weight. An increase in the HEMA feed concentration leads to final particles with a non‐porous surface and a crater‐like porosity in the particle interior. The average pore size significantly decreases with increasing DBP/seed latex and monomer/seed latex ratios. © 2001 Society of Chemical Industry  相似文献   

15.
A series of aliphatic poly(carbonate‐co‐phosphate)s was synthesized in bulk using aluminium isopropoxide as initiator by ring‐opening polymerization with various cyclic carbonates (trimethylene carbonate (TMC) and 5,5‐dimethyltrimethylene carbonate (DTC)) and cyclic phosphates (ethylene ethyl phosphate (EEP), ethylene isobutyl phosphate (EIBP), ethylene lauryl phosphate (ELP) and ethylene stearyl phosphate (ESP)). The influence of reaction conditions such as polymerization time, polymerization temperature and initiator concentration on the yield and molecular weight were investigated. The substituent effect of the cyclic monomers on the polymerization was also studied, and the results indicate that the substituents exert a marked influence on the molecular weight of the copolymers obtained. The comonomer reactivity ratios were determined (TMC 0.88 and EEP 1.17). The copolymers with backbone chains rich in phosphate content exhibit better hydrophilicity than that of TMC homopolymer, and the degradation rate of the copolymers increases with the increase of phosphate content therein. © 2001 Society of Chemical Industry  相似文献   

16.
The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2‐hydroxyethyl methacrylate) (pHEMA) to which N‐methacryloylhistidine (MAH) was copolymerized. The metal‐complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA‐MAH) beads had a specific surface area of 17.6 m2/g. The synthesized MAH monomer was characterized by NMR; p(HEMA‐MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA‐MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i. e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10–750 mg/L) and at different pH values (3.0–7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA‐MAH) beads were 122.7 mg/g for Cu(II), 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1 234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO3 with high effectiveness. These features make p(HEMA‐MAH) beads a potential candidate for heavy metal removal at high capacity.  相似文献   

17.
pH‐responsive polyethylene terephthalate (PET) track‐etched membranes were synthesized by grafting 2‐hydroxyethyl‐methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH‐responsive characteristics of PET‐g‐poly(2‐hydroxyethyl‐methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH‐response permeation to environmental pH values. Desired pH‐responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40912.  相似文献   

18.
A novel amine methacrylate monomer trimethylolpropane trimethacrylate–piperazine–ethyleneglycol dimethacrylate (TMPTMA‐PPZ‐EGDMA) was synthesized by amination of trimethylolpropane trimethacrylate (TMPTMA) with excess of piperazine (PPZ) followed by reaction with ethyleneglycol dimethacrylate (EGDMA). Copolymerization of TMPTMA‐PPZ‐EGDMA with 2‐hydroxyethyl methacrylate (HEMA) was carried out by free radical polymerization using ammonium persulfate (APS) and N,N,N′,N′‐tetramethyl ethylenediamine (TEMED) as a redox initiator. The copolymers obtained were then quaternized with 1‐iodooctane. The monomers were characterized by FTIR and 1H NMR spectral studies. The molecular weights and polydispersity values of the monomers were determined with gel permeation chromatography. Quaternized copolymers containing more than 20% amine methacrylate monomer showed microporosity in the range of 9.9–10.4 μm. The antibacterial activity of the quaternized copolymers against Escherichia coli and Staphylococcus aureus was studied using UV–vis spectrophotometer and scanning electron microscopy. Quaternized copolymers showed broad‐spectrum contact‐killing antibacterial properties without releasing any active agent as checked by iodide selective ion meter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

19.
Side‐chain liquid‐crystalline copolymethacrylates (PMm's), containing para‐nitro azobenzene as the mesogenic group and 2‐hydroxylethyl methacrylate (HEMA) as a comonomer, were synthesized by radical polymerization, and their corresponding liquid‐crystalline elastomers (LCEm's) were prepared through chemical crosslinking. All of the polymers (PMm's) and the elastomers studied showed enantiotropic smectic A phases; the clearing temperature (Ti) of the PMm polymers decreased with increasing amount of HEMA, and the Ti of the corresponding LCEm's decreased compared to that of their precursors. Small‐angle X‐ray scattering studies on the copolymers quenched from their liquid‐crystalline phases indicated that the characteristic distance increased with increasing amorphous component content and thus, the amorphous components were in between the smectic layers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2275–2279, 2003  相似文献   

20.
A facile approach is offered to synthesize well‐defined amphiphilic ABC triblock copolymers composed of poly(ethylene glycol) monomethyl ether (MPEO) as A block, poly(L ‐lysine) (PLLys) as B block, and poly(ε‐caprolactone) (PCL) as C block by a combination of ring‐opening polymerization (ROP) and click reactions. The propargyl‐terminated poly(Z‐L ‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) diblock copolymers were synthesized via the ring‐opening polymerization of Nε‐carbobenzoxy‐L ‐lysine N‐carboxyanhydride (Z‐L ‐Lys NCA) in DMF at room temperature using propargyl amine as an initiator and the resulting amino‐terminated poly(Z‐L ‐lysine) then used in situ as a macroinitiator for the polymerization of ε‐caprolactone in the presence of stannous octoate as a catalyst. The triblock copolymers poly(ethylene glycol) monomethyl ether –block‐poly(Z‐L ‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) were synthesized via the click reaction of the propargyl‐terminated PzLLys‐PCL and azido‐terminated poly(ethylene glycol) monomethyl ether (PEO‐N3) in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. After the removal of Z groups of L ‐lysine units, amphiphilic and biocompatible ABC triblock copolymers MPEO‐PLLys‐PCL were obtained. The structural characteristics of these ABC triblock copolymers and corresponding precursors were characterized by NMR, IR, and GPC. These results showed the click reaction was highly effective. Therefore, a facile approach is offered to synthesize amphiphilic and biocompatible ABC triblock copolymers consisting of polyether, polypeptide and polyester. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

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