首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Two new kinds of amphiphilic copolymers were synthesized in this work. Poly(1‐octene‐co‐acrylic acid) copolymers were prepared through the copolymerization of 1‐octene and tert‐butyl acrylate, and the hydrolysis of tert‐butyl acrylate units. Poly(1‐octene‐co‐acrylic acid)‐g‐poly (ethylene glycol) copolymers were obtained from the esterification reaction between poly(1‐octene‐co‐acrylic acid) and poly(ethylene glycol) monomethyl ether. They were characterized by means of 1H‐NMR, 13C‐NMR, GPC, and FTIR. These amphiphilic copolymers can form stable micelles in aqueous solutions. The critical micelle concentration was determined by fluorescence spectroscopy. The micellar morphology and size distribution were investigated by transmission electron microscopy and dynamic light scattering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

2.
Novel amphiphilic biodegradable graft copolymer based on poly(aspartic acid) was prepared by attaching monomethoxy polyethylene glycol (mPEG) as hydrophiphic segment to poly(aspartic acid‐g‐octadecylamine) (PASP‐g‐ODA) as hydrophobic backbone. The chemical structures of amphiphilic copolymers were confirmed by FTIR and 1H NMR spectroscopy. The polymeric micelles were prepared with solvent evaporation and their physicochemical properties in aqueous media were characterized by dynamic light scattering (DLS) and fluorescence spectroscopy. These micelles were confirmed to be pH‐sensitive by measuring optical transmittance of micelle solution and the size of micellar aggregates. The number average diameter of polymeric micelles prepared in medium at pH 2.5 was larger than that in neutral and basic medium and showed a bimodal size distribution because of the protonation of carboxyl groups in backbone. Furthermore, the polymeric micelle can load water‐insoluble drug (podophyllotoxin), and the drug release from micelles showed a pH‐dependency. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006  相似文献   

3.
Preparation of amphiphilic graft copolymers of chitosan-g-methacrylate-terminated poly(lactic acid) (CS-g-MPLAn) with various chain length of lactic acid monomers in the copolymers (n = 20, 40, and 70) has been successfully carried out by “grafting on” free radical polymerization. Beside to offer a tunable and easy preparation of chitosan (CS)-based amphiphilic copolymers, the specific purpose is to study the effects of poly(lactic acid) chain length on the micelle properties of the copolymers in water. First, oligomer CS was synthesized by partial oxidation. Second, the methacrylate-terminated poly(lactic acid) with different chain length were synthesized by ring opening polymerization of lactide monomer using 2-hydroxyethyl methacrylate and Sn(Oct)2 as initiator and catalyst, respectively. Finally, the grafting process was carried out by free radical copolymerization using cerium(IV) sulfate as initiator at 70°C for 24 h. The CS-g-MPLAn amphiphilic copolymers were characterized by Fourier transform infrared and proton nuclear magnetic resonance. The hydrophobic drug nanomicelles in water with a narrow-size distribution, positively charged and high stability have been confirmed. The micelle size is significantly bigger on longer chain of poly(lactic acid); however, the stability, loading capacity, and encapsulation efficiency are independent on the chain length. The high-loading capacity and encapsulation efficiency for hydrophobic drug protoporphyrin IX as the model are ensuring the hydrophobic drugs efficacy in photodynamic therapy applications.  相似文献   

4.
Biodegradable amphiphilic copolymers were successfully synthesized by the conjugation of various densities of hydrophobic biocompatible cholesterol (Chol) moieties onto poly(2‐hydroxyethyl aspartamide) and poly(N‐isopropylaminoethyl‐co‐2‐hydroxyethyl aspartamide). These were obtained from polysuccinimde, the thermal polycondensation product of L‐aspartic acid, via a ring‐opening reaction with multifunctional pendant groups, including ethanolamine and N‐isopropylethylenediamine (NIPEDA). Copolymers containing 5–30 mol % Chol showed self‐aggregation behavior in aqueous solution, as evidenced by the dynamic light scattering measurement of their particle size distribution. The average particle size of these copolymers increased linearly with increasing Chol content. Moreover, the presence of secondary amine groups in the poly(2‐hydroxyethyl aspartamide)–NIPEDA system made the conjugation more efficient; however, these also seemed to accelerate the degradation of the copolymers in an aqueous medium. The degradation behavior and pH dependence of the particle size of these copolymers in aqueous solution were also examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

5.
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   

6.
The self-assembly of amphiphilic block-copolymers is a convenient way to obtain soft nanomaterials of different morphology and scale. In turn, the use of a biomimetic approach makes it possible to synthesize polymers with fragments similar to natural macromolecules but more resistant to biodegradation. In this study, we synthesized the novel bio-inspired amphiphilic block-copolymers consisting of poly(N-methacrylamido-d-glucose) or poly(N-vinyl succinamic acid) as a hydrophilic fragment and poly(O-cholesteryl methacrylate) as a hydrophobic fragment. Block-copolymers were synthesized by radical addition–fragmentation chain-transfer (RAFT) polymerization using dithiobenzoate or trithiocarbonate chain-transfer agent depending on the first monomer, further forming the hydrophilic block. Both homopolymers and copolymers were characterized by 1H NMR and Fourier transform infrared spectroscopy, as well as thermogravimetric analysis. The obtained copolymers had low dispersity (1.05–1.37) and molecular weights in the range of ~13,000–32,000. The amphiphilic copolymers demonstrated enhanced thermal stability in comparison with hydrophilic precursors. According to dynamic light scattering and nanoparticle tracking analysis, the obtained amphiphilic copolymers were able to self-assemble in aqueous media into nanoparticles with a hydrodynamic diameter of approximately 200 nm. An investigation of nanoparticles by transmission electron microscopy revealed their spherical shape. The obtained nanoparticles did not demonstrate cytotoxicity against human embryonic kidney (HEK293) and bronchial epithelial (BEAS-2B) cells, and they were characterized by a low uptake by macrophages in vitro. Paclitaxel loaded into the developed polymer nanoparticles retained biological activity against lung adenocarcinoma epithelial cells (A549).  相似文献   

7.
2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene was synthesized by Michael addition reaction using 2,7-dibromofluorene and perfluorohexyl ethyl acrylate as the reactants. 9,9-Bis(perfluorohexylethyl propionate) fluorene copolymers were then synthesized by Suzuki coupling reaction with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborane-diyl)-9,9 -dioctyl fluorene, 2,7-dibromo-9,9-dioctyl fluorene and 2,7-dibromo-9,9-bis(perfluorohexylethyl propionate) fluorene as the monomers. The fluorinated fluorene copolymers were characterized and investigated via Fourier infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectroscopy (1HNMR), ultraviolet absorption spectroscopy (UV–vis), cyclic voltammetry (CV) and photoluminance spectroscopy (PL). Because of the long fluorine-containing alkyl side chain, the ultraviolet absorption peak of 9,9-bis(perfluorohexylethyl propionate) fluorene is blue-shifted compared with poly(9,9-dioctylfluorene)(PF8). The LUMO energy level increases and the energy band gap of copolymers widens. Due to the self-assembly of the long fluoroalkyl side chain, the photoluminance spectra of 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers exhibit a new excimer emission peak at 550 nm. The photoluminance stabilities of the copolymers under irradiation and humid conditions are significantly improved due to protective effect from the long fluoroalkyl side chain. After being irradiated under 500 W iodine tungsten lamp or kept under 70% relative humid conditions, the 9,9-bis(perfluorohexylethyl propionate) fluorene copolymers showed much better photoluminance stability than that of poly(9,9-dioctylfluorene) (PF8). These show that introducing long fluoroalkyl side chain into conjugated polymer main chain is a promising strategy to improve environmental stability of devices based on organic conjugated polymers.  相似文献   

8.
Dan Peng 《Polymer》2007,48(18):5250-5258
A series of well-defined amphiphilic graft copolymers containing hydrophilic poly(acrylic acid) backbones and hydrophobic poly(methyl methacrylate) side chains were synthesized by successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl acrylate) backbone. Grafting-from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distributions. Hydrophobic side chains were connected with the backbone through stable C-C bonds instead of ester connections. The backbone can be easily hydrolyzed to poly(acrylic acid) with HCl without affecting the hydrophobic side chains. The amphiphilic graft copolymers can form stable micelles in water. The critical micelle concentration was determined by fluorescence spectroscopy. The micellar morphologies were found to be vesicles by transmission electron microscopy and changed to spheres with the addition of NaCl.  相似文献   

9.
The copolymers poly(propylene-co-ethylene) (PP/E) and poly(ethylene-co-vinyl acetate) (EVA) and blends of these were modified to develop an artificial matrix which promotes the growth of endothelial cells. Covalent immobilization of amino acids or sequences of adhesion glycoproteins should trigger the formation of an endothelial cell monolayer onto the polymeric surface. Reactive functional groups were generated by saponifying the ester groups of the EVA component. Esterification with oxalylic or malonic dichlorides in the gas phase yielded the required monoesters and gave the best results for further immobilization of amino acids, while reaction with α,ω-dicarboxylic acid dichlorides in solution led to diester formation. Subsequently, various protected amino acids were immobilized via the carbodiimide method. Surface analytical methods like infrared spectroscopy using at tenuated total reflection (IR-ATR), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) were used to prove the modification steps. The analytical results confirmed covalent side-chain generation in the upper surface region. © 1995 John Wiley & Sons, Inc.  相似文献   

10.
Copolymers of aniline and ortho/meta-amino benzoic acid were synthesized by chemical polymerization using an inverse emulsion pathway. The copolymers are soluble in organic solvents, and the solubility increases with the amino benzoic acid content in the feed. The reaction conditions were optimized with emphasis on high yield and relatively good conductivity (2.5×10−1 S cm−1). The copolymers were characterized by a number of techniques including UV-vis, FT-IR, FT-Raman, EPR and NMR spectroscopy, thermal analysis, SEM and conductivity. The influence of the carboxylic acid group ring substituent on the copolymers is investigated. The spectral studies reveal that the amino benzoic acid groups restrict the conjugation along the polymer chain. The SEM micrographs of the copolymers reveal regions of amorphous and crystalline domain. Thermal studies indicate a marginally higher thermal stability for poly(aniline-co-m-amino benzoic acid) compared to poly(aniline-co-o-amino benzoic acid).  相似文献   

11.
The aim in this study is to synthesize amphiphilic linear-dendritic-linear block copolymers consisting of a poly ?-caprolactone linear block, poly(amino-ester) dendritic block and m-PEG linear block. G1, G2 and G3 dendrons were produced by sequential acrylation and Micheal addition reactions, using required amounts of acryloyl chloride and diethanolamine respectively to achieve quantitative growth. Amphiphilic dendrons were synthesized from the reaction of hydroxyl group of G1, G2 and G3 with mPEG-adipoyl chloride and their structures were characterized by FT-IR and 1H NMR spectroscopy. The amphiphilic dendrons can self-assemble and form micelles in water. Their critical micelle concentration (CMC), particle size and zeta potential were determined by fluorescence spectroscopy and dynamic light scattering, respectively. Convergent dendrimers were prepared by self-assembly of the dendrons around oleic acid-stabilized Fe3O4 nanoparticles via the ligand exchange method and their morphologies were characterized by transmission electron microscopy (TEM). The in-vitro release behavior of quercetin from dendrimers and hydrolytic degradation of them were investigated at two pHs (7.4 and 5.8).  相似文献   

12.
Dan Peng 《Polymer》2006,47(17):6072-6080
A series of well-defined amphiphilic graft copolymers consisting hydrophilic poly(acrylic acid) backbones and hydrophobic polystyrene side chains were synthesized by successive atom transfer radical polymerization (ATRP) followed by hydrolysis of poly(methoxymethyl acrylate) (PMOMA) backbone. Grafting-from strategy was employed for the synthesis of graft copolymers with narrow molecular weight distribution. Hydrophobic side chains were connected to the backbone through stable C-C bonds. The backbone can be easily hydrolyzed with HCl without affecting hydrophobic side chains. This family of amphiphilic graft copolymers can form stable micelles in water. The critical micelle concentration was determined by fluorescence spectroscopy. The micellar morphologies and sizes were studied using transmission electron microscopy (TEM) and dynamic light scattering (DLS). The sizes of micelles were dependent on ionic strength, pH value and preparation conditions.  相似文献   

13.
Biodegradable star-shaped poly(?-caprolactone) (PCL) with four arms were synthesized by ring-opening polymerization (ROP) from a symmetric pentaerythritol core via the ‘‘core-first’’ strategy. Subsequently, two samples of the amphiphilic A4B8 star-block copolymers with symmetrical topologies [4s(PCL-b-2sPEG)] were synthesized by a macromolecular coupling reaction between carboxyl-terminated poly(ethylene glycol) (PEG) and 4-arm star-shaped PCL macromers with eight -OH end groups. The latter was prepared by attaching 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid (HHMPA) to 4sPCL using a simple two-step reaction sequence. The in vitro cytotoxicity test indicated no apparent cytotoxicity. The amphiphilic star-block copolymers are capable of self-assembling into spherical micelles in water at room temperature, and they possess low critical micelle concentrations (CMCs) of 2∼8 mg/L in aqueous solution which was determined by fluorescence spectroscopy using pyrene as a probe. Transmission electron microscopy (TEM) measurement demonstrated that the micelles exhibit a spherical shape with a size range of 30∼50 nm in diameter. In addition, the hydrophobic and anticancer drug, quercetin, is loaded effectively in the polymeric micelles, suggesting that these new materials are appropriate candidates as hydrophobic drug nanocarriers.  相似文献   

14.
Four poly(amido-amine)s based on piperazine have been synthesized by poly(acylation-addition) reaction of piperazind with various activated derivatives of acrylic acid. In these polymers, amido-, and amino groups are randomly arranged along the macromolecular chain. These polymers have been fully characterized by hydrolytic analysis, 13C n.m.r., and potentiometric techniques.  相似文献   

15.
A series of well-defined amphiphilic graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic polystyrene side chains were synthesized by hydrolysis of poly(methyl acrylate)-g-polystyrene under basic condition. The backbone and the side chains were synthesized by atom transfer radical polymerization (ATRP), so the molecular weight could be tuned by the variation of the feed ratio or monomer conversion, and the molecular weight distributions of amphiphilic graft copolymers were kept low (PDI < 1.35). The products were characterized by FT-IR, 1H NMR, 13C NMR, and gel permeation chromatography (GPC). The study of self-assembly behavior can benefit the formation of the well-defined structures of the products.  相似文献   

16.
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   

17.
Well‐defined asymmetric amphiphilic ABA′ block copolymers composed of poly(ethylene oxide) monomethylene ether (MPEO) with different molecular weights as A or A′ block and poly(styrene) (PS) as B block were synthesized by the combination of atom transfer radical polymerization (ATRP) and click reactions. First, bromine‐terminated diblock copolymer poly(ethylene oxide) monomethylene ether‐block‐poly(styrene) (MPEO‐PS‐Br) was prepared by ATRP of styrene initiated with macroinitiator MPEO‐Br, which was prepared from the esterification of MPEO and 2‐bromoisobutyryl bromide. Then, the azido‐terminated diblock copolymers MPEO‐PS‐N3 were prepared through the bromine substitution reaction with sodium azide. Propargyl‐terminated MPEO with a different molecular weight was prepared under the basic condition from propargyl alcohol and p‐toluenesulfonyl‐terminated MPEO, which was prepared through the esterification of MPEO and p‐toluenesulfochloride using pyridine as solvent. Asymmetric amphiphilic ABA′ block copolymers, with a wide range of number–average molecular weights from 1.92 × 104 to 2.47 × 104 and a narrow polydispersity from 1.03 to 1.05, were synthesized via a click reaction of the azido‐terminated diblock copolymers and the propargyl‐terminated MPEO in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. The structures of these ABA′ block copolymers and corresponding precursors were characterized by NMR, IR, and GPC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

18.
Modified poly(aspartic acid)s containing pendant allyl groups were synthesized by the reaction of poly(succinimide) with an allyl amine in dimethylformamide. The contents of the allyl groups in the poly(aspartic acid) ranged from 2 to 17.4% confirmed by 1H NMR. Hydrogels were prepared using modified poly(aspartic acid) by chemical crosslinking using redox radical initiators including ammonium persulfate and potassium peroxodisulfate. The morphologies of the poly(aspartic acid)-based hydrogels were investigated by scanning electron microscopy (SEM). The water-absorbent experiments were carried out, and revealed that lightly cross-linked hydrogels resulted in effective water-absorbent properties. These results suggested that allyl group-modified poly(aspartic acid)s are useful in providing biodegradable hydrogels.  相似文献   

19.
Dong Yang  Yongjun Li  Sen Zhang 《Polymer》2010,51(8):1752-1760
A series of well-defined binary hydrophilic-fluorophilic diblock copolymers were synthesized by successive atom transfer radical polymerization (ATRP) of methoxylmethyl acrylate (MOMA) and 4-(4′-p-tolyloxyperfluorocyclobutoxy)benzyl methacrylate (TPFCBBMA) followed by the acidic selective hydrolysis of the hydrophobic poly(methoxymethyl acrylate) (PMOMA) segment into the hydrophilic poly(acrylic acid) (PAA) segment. ATRP of MOMA was initiated by 2-MBP at 50 °C in bulk to give two different PMOMA homopolymers with narrow molecular weight distributions (Mw/Mn ≤ 1.15). PMOMA-b-PTPFCBBMA well-defined diblock copolymers were synthesized by ATRP of TPFCBBMA at 90 °C in anisole using Br-end-functionalized PMOMA homopolymer as macroinitiator and CuBr/PMDETA as catalytic system. The final PAA-b-PTPFCBBMA amphiphilic diblock copolymers were obtained via the selective hydrolysis of PMOMA block in dilute HCl without affecting PTPFCBBMA block. The critical micelle concentrations (cmc) of PAA-b-PTPFCBBMA amphiphilic copolymers in aqueous media were determined by fluorescence spectroscopy using pyrene as probe and these diblock copolymers showed different micellar morphologies with the changing of the composition.  相似文献   

20.
Well-defined amphiphilic block copolymers composed of S-vinyl sulfides and N-isopropyl acrylamide (NIPAM) were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Thermoresponsive core–shell nanoparticles with cross-linked π-conjugate cores were obtained by in situ cross-linking reactions between 4-bromophenyl moieties in the block copolymers and diboronic acids or a diamine compound in the presence of a palladium catalyst following micelle formation in ethanol/H2O or ethanol. We initially investigated RAFT polymerization of two S-vinyl sulfide derivatives, namely phenyl vinyl sulfide (PVS) and 4-bromophenyl vinyl sulfide (BPVS), using a dithiocarbamate-type chain transfer agent (CTA). Then, RAFT polymerization of NIPAM using poly(S-vinyl sulfide) macro-CTAs was conducted to synthesize the amphiphilic block copolymers. Suzuki and Buchwald-Hartwig coupling reactions were found to be effective in the preparation of core–shell nanoparticles with thermoresponsive shells and cross-linked optoelectronic cores. The resulting nanoparticles showed characteristic thermoresponsive properties, as confirmed by turbidity and dynamic light scattering measurements. Stable and uniform core cross-linked nanoparticles were successfully prepared by the in situ palladium-catalyzed coupling reactions, and the optoelectronic and thermoresponsive properties of the nanoparticles could be tuned depending on the nature of the difunctional coupling agents, reaction conditions, and comonomer composition of the block copolymers.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号