Synthesis, characterization, and antibacterial activity of metal nanoparticles embedded into amphiphilic comb-type graft copolymers

The synthesis, spectroscopic characterization, and antimicrobial efficiency of gold and silver nanoparticles embedded in novel amphiphilic comb-type graft copolymers having good film-forming properties have been described. Amphiphilic comb-type graft copolymers were synthesized by the reaction of chlorinated polypropylene (PP) (M _w = 140,000 Da) with polyethylene glycol (PEG) (M _n  = 2,000 Da) at different molar ratios. Metal nanoparticles embedded graft copolymers were prepared by reducing solutions of the salts of silver or gold and the copolymer in tetrahydrofuran. The optical properties of the metal nanoparticle embedded copolymers were determined by using UV–visible spectroscopy. Surface plasmon resonance (SPR) of the gold and silver nanoparticle embedded copolymers in toluene was observed at a maximum wavelength (λ_max) of 428 and 551 nm in the UV–VIS absorption spectra, respectively. The average particle diameters of the gold and silver nanoparticles were found to be 50 nm from the high resolution scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Amphiphilic polymer films containing silver and gold nanoparticles were found to be highly antimicrobial by virtue of their antiseptic properties to Escherichia coli and Staphylococcus aureus.     

Synthesis, characterization and micelle formation of amphiphilic graft copolymers

The macromonomer method is a useful tool for the preparation of various graft copolymers with well-defined structure and composition. Macromonomers were prepared by anionic polymerization of styrene followed by a direct coupling reaction of polystyryllithium with an excess of vinylbenzyl chloride. The control of the terminal functional groups is particularly important to ensure the reactivity of macromonomers in the radical copolymerization; the degree of functionality was determined by both n.m.r. and u.v.-vis. spectroscopy to be from 85–99%. Graft copolymers were synthesized by radical copolymerization of (vinylbenzyl) polystyrene macromonomer with 2-hydroxyethyl methacrylate (HEMA), or with acrylic acid. The organization ability of the copolymers to form micelles was investigated by ¹H n.m.r. spectroscopy, and verified by their ability to stabilize emulsions. These copolymers were found to be effective surfactants for emulsion polymerization of polystyrene latexes. © 1997 Elsevier Science Ltd.     

Synthesis and characterization of amphiphilic graft copolymers with poly(ethylene glycol) and cholesterol side chains

Amphiphilic graft copolymers comprising monomeric units of methoxy poly(ethylene glycol) (mPEG)-acrylate, 2-hydroxyethyl methacrylate (HEMA)–cholesterol conjugates and HEMA were synthesized and their properties characterized. The value of the critical micelle concentration (CMC) for these copolymers is linearly proportional to the ratio of the number of mPEG–acrylates to that of the HEMA–cholesterol conjugates per macromolecule (N_PEG/N_c), which is the most important parameter which influences the formation of polymeric micelles. The latter show excellent colloidal stability and their sizes decrease with increasing CMC. Based on the quenching of pyrene fluorescence, the relatively high levels of the loading capacity of pyrene are attributed to the elevated hydrophobicity of the micelle core. The loading capacity of pyrene decreases with increasing CMC. The weight-average partition coefficient for pyrene in polymeric micelles increases with increasing polymer concentration because more micelles are available for accommodating pyrene. Copyright © 2004 Society of Chemical Industry     

Synthesis and aqueous solution characterization of amphiphilic diblock copolymers containing carbazole

A series of near-monodisperse diblock copolymers of 2-(N-carbazolyl)ethyl methacrylate and 2-(dimethylamino)ethyl methacrylate (DMAEMA) of relatively low molecular weights (2600-24,000 g mol⁻¹) were synthesized by group transfer polymerization using tetrahydrofuran (THF) as a solvent. The molecular weight distributions and compositions of all the copolymers were obtained using gel permeation chromatography (GPC) in THF and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Differential scanning calorimetry and thermal gravimetric analysis provided low glass transition temperatures (T_gs) of about 60 °C and decomposition temperatures between 320 and 450 °C for the copolymers, respectively. The three copolymers with the highest DMAEMA content were water-soluble below pH 7. Aqueous GPC at pH 3 showed that the water-soluble block copolymers formed micelles with apparent number average molecular weights above 100,000 g mol⁻¹.     

含聚氧乙烯链段的两亲性接枝共聚物的合成及应用

介绍了含聚氧乙烯链段的两亲性接枝共聚物的制备方法与应用近况。     

含5-氟尿嘧啶的氨基甲酸聚乙二醇酯前药的合成与表征

采用异氰酸-α-氯乙酰酯与不同相对分子质量的聚乙二醇反应得到双氯乙酰氨基甲酸聚乙二醇酯,由于端基的α-氯具有良好的反应活性,将它与抗肿瘤药物5-氟尿嘧啶结合制备不同相对分子质量的高分子前药。对产物进行红外、核磁、紫外表征,证明5-氟尿嘧啶已经成功接到聚乙二醇链的末端,由紫外分光光度法测得最大载药量为22.6%。与5-氟尿嘧啶相比,前药的水溶性得到增强,而且具有长效缓释的功能。前药在不同pH的缓冲液中可以释放5-氟尿嘧啶或其衍生物,当聚乙二醇相对分子质量为2000时水解速度最快,20h的最大释药率为71.5%。     

Synthesis and characterization of amphiphilic polyisobutylene/poly(ethylene glycol) di- and triblock copolymers

Summary Di- and triblock copolymers of polyisobutylene PIB and poly(ethylene glycol) PEG have been prepared and characterized. The syntheses involved the capping with tolylene 2,4-diisocyanate TDI various molecular weight -phenyl--(p-phenol) polyisobutylenes C₆H₅-PIB-C₆H₄OH and ,-di-(p-phenol)polyisobutylenes HOC₆H₄-PIB-C₆H₄OH, or commercially available mono- and di-hydroxyl-terminated PEGs. In this manner a series of PIB-b-PEG diblock copolymers, and PEG-b-PIB-b-PEG and PIB-b-PEG-b-PIB triblock copolymers have been obtained. The complete removal of the prepolymers from these amphiphilic sequential copolymers by conventional solvent extraction techniques could not be achieved because of the very high emulsifying action of the latters. In contrast, satisfactory separation was obtained by column chromatography using mixed (polar/nonpolar) eluents. The blocking efficiencies and composition of the block copolymers have been determined.Part XL V of the Series on New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers).     

两亲性接枝共聚物PVA-g-PBA的合成与表征

以过硫酸钾 (KPS)为引发剂 ,将丙烯酸丁酯 (BA)接枝到聚乙烯醇 (PVA)上 ,制得两亲性接枝共聚物 PVA-g-PBA。用红外光谱、X射线衍射表征了接枝物 ,研究了引发剂浓度、单体浓度及反应时间对单体转化率、接枝率和接枝效率和接枝率对共聚物吸水性能的影响。结果表明在水介质中 ,氮气保护下 ,70℃时 ,以过硫酸钾 (KPS)为引发剂 ,将丙烯酸丁酯 (BA)接枝到聚乙烯醇 (PVA)上 ,[PVA]为 2 .5× 1 0 -4mol/ L,[BA]为 0 .63 mol/ L、[KPS]为 5 .5 5× 1 0 -4时 ,反应 5 h,能获得较高 CM、G和 Ge的接枝物。接枝物的接枝率越高 ,吸水率越低 ,吸水 1 0 h达平衡 ,最大平衡吸水率为 1 88.8%。     

Synthesis and characterization of silicon-containing graft copolymers

Poly(4-t-butoxycarbonyloxystyrene)-g-poly(dimethylsiloxane) and poly(t-butylmethacrylate)-g-poly(dimethylsiloxane) with various chemical compositions were synthesized via free radical polymerization of 4-t-butoxycarbonyloxystyrene (TBCS) or t-butylmethacrylate (TBMA) with silicone macromers. These macromers were prepared by anionic ring-opening polymerization of hexamethylcyclotrisiloxane (D₃) and subsequent termination with a chlorosilane compound having a methacrylate functionality. The morphology of the graft copolymer systems was investigated by DSC and TEM.     

Synthesis and characterization of novel graft copolymers by radiation‐induced grafting

The radiation‐induced graft copolymerization of N‐vinyl‐2‐pyrrolidone (NVP), 4‐vinyl pyridine (4VP), and 2‐vinyl pyridine (2VP) monomers onto poly (ethylene‐alt‐tetrafluoroethylene) (ETFE) was investigated. The influence of synthesis conditions particularly the solvent was studied. Various solvents, such as n‐propanol, isoproponol, benzyl alcohol, methanol, ethanol, cyclohexanone, tetrahydrofuran (THF), nitromethane, 1,4‐dioxane, and n‐heptane were examined for this purpose. Graft copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), and scanning electron microscopy‐energy dispersive spectroscopy (SEM‐EDAX). It was found that the nature of the solvent had profound influence over the grafting reaction. Cyclohexanone, n‐propanol, and isoproponol for 4VP/ETFE grafting, THF and 1,4‐dioxane for NVP/ETFE grafting, and benzyl alcohol and methanol for 2VP/ETFE grafting were found to be the suitable solvents yielding highest graft levels. Isoproponol and n‐propanol are promising in terms of both graft level and mechanical properties for 4VP/ETFE. Grafting of NVP, 4VP, and 2VP onto ETFE were verified through FTIR spectroscopy. Storage modulus and glass transition temperature of the copolymers were found to increase as graft level increased. Surface profile of representative films was also investigated by viewing the distribution of elemental nitrogen using SEM‐EDAX. Results indicated that copolymers of 4VP, NVP, and 2VP are considerably different from each other. 4VP‐based copolymers exhibited relatively more homogenous grafting over the surface compared with NVP‐ and 2VP‐based copolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of anionic graft copolymers containing poly(ethylene oxide) grafts

Graft copolymers containing poly(ethylene oxide) side chain attached to maleic anhydride‐alt‐vinyl methyl ether (MA‐VME) copolymer were prepared by coupling MA‐VME and poly(ethylene glycol) monomethyl ether (MPEG) by esterification in DMF at 90°C. MPEG and dodecyl alcohol (DA) were grafted onto MA‐VME copolymer in o‐xylene at 140°C in the presence of p‐toluene sulfonic acid as catalyst. The molecular weights of MPEG were found to influence the rate of the grafting reaction and the final degree of conversion. The graft copolymers were characterized by IR, GPC, and ¹H‐NMR. DSC was used to examine thermal properties of the graft copolymers. The analysis indicates that grafts have phase‐separated morphology with the backbone and the MPEG grafts forming separate phases. The properties in aqueous solutions of these grafts were studied with respect to aggregation behavior and viscometric properties. In aqueous solution, the polymers exhibited polyelectrolyte behavior (i.e., a dramatic increase of the viscosity upon neutralization). Graft copolymers with DA have lower viscosities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1138–1148, 2002     

Synthesis and characterization of amphiphilic conetworks based on multiblock copolymers

Model amphiphilic conetworks based on cross-linked block copolymers of the hydrophilic ionizable 2-(dimethylamino)ethyl methacrylate (DMAEMA, 25 nominal units per block) and the hydrophobic n-butyl methacrylate (BuMA, 5 nominal units per block) bearing three, five, seven and nine blocks were synthesized using group transfer polymerization. 1,4-Bis(methoxytrimethylsiloxymethylene)cyclohexane and ethylene glycol dimethacrylate were used as the bifunctional initiator and the cross-linker, respectively. Network synthesis was performed by sequential monomer/cross-linker additions to the reaction flask, which was pre-loaded with tetrabutylammonium bibenzoate (polymerization catalyst), tetrahydrofuran (THF, solvent), and initiator. All linear conetwork precursors were characterized using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy and found to have molecular weights (MWs) and compositions reasonably close to the theoretically expected values. All polymer conetworks were characterized in terms of their degree of swelling (DS) in THF, in neutral water, and in aqueous media as a function of the solution pH. It was found that the DSs were highest in acidic pH due to the repulsive forces and the osmotic pressure developed by the ionization of the DMAEMA units. Intermediate values of the DSs were observed in THF, whereas the lowest DSs were measured in neutral water. In THF, the DSs increased with the MWs of the (final) linear (co)polymer precursors, while in acidic water the DSs increased with the DMAEMA content in the (co)networks.     

Synthesis,characterization and properties of amphiphilic butadiene-oxyethylene multiblock copolymers

Butadiene-oxyethylene multiblock copolymers were synthesized via coupling reaction of telechelic α,ω-dihydroxypolybutadiene (PB) and poly(ethylene glycol) with tolylene-2,4-diisocyanate. The poly(oxyethylene) (PEO) content of the purified copolymer was determined by elemental analysis and the structural parameters were calculated from number-average molecular weights of the purified copolymer, determined by membrane osmometry, and those of the prepolymers, determined by vapor pressure osmometry. The total number of blocks varied from 60 to 100. Transmission electron microscopy showed the existence of multiphases in the copolymer. Wide angle X-ray diffraction indicated that the crystallinity increased from 0 to 50% with increasing weight ratio of PEO/PB. These multiblock copolymers exhibit excellent emulsifying properties, as compared to the multiblock copolymers or graft copolymer of oxyethylene and styrene. Only 0.1 g of polymer was needed to make 100 mL of a water/toluene (9:1, w/w) mixture form an emulsion completely. When the weight ratio of water/toluene was changed from 9:1 to 7:3 or the molecular weight of PEG from 6000 to 2000, the oil-in-water type emulsion was changed to water-in-oil type. The copolymers also showed a good phase transfer catalytic effect when applied to the Williamson reaction. Conversion of potassium phenolate into butyl phenolate reached over 95% when the multiblock copolymer containing 3 mmol of PEO was used for 1 g potassium phenolate, whereas no reaction occurred without using the multiblock copolymer at 90°C for 4 h.     

Synthesis, characterization and properties of chitosan modified with poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers

Synthesis of poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers is discussed herein. Siloxane prepolymer was first prepared via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) to form polydimethylsiloxane (PDMS) prepolymers. It was subsequently functionalized with hydroxy functional groups at both terminals. The hydroxy-terminated PDMS can readily react with acid-terminated poly(ethylene glycol) (PEG diacid) to give PEG-PDMS block copolymers without using any solvent. The PEG diacid was prepared from hydroxy-terminated PEG through the ring-opening reaction of succinic anhydride. Their chemical structures and molecular weights were characterized using ¹H NMR, FTIR and GPC, and thermal properties were determined by DSC. The PEG-PDMS copolymer was incorporated into chitosan in order that PDMS provided surface modification and PEG provided good water swelling properties to chitosan. Critical surface energy and swelling behavior of the modified chitosan as a function of the copolymer compositions and contents were investigated.     

聚乙二醇基双氢青蒿素衍生物的合成

通过双氢青蒿素与聚乙二醇反应得到了标题化合物.其结构经红外光谱和氢核磁共振谱确证.     

Synthesis and study of block copolymers based on caprolactam and polyethylene glycol

High-molecular-weight block copolymers of polycaproamide and polyethylene glycol were synthesized and are distinguished by the different size of the polyamide block and number of polyamide and polyethylene oxide blocks in the macromolecule. In the conditions of synthesis of the copolymers used. their molecular characteristics are in good agreement with the calculated characteristics, and the melting point is a linear function of the reciprocal of the average degree of polymerization of the polyamide block in the copolymer. An opinion was advanced concerning the expedient regions of practical use of block copolymers differing in the ratio of stiff (polyamide) and flexible (polyethylene oxide) blocks.Ivanovo State Academy of chemical Engineering. Translated from Khimicheskie Volokna, No. 4, pp. 55–57, July–August, 1996.     

Synthesis and properties of two kinds of amphiphilic graft copolymers with well-defined structure

Polyacrylamide with well-defined polystyrene grafts (PAM-g-PS) and poly(methacrylic acid) with well-defined poly(methyl methacrylate) grafts (PMAA-g-PMMA) were synthesized via macromer techniques. Polymerization conditions and reactivity ratios for the copolymerizations were studied. The graft copolymers were purified by extractions and characterized with IR spectra. Structural parameters of PMAA-g-PMMA were determined by measurement of number average molecular weight of both macromers and copolymers. Both kinds of the graft copolymers are amphiphilic, exhibiting good emulsifying properties. When PAM-g-PS was mixed with PMAA-g-PMMA in a molar ratio of PAM/PMAA = 1, an intermolecular complex membrane was formed. This behaves as a chemical valve; its permeability can be controlled reversibly by changing the pH value. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of aPP/aPS graft copolymers

Summary Graft copolymers of atactic polypropylene (aPP) and polystyrene (PS) were synthesized and characterized by ¹³C NMR analysis. The ¹³C NMR spectra of the grafts exhibited changes with respect to physical blends of identical compositions. The most important occurred in the meso sequences of the aPP blocks of the copolymer. These changes suggest that some grafting took place during the synthesis. SEM micrographs indicate greater interfacial interaction between phases in the copolymers than in the physical blends. Thermal Analysis showed that the Tg of the copolymers is higher than that of the PS homopolymers prepared under the same conditions. This could be the result of an apparent increased in molecular weight caused by the grafting of the aPS into the aPP chains. TGA results indicated that the thermal stability of the copolymer decreases as the aPP content in the copolymer increases.     

新戊二醇改性PET的合成与表征

以对苯二甲酸为主要原料，通过加入2%～15%（摩尔）新戊二醇，合成了一系列不同二醇配比的共聚酯，用示差扫描量热方法研究了该体系的热性能。结果表明，共聚酯的熔点和结晶度均随新戊二醇的加入而降低。