共查询到20条相似文献,搜索用时 31 毫秒
1.
Jinyu Huang 《Polymer》2005,46(25):11698-11706
The ATRP copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) with n-butyl acrylate (nBA) was studied by using ethyl 2-bromoisobutyrate (EBriBu) and N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/Cu(I)Br as the initiator and catalyst, respectively. The reactivity ratios of the monomers in the copolymerization were determined using the Kelen-Tüdõs method and were found to be rBMDO=0.08 and rnBA=3.7. The copolymer yield decreased with higher amounts of BMDO in the initial feed. The structure of these copolymers was thoroughly characterized by 1D and 2D NMR techniques and quantitative ring opening of BMDO in its copolymerization was demonstrated. The hydrolytic degradation behavior of the BMDO/nBA copolymers was also studied. 相似文献
2.
AB amphiphilic comb-like block copolymers of poly(oligo[ethylene glycol] methyl ether methacrylate) and polydimethylsiloxane were synthesised with a methodology based on atom transfer radical polymerization (ATRP). The anionic ring opening polymerisation of hexamethylcyclotrisiloxane followed by reaction with 3-(chlorodimethylsilyl) propyl 2-bromo-2-methylpropanoate propyldimethylchlorosilane gave suitable macroinitiators for the ATRP of oligo[ethylene glycol] methyl ether methacrylate. The latter synthetic procedure was optimised by performing a number of syntheses varying the reaction solvent, catalytic complex and the temperature used. Copolymers with relatively high polydispersity indices (Mw/Mn>1.3) could be synthesised at room temperature by employing a Cu(I)Br:N,N,N′,N′,N″-pentamethyldiethylenetriamine complex in n-propanol with Cu(II)Br. The optimum reaction conditions employed a Cu(I)Cl:N-(n-propyl)-2-pyridyl(methanimine) complex with an n-propanol/water mixture or toluene as solvent at 90 °C. This gave block copolymers of the desired molecular weights and polydispersity indices of less than 1.1. The block copolymers were characterised with 1H NMR and 13C NMR spectroscopy and size exclusion chromatography. 相似文献
3.
Dhruba P. Chatterjee 《Polymer》2006,47(6):1812-1819
Controlled polymerization of higher alkyl methacrylates, e.g. lauryl methacrylate (LMA) and stearyl methacrylate (SMA) has been successfully achieved by atom transfer radical polymerization (ATRP) at ambient temperature using CuCl/N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA)/tricaprylylmethylammonium chloride (Aliquat®336) as the catalyst system and ethyl 2-bromoisobutyrate or 2,2,2-trichloroethanol as the initiator. Although the bulk polymerization gives satisfactory control, the latter becomes better when anisole or THF is added into the system. Without AQCl the control was lost. A large deviation of molecular weight from theory has been observed which has been attributed to the very high-molecular weight of the dead polymers formed during the building-up of the persistent radical. The controlled polymers have been used as macroinitiators for block (di, tri and penta) ATR copolymerization with several methacrylates. 相似文献
4.
Atom transfer radical polymerization of lauryl methacrylate (LMA) was carried out in the presence of various ligands using ethyl-2-bromoisobutyrate as initiator and CuBr as catalyst in toluene at 95 °C. The ligands used were 2,2′-bipyridyl,4,4′-dimethyl-2,2′-bipyridyl, N,N,N′,N′,N″-pentamethyldiethylenetriamine (PMDETA) and N-(n-propyl)-2-pyridylmethanimine (PPMI). Controlled polymerization was observed with PMDETA and PPMI ligands and poly(LMA)s with narrow molecular weight distribution (MWD) (Mw/Mn≤1.2) were obtained. The first-order time-conversion plot showed the presence of termination in the presence of PMDETA. A linear first-order time-conversion plot with a small induction period (∼10 min) was observed in the presence of PPMI ligand. Di-block copolymers of LMA and methylmethacrylate with controlled molecular weight and narrow MWDs were synthesized via sequential monomer addition. 相似文献
5.
A supramolecular polymer formed by N,N′,N″-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide (DO3B) in n-decane (C10) possesses large macro-dipoles naturally generated by three-fold inter-molecular hydrogen bonding aligned along its helical columnar structure connected by defective portions, which are DO3B molecules containing failure in the hydrogen bond formation, in the order of head to tail arrangement without dipole inversion like type-A polymers. 相似文献
6.
Homogeneous atom transfer radical polymerization of methyl methacrylate (MMA) under microwave irradiation (MI) with low concentration of initiating system [ethyl 2-bromobutyrate (EBB)/CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)] was successfully carried out in N,N-dimethylformamide (DMF) at 69 °C. Plots of ln ([M]0/[M]) vs. time and molecular weight evolution vs. conversion showed a linear dependence. A 27.3% conversion for a polymer with number-average molecular weight (Mn) of 57,280 and a polydispersity index (PDI) of 1.19, was obtained under MI (360 W) with the ratio of [MMA]0/[EBB]0/[CuCl]0/[PMDETA]0=2400/1/2/2 in only 150 min; but 963 min was needed under conventional heating (CH) process to reach a 26.0 % conversion (Mn=63,990 and PDI=1.14) under identical polymerization conditions, indicating a significant enhancement of the polymerization rate under MI. 相似文献
7.
At room temperature atom transfer radical polymerization (ATRP) of N-vinylpyrrolidone (NVP) was carried out using 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradecane (Me6Cyclam) as ligand in 1,4-dioxane/isopropanol mixture. Methyl 2-chloropropionate (MCP) and copper(I) chloride were used as initiator and catalyst, respectively. The polymerization of NVP via ATRP could be mediated by the addition of CuCl2. The resultant poly(N-vinylpyrrolidone) (PNVP) has high conversion of up to 65% in 3 h, a controlled molecular weight close to the theoretical values and narrow molecular weight distribution between 1.2 and 1.3. The living nature of the ATRP for NVP was confirmed by the experiments of PNVP chain extension. With PNVP-Cl as macroinitiator and N-methacryloyl-N′-(α-naphthyl)thiourea (MANTU) as a hydrophobic monomer, novel fluorescent amphiphilic copolymers poly(N-vinylpyrrolidone)-b-poly(N-methacryloyl-N′-(α-naphthyl)thiourea) (PNVP-b-PMANTU) were synthesized by ATRP. PNVP-b-PMANTU copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The results revealed that PNVP-b-PMANTU presented a blocky architecture. 相似文献
8.
The low efficiency of p-toluenesulfonyl chloride (TsCl) initiator for the polymerization of methyl methacrylate (MMA), when used in conjunction with N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) and CuBr under atom transfer radical polymerization (ATRP) conditions was investigated. A major by-product in the formation of poly(methyl methacrylate) was identified as N,N-dimethyl-p-toluenesulfonamide (5) and accounted for approximately half of the initiator. Compound 5 was shown to form by the direct reaction of PMDETA and TsCl. In a model experiment equimolar amounts of TsCl, PMDETA and CuBr reacted at 80°C in p-xylene resulted in the formation of 5 and two other unsaturated sulfones 2-methyl-3-[(4-methylphenyl)sulfonyl]-2-propenoic acid methyl ester (6) and 2-[[4-methylphenyl)sulfonyl]methyl]-2-propenoic acid methyl ester (7), formed by the dehydrohalogenation and subsequent isomerization of an intermediate chloro-adduct, 1-(4-methylbenzenesulfonyl)-2-chloro-2-(methyl)methyl propionate (2). Molecular modeling predicted the unsaturated sulfone 7 was thermodynamically more stable than the higher conjugated sulfone 6 and this was confirmed by the isomerization of 6 to 7 at room temperature under mild basic conditions. The absence of 6 and 7 in the polymerization of MMA under ATRP conditions showed that in the early stages of polymerization in the presence of excess MMA, the intermediate chloro-adduct 2 is not formed. 相似文献
9.
Two compounds containing the benzothiazole moiety, 4-(2-benzothiazole-2-yl-vinyl)-phenyl methacrylate (BVMA) and 2-bromo-2-methyl-propionic acid 4-(2-benzothiazole-2-yl-vinyl)-phenyl ester (BPBVE) were synthesized. Atom transfer radical polymerization (ATRP) of BVMA was conducted at 60 °C using BPBVE and CuBr/2,2′-bipyridine (BPY) as initiator and catalyst, respectively. Chain extension with 4-methacryloxy-hexyloxy-4′-nitrostilbene (MHNS) was conducted using PBVMA as the macroinitiator. The homopolymer PBVMA in DMF solution emitted blue fluorescence, and the copolymer PBVMA-b-PMHNS emitted orange fluorescence at about 610 nm due to the intramolecular energy transfer. ATRP of BVMA was also conducted using 2-bromo-2-methyl-propionic acid 4-nitrostilbene-hexyloxy ester (BPNHE) as an initiator. The obtained polymer was characterized via 1H NMR and the fluorescence intensity was found to change with increasing number average molecular weight (Mn). The polymer with Mn = 15900 emitted white fluorescence in DMF solution. 相似文献
10.
Hormoz Eslami 《Polymer》2005,46(15):5484-5493
The emulsion atom transfer radical polymerization (ATRP) of 2-ethylhexyl methacrylate (EHMA) was carried out with ethyl 2-bromoisobutyrate (EBiB) as an initiator and copper bromide (CuBr)/4,4′-dinonyl-2,2′-bipyridyl (dNbpy) as a catalyst system. The effects of surfactant type and concentration, temperature, monomer/initiator ratio, and CuBr2 addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the polymerization systems with Tween 80 and Brij 98 as surfactants at 30 °C gave the best latex stability. The polymer samples prepared under these conditions had narrow molecular weight distributions (Mw/Mn=1.1-1.2) and linear relationships of number-average molecular weight versus monomer conversion. 相似文献
11.
The polymerization by ATRP of hydroxy and amino functional acrylates and methacrylates with tert-butyldimethylsilyl (TBDMS) or tert-butyloxycarbonyl (BOC) protective groups has been studied for the first time achieving high control over molecular weight and polydispersity. Detailed investigation of the ATRP of 2-{[tert-butyl(dimethyl)silyl]oxy}ethyl acrylate (M2b) in bulk and 2-[(tert-butoxycarbonyl)amino]ethyl 2-methylacrylate (M3a) in diphenyl ether (DPE) showed that the type of ligand plays an important role on either the polymerization rate or the degree of control of the polymerization. Among the ligands used, N,N,N,′N″N″-pentamethyl diethylenetriamine (PMDETA) was the most suitable ligand for ATRP of all functional acrylates and methacrylates. The kinetics of M2b and M3a polymerization using PMDETA as a ligand was reported and proved the living character of the polymerization. Well-defined block copolymers based on a halogen terminated polystyrene (Pst) macroinitiator and the functional acrylate and methacrylate monomers were successfully synthesized by ATRP, and subsequent deprotection of the protective groups from the acrylate or methacrylate segment afforded amphiphilic block copolymers with a specific solubility behavior. 相似文献
12.
Atom transfer radical polymerization (ATRP) is a promising method to synthesize well‐defined polymer/inorganic nanoparticles. However, the surface‐initiated ATRP from commercially mass produced inorganic nanoparticles has seldom been studied. In this study, the surface‐initiated ATRP of methylmethacrylate (MMA) from commercially mass produced fumed silica (SiO2) nanoparticles was investigated. Unlike the ATRP of MMA initiated from a free initiator, the controllability of ATRP of MMA from the surface of fumed silica nanoparticles was much better using ligand 2,2'‐bipyridine (bpy) than N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA) as the initiator was immobilized on the surface of the SiO2 nanoparticles and the presence of the SiO2 nanoparticles made the CuCl/bpy catalyst system a homogeneous catalyst system and CuCl/PMDETA a heterogeneous one. The appropriate molar ratio of monomer and initiator was essential for preparing controlled PMMA/SiO2 nanoparticles. The entire process of ATRP of MMA from the surface of SiO2 nanoparticles was controllable when using bpy as ligand, xylene as solvent and with a monomer to initiator ratio of 300:1. The 1H NMR results indicated that the PMMA on the surface of the SiO2 was prepared via ATRP initiated from 4‐(chloromethyl)phenyltrimethoxysilane. The well‐defined PMMA/SiO2 nanoparticles obtained have good thermal stability and are well dispersed in organic media as proved by TGA, dynamic light scattering and transmission electron microscopy. © 2013 Society of Chemical Industry 相似文献
13.
MMA (methyl methacrylate) was polymerized in different ATRP systems using the different ligands of HMTETA (1, 1, 4, 7, 10, 10, hexamethyltriethylenetetraamine), TMEDA (N,N,N′,N′-Tetramethylethylenediamine) with copper salts (CuBr/CuBr2) and EBriB was used as an initiator in toluene at a reaction temperature of 80 °C. Both conventional and a low catalyst to initiator ratios ranging from 1/1 to 0.01/1 were compared in this study. All four of the ATRP methods, such as normal, reverse, AGET and ATRP using a high oxidation state metal complex without any additives, were evaluated at different conditions. The ATRP using a high oxidation state metal system in the absence of a conventional radical initiator like AIBN, which is used in reverse ATRP, or reducing agents such as Sn (EH)2 in AGET ATRP was a better controlled system in terms of both the catalytic activity and controllability (PDI ∼ 1.2). 相似文献
14.
Guangyu Liu 《Polymer》2009,50(12):2578-163
The pH-sensitive hollow poly(N,N′-methylenebisacrylamide-co-methacrylic acid) (P(MBAAm-co-MAA)) microspheres with movable magnetic/silica (Fe3O4/SiO2) cores were prepared by the selective removal of poly(methacrylic acid) (PMAA) layer in ethanol/water from the corresponding Fe3O4/SiO2/PMAA/P(MBAAm-co-MAA) tetra-layer microspheres, which were synthesized by the distillation precipitation copolymerization of N,N′-methylenebisacrylamide (MBAAm) and methacrylic acid (MAA) in the presence of Fe3O4/SiO2/PMAA tri-layer microspheres as seeds in acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The Fe3O4/SiO2/PMAA tri-layer microspheres were afforded by the distillation precipitation polymerization of MAA with 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified Fe3O4/SiO2 core-shell particles as the seeds. The functional multi-layer inorganic/polymer microspheres and the corresponding hollow polymer microspheres with movable magnetic cores were characterized with transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectra, dynamic light scattering (DLS), and vibrating sample magnetometer (VSM). 相似文献
15.
A comparative study was conducted on the kinetic of electropolymerization of ortho, meta and N-alkyl and alkoxy substituted anilines in 1.0 M HCl using cyclic voltammetry. The results show that the net rate of polymer formation was strongly dependent upon the steric hindrance, stability of the radical cations, reactivity of the monomers as well as switch potential. Substituents determine the relative importance of the pathways that lead to formation of polymer or soluble products. The results also indicate that the mutual effect of switch potential on the growth of polymer and its degradation is closely related to the electronic effect of substituent groups. A kinetic expression for the autoacceleration process in the electrochemical polymerization of these aniline derivatives is expressed as ν=kn[p]n′[M]+k′n′[M]−k″n″[p] in which k, k′, [M], [p], and k″ are the initiation (nucleation process) rate constant, the rate constant when the polymer is deposited on the electrode, monomer concentration, the total amount of polymer, and the rate constant of degradation process, respectively. 相似文献
16.
A series of well-defined ABA triblock copolymers of poly(methyl acrylate)-polystyrene-poly(methyl acrylate) (PMA-b-PS-b-PMA) with different molecular weights were synthesized using Cl-PS-Cl as macroinitiator, CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) as catalyst system via atom transfer radical polymerization (ATRP). Amphiphilic triblock copolymer poly(potassium acrylate)-polystyrene-poly(potassium acrylate) (PKAA-b-PS-b-PKAA) was obtained by hydrolyzing PMA-b-PS-b-PMA. The self-assembly behavior of the triblock copolymers in organic solutions, which is a good solvent for the PS block and in aqueous solutions, which is a good solvent for the PKAA blocks was studied by high performance particle sizer (HPPS). The results showed that the Z-average size of the micelles obviously increases with increase in molecular weight of triblock copolymers, and the micelles in organic solutions are relatively more stable than in aqueous solutions. The effect of the length of PS block on the Z-average size of the micelles is more obvious in organic solution than in aqueous solution. The morphology of triblock copolymers PKAA-b-PS-b-PKAA in aqueous solution, which is a nearly ‘pearl-necklace’-like shape, was examined by transmission electron microscopy (TEM) at room temperature. 相似文献
17.
The ATRP of methyl methacrylate (MMA) with the system of FeCl2·4H2O, N,N,N′,N″,N″-penta(methyl acylate)diethylenetriamine (MA5-DETA) and ethyl 2-bromoisobutyrate (EBiB) showed high activity and is not well-controlled. The addition of a certain amount of FeCl3·6H2O as the additive into the above system results in the decrease of the polymerization rate and the improvement of the controllability. When SnCl2·2H2O was added instead of FeCl2·4H2O, a novel catalyst system SnCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA formed shows better controllability, higher catalytic activity and higher initiating efficiencies (more than 90%) in comparison with the system FeCl2·2H2O/FeCl3·6H2O/EBiB/MA5-DETA. The polydispersities of the polymers kept range from Mw/Mn=1.18-1.26. The real active species in the new system is Fe (II) formed from the reaction of FeCl3·6H2O with the active radical species produced from the reaction of SnCl2·2H2O with EBiB. 相似文献
18.
The stereospecific atom transfer radical polymerizations of acrylamide were achieved in the presence of the Lewis acid Y(OTf)3 or AlCl3 as stereospecific catalyst using chloroacetic acid/CuCl/N,N,N′,N′-tetramethyl-ethylenediamine (TMEDA) as initiating system. The addition of Lewis acid Y(OTf)3 in the ATRP of acrylamide led to an increased polymerization rate and an improved tacticity of polyacrylamide (m ∼ 71%) at the expense of controllability of the molecular weight distribution. In the case of AlCl3, the polymerizations were committed to afford the resultant polyacrylamide with lower polydispersity index ranging from 1.03 to 1.42 and well-controlled tacticity with meso content ranging from 57 to 76% depending on the different reaction conditions used. Lower temperature or higher concentration of the feeding Lewis acid helped to obtain the polyacrylamide with increased tacticity which revealed a decreased glass transition temperature (Tg). 相似文献
19.
J ChenA.K Burrell G.E CollisD.L Officer G.F SwiegersC.O Too G.G Wallace 《Electrochimica acta》2002,47(17):2715-2724
Novel ferrocene-substituted thiophene and terthiophene compounds, trans-1-(3′-thienyl)-2-(ferrocenyl)ethene and trans-1-((2′,2″:5″,2?-terthiophen)-3″-yl)-2-(ferrocenyl)ethene, have been used to produce homopolymer and copolymer materials. The copolymer of trans-1-(3′-thienyl)-2-(ferrocenyl)ethene with pyrrole and the homopolymer of trans-1-((2′,2″:5″,2?-terthiophen)-3″-yl)-2-(ferrocenyl)ethene were characterised using cyclic voltammetry (CV), UV-visible spectroscopy, scanning electron microscopy (SEM) and four point probe conductivity measurements. Results obtained suggest that the ferrocene moiety plays a catalytic role in the electropolymerisation process. Both the copolymer and homopolymer displayed cyclic voltammograms with redox peaks that can be assigned to the ferrocene moiety and the polymer backbone. The UV-visible spectra and morphology of the copolymer of trans-1-(3′-thienyl)-2-(ferrocenyl)ethene with pyrrole were similar to those of polypyrrole, but the spectra and morphology of the homopolymer of trans-1-((2′,2″:5″,2?-terthiophen)-3″-yl)-2-(ferrocenyl)ethene were different from those of polyterthiophene. The conductivity of the copolymer was determined to be 0.13 S cm−1 whereas that of the homopolymer of trans-1-((2′,2″:5″,2?-terthiophen)-3″-yl)-2-(ferrocenyl)ethene was 82.6 μS cm−1. The copolymer or homopolymer modified Pt disk electrodes facilitated access to the redox centre within Cytochrome C during CV, and their potential use as biosensors has been demonstrated. 相似文献
20.
Hydroxyethylcellulose‐graft‐poly (N, N‐dimethylacrylamide) was synthesized by successive atom transfer radical polymerization (ATRP) of N,N‐dimethylacrylamide (DMA) monomer using HEC‐Br as initiator, CuBr and 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazamacrocyclotetradecane (Me6[14]aneN4) as catalyst and ligand, with molar ratio DMA: HEC‐Br (C? Br): CuBr: Me6[14]aneN4 = 100 : 1 : 1 : 3. HEC–Br macroinitiator was synthesized by esterification of HEC with 2‐bromoisobutyryl bromide. GPC and 1H NMR studies show that the molecular weight of the resulting PDMA increased linearly with the conversion. Within 6 h, the polymerization can reach almost 60% of conversion. The copolymer is applied for the separation of basic proteins in capillary electrophoresis. The results show that this medium has a powerful capability in resisting basic proteins adsorption because the polymer forms noncovalent coating in silica capillaries. With a broad range of pH 2–7, proteins were separated with sufficient efficiencies above 200,000 plates/m. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献