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1.
In this work, methyl methacrylate (MMA) was polymerized by initiator for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) method to obtain low molecular weight living polymers. The ATRP initiator was ethyl 2‐bromoisobutyrate, the catalyst ligand complex system was FeCl3·6H2O/succinic acid, and the conventional radical initiator 2,2′‐azobisisobutyronitrile was used as a thermal radical initiator. Polymers with controlled molecular weight were obtained with ppm level of Fe catalyst complex at 90°C in N,N‐dimethylformamide. The polymer was characterized by nuclear magnetic resonance (NMR). The molecular weight and molecular weight distribution of the obtained poly (methyl methacrylate) were measured by gel permeation chromatography method. The kinetics results indicated that ICAR ATRP of MMA was a “living”/controlled polymerization, corresponding to a linear increase of molecular weights with the increasing of monomer conversion and a relatively narrow polydispersities index. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

2.
Poly(methyl methacrylate)‐poly(L ‐lactic acid)‐poly(methyl methacrylate) tri‐block copolymer was prepared using atom transfer radical polymerization (ATRP). The structure and properties of the copolymer were analyzed using infrared spectroscopy, gel permeation chromatography, nuclear magnetic resonance (1H‐NMR, 13C‐NMR), thermogravimetry, and differential scanning calorimetry. The kinetic plot for the ATRP of methyl methacrylate using poly(L ‐lactic acid) (PLLA) as the initiator shows that the reaction time increases linearly with ln[M]0/[M]. The results indicate that it is possible to achieve grafted chains with well‐defined molecular weights, and block copolymers with narrowed molecular weight distributions. The thermal stability of PLLA is improved by copolymerization. A new wash‐extraction method for removing copper from the ATRP has also exhibits satisfactory results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

3.
A series of PB‐g‐SAN impact modifiers (polybutadiene particles grafted by styrene and acrylonitrile) are synthesized by seed emulsion copolymerization initiated by oil‐soluble initiator, azobisiobutyronitrile (AIBN). The ABS blends are obtained by mixing SAN resin with PB‐g‐SAN impact modifiers. The mechanical behavior and the phase morphology of ABS blends are investigated. The graft degree (GD) and grafting efficiency (GE) are investigated, and the high GD shows that AIBN has a fine initiating ability in emulsion grafting of PB‐g‐SAN impact modifiers. The morphology of the rubber particles is observed by the transmission electron microscopy (TEM). The TEM photograph shows that the PB‐g‐SAN impact modifier initiated by AIBN is more likely to form subinclusion inside the rubber particles. The dynamic mechanical analysis on ABS blends shows that the subinclusion inside the rubber phase strongly influences the Tg, maximum tan δ, and the storage modulus of the rubber phase. The mechanical test indicates that the ABS blends, which have the small and uniform subinclusions dispersed in the rubber particles, have the maximum impact strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007  相似文献   

4.
Dispersion behavior of multiwalled carbon nanotube (MWCNT), rheological and mechanical properties of various MWCNT/poly(styrene‐co‐acrylonitrile) (SAN) nanocomposites were investigated. MWCNT/SAN nanocomposites were prepared by three different methods; MWCNT/SAN melt blending, MWCNT/SAN in situ atom transfer radical polymerization (ATRP) and functionalized‐MWCNT/SAN in situ ATRP. Formation of SAN onto the surface of MWCNT and the molecular weight of grafted‐SAN were confirmed by fourier transform infrared spectra, 1H‐NMR and 13C‐NMR. Crossover frequency of storage and loss modulus from rheological measurement and dynamic mechanical analysis showed that functionalized MWCNT/SAN in situ ATRP nanocomposite showed more uniform dispersion of MWCNT. Improved mechanical and electrical properties were observed for functionalized MWCNT/SAN in situ ATRP nanocomposite. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

5.
Summary Atom transfer radical polymerization with FeCl2/CH3COOH as the catalyst has been successfully implemented for styrene. Various initiators have been used, among which carbon tetrachloride is the most effective one. High molecular weight products were obtained when CCl4 was used as the initiator, and the measured molecular weight was close to the calculated one. Block copolymerization (PS-b-PMMA) was performed to confirm the living/controlled nature of the polymerization. 1H NMR was used to characterize the structure of the macromolecular initiator and the block copolymer. If other initiators, such as benzyl bromide, ethyl 2-bromopropionate and α-bromoethyl benzene, were used, the polymerization occurred at ambient temperature resulting in oligomer. The molecular weight of the oligomer approaches to 4600 (Mn,th= 10000). Thus acetic acid, which is cheaper and less toxicity, can be used as coordinative ligand in ATRP initiated by CCl4 mediated by iron. Received: 13 March 2000/Revised version: 13 November 2000/Accepted: 20 November 2000  相似文献   

6.
In the present investigation, silica nanoparticles have been coated with poly(styrene-co-acrylonitrile) (SAN) copolymer brushes synthesized via surface-initiated atom transfer radical polymerization (ATRP). In the initial step, silica nanoparticles were functionalized with triethoxysilane-based ATR initiator, 6-(2-bromo-2-methyl) propionyloxy hexyl triethoxysilane. Successful formation of the covalent linkages between ATRP initiator and silica nanoparticles is further corroborated using thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The surface initiated ATRP of the styrene and the acrylonitrile mediated by a copper complex was carried out using the initiator fixed silica nanoparticles in the presence of a sacrificial (free) initiator. The polymerization is preceded in a living manner in all examined cases, producing nanoparticles coated with well-defined poly(styrene-co-acrylonitrile) (SAN) brushes with molecular weight in the range of 12–22 kDa. SAN-grafted silica nanoparticles were characterized using TGA which showed significant weight loss in the temperature range of 340–420 °C confirming the formation of the polymer brushes on the surface with graft densities in the range of 0.109–0.190 chains/nm2. Successful formation of the SAN copolymer brushes are further characterized by FTIR and proton nuclear magnetic resonance spectroscopy techniques. Differential scanning calorimetric studies revealed that the SAN copolymer grafted onto silica nanoparticles exhibits higher glass transition temperatures than free SAN copolymers. Transmission electron microscopy and dynamic light scattering studies revealed that the SAN copolymer-grafted silica nanoparticles showed relatively fine dispersion in organic solvents such as tetrahydrofuran, when compared to bare silica nanoparticles.  相似文献   

7.
The atom transfer radical polymerization (ATRP) of n‐docosyl acrylate (DA) was studied at 80°C in N,N‐dimethylformamide using the carbon tetrabromide/FeCl3/2,2′‐bipyridine (bpy) initiator system in the presence of 2,2′‐azobisisobutyronitrile (AIBN) as the source of reducing agent. The rate of polymerization exhibits first‐order kinetics with respect to the monomer. The linear relationship between the molecular weight of the resulting poly(n‐docosyl acrylate) with conversion and the narrow polydispersity of the polymers indicates the living characteristics of the polymerization reaction. The significant effect of AIBN on the ATRP of DA was studied keeping [FeCl3]/[bpy] constant. A probable reaction mechanism for the polymerization system is postulated to explain the observed results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2147–2154, 2005  相似文献   

8.
Free radical solution copolymerization of acrylonitrile (AN) and itaconic acid (IA) was performed with DMSO‐d6 as the solvent and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. Weight ratio of the monomers to solvent and molar ratio of initiator to monomers were constant in all experiments. The initial comonomer composition was the only variable in this study. On‐line 1H NMR spectroscopy was applied to follow individual monomer conversion. Mole fraction of AN and IA in the reaction mixture (f) and in the copolymer chain (F) were measured with progress of the copolymerization reaction. Overall monomer conversion versus time and also compositions of monomer mixture and copolymer as a function of overall monomer conversion were calculated from the data of individual monomer conversion versus time. Total rate constant for the copolymerization reaction was calculated by using the overall monomer conversion versus time data and then kp/kt0.5 was estimated. The dependency of kp/kt0.5 on IA concentration was studied and it was found that this ratio decreases by increasing the mole fraction of IA in the initial feed. The variation of comonomer and copolymer compositions as a function of overall monomer conversion was calculated theoretically by the terminal model equations and compared with the experimental data. Instantaneous copolymer composition curve showed the formation of alternating copolymer chain during copolymerization reaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3253–3260, 2007  相似文献   

9.
The relevance of penultimate monomer unit (PMU) effects and the selection of the correct initiator species under typical reversible deactivation radical copolymerization conditions is illustrated, using matrix‐based kinetic Monte Carlo simulations allowing the visualization of all monomer sequences along individual chains. Initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) is selected as illustrative polymerization technique with n‐butyl acrylate and methyl methacrylate as comonomers, aiming at the synthesis of well‐defined gradient copolymers. Using literature based model parameters, in particular temperature dependent monomer and radical reactivity ratios, it is demonstrated that PMU effects on propagation and ATRP (de)activation cannot be ignored to identify the most suited ICAR ATRP reactants (e.g., tertiary ATRP initiator) and reaction conditions (e.g., feeding rates under fed‐batch conditions). The formulated insights highlight the need for further research on PMU effects on all reaction steps in radical polymerization. © 2017 American Institute of Chemical Engineers AIChE J, 2017  相似文献   

10.
The aim of the study was to investigate the synthesis of a copolymer bearing cyclic carbonate and its miscibility with styrene/acrylonitrile copolymer (SAN) or poly(vinyl chloride) (PVC). (2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether (OVE) as a monomer was synthesized from glycidyl vinyl ether and CO2 using quaternary ammonium chloride salts as catalysts. The highest reaction rate was observed when tetraoctylammonium chloride (TOAC) was used as a catalyst. Even at the atmospheric pressure of CO2, the yield of OVE using TOAC was above 80% after 6 h of reaction at 80°C. The copolymer of OVE and N‐phenylmaleimide (NPM) was prepared by radical copolymerization and was characterized by FTIR and 1H‐NMR spectroscopies and differential scanning calorimetry (DSC). The monomer reactivity ratios were given as r1 (OVE) = 0.53–0.57 and r2 (NPM) = 2.23–2.24 in the copolymerization of OVE and NPM. The films of poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were cast from N‐dimethylformamide. An optical clarity test and DSC analysis showed that poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were both miscible over the whole composition range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1809–1815, 2000  相似文献   

11.
Copolymerization of styrene (St) and methyl methacrylate (MMA) was carried out using 1,1,2,2‐tetraphenyl‐1,2‐bis (trimethylsilyloxy) ethane (TPSE) as initiator; the copolymerization proceeded via a “living” radical mechanism and the polymer molecular weight (Mw) increased with the conversion and polymerization time. The reactivity ratios for TPSE and azobisisobutyronitrile (AIBN) systems calculated by Finemann–Ross method were rSt = 0.216 ± 0.003, rMMA= 0.403 ± 0.01 for the former and rSt= 0.52 ± 0.01, rMMA= 0.46 ± 0.01 for the latter, respectively, and the difference between them and the effect of polymerization conditions on copolymerization are discussed. Thermal analysis proved that the copolymers obtained by TPSE system showed higher sequence regularity than that obtained by the AIBN system, and the sequence regularity increased with the content of styrene in copolymer chain segment. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1474–1482, 2001  相似文献   

12.
The paper describes the synthesis of block copolymers of methyl methacrylate (MMA) and N‐aryl itaconimides using atom‐transfer radical polymerization (ATRP) via a poly(methyl methacrylate)–Cl/CuBr/bipyridine initiating system or a reverse ATRP AIBN/FeCl3·6H2O/PPh3 initiating system. Poly(methyl methacrylate) (PMMA) macroinitiator, ie with a chlorine chain‐end (PMMA‐Cl), having a predetermined molecular weight (Mn = 1.27 × 104 g mol?1) and narrow polydispersity index (PDI = 1.29) was prepared using AIBN/FeCl3·6H2O/PPh3, which was then used to polymerize N‐aryl itaconimides. Increase in molecular weight with little effect on polydispersity was observed on polymerization of N‐aryl itaconimides using the PMMA‐Cl/CuBr/Bpy initiating system. Only oligomeric blocks of N‐aryl itaconimides could be incorporated in the PMMA backbone. High molecular weight copolymer with a narrow PDI (1.43) could be prepared using tosyl chloride (TsCl) as an initiator and CuBr/bipyridine as catalyst when a mixture of MMA and N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 was used. Thermal characterization was performed using differential scanning calorimetry (DSC) and dynamic thermogravimetry. DSC traces of the block copolymers showed two shifts in base‐line in some of the block copolymers; the first transition corresponds to the glass transition temperature of PMMA and second transition corresponds to the glass transition temperature of poly(N‐aryl itaconimides). A copolymer obtained by taking a mixture of monomers ie MMA:N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 showed a single glass transition temperature. Copyright © 2005 Society of Chemical Industry  相似文献   

13.
The copolymerization of divinyl adipate (DVA) with isobutyl vinyl ether (IBVE) was conducted at 70 and 80 °C in benzene using azobisisobutyronitrile (AIBN), at a concentration as high as 0.50 mol l?1 as the initiator, where the concentrations of DVA and IBVE were 0.40 and 0.60 mol l?1, respectively. The copolymerization proceeded homogeneously, without any gelation, to yield soluble copolymers in spite of the high molar ratio of DVA as an excellent cross‐linker for IBVE. The copolymer yield increased with time, and the number‐average molecular weight (Mn = 0.9–2.4 × 104 g mol?1) from gel permeation chromatography (GPC) and molecular weight distribution (Mw/Mn = 1.5–7.6) of the resulting copolymer increased with copolymer yield. The cyanopropyl group, as a fragment of AIBN, was incorporated as a main constituent in the copolymer, the fraction of which increased from ca 10 to ca 20 % with copolymer yield, hence indicating that the copolymerization is an initiator–fragment incorporation radical polymerization. The copolymers also contained IBVE units (10–30 %) and DVA units with intact double bond (8–36 %) and without double bond (45 %). The intrinsic viscosity of the copolymer was very low (0.1 dl g?1) at 30 °C in tetrahydrofuran. The results from GPC–multi‐angle laser light scattering (MALLS), transmission electron microscopy (TEM) and MALLS revealed that individual copolymer molecules were formed as hyperbranched nanoparticles. Copyright © 2004 Society of Chemical Industry  相似文献   

14.
New functionalized styrene–maleimide copolymers were prepared by free radical copolymerization of styrene (St) and N‐4‐carboxybutylmaleimide (NBMI) in chloroform, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monomer and copolymer characterization was carried out by 1H‐ and 13C‐NMR. Copolymer composition was determined by elemental analysis and Fourier‐transform infrared (FTIR) spectroscopy. The glass transition temperature (from DSC) and the thermogravimetric analysis (TGA) of the copolymers were consistent with the thermal behavior and stability observed for alternating St–maleimide copolymers. St–NBMI copolymers crosslinked with divinylbenzene (DVB) were also synthesized and their cation exchange properties evaluated in order to assess the capacity of the new copolymers to bind metallic ions. Copyright © 2005 Society of Chemical Industry  相似文献   

15.
High rubber styrene–EPDM–acrylonitrile (AES) was prepared by the graft copolymerization of styrene (St) and acrylonitrile (AN) onto ethylene–propylene–diene terpolymer (EPDM) in n‐heptane/toluene cosolvent using benzoyl peroxide as an initiator. The effects of reaction conditions, such as reaction temperature, initiator concentration, EPDM content, the solvent component, and reaction time, on the graft copolymerization are discussed. In addition, according to the research on mechanical properties of the SAN/AES blend, a remarkable toughening effect of AES on SAN resin was found. By means of scanning electron microscopy, the toughening mechanism is proposed to be crazing initiation from rubber particles and shear deformation of SAN matrix. Uniform dispersion of rubber particles, as shown by transmission electron microscopy, is attributed to the good compatibility of SAN and AES. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 416–423, 2004  相似文献   

16.
Poly(methyl methacrylate) (PMMA) was synthesized by activator regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) of MMA in ionic liquid‐based microemulsion with polyoxyethylene sorbitan monooleate (Tween 80) as surfactant. The polymerization was carried out at 25°C with CCl4 as initiator, FeCl3·6H2O/N,N,N′,N′‐tetramethyl‐1,2‐ethanediamine (TMEDA) as catalyst complex in the presence of reducing agent ascorbic acid (VC). The polymerization kinetics showed the feature of controlled/″living″ process as evidenced by a linear first‐order plot. The well‐controlled polymers were obtained with narrow polydispersity indices and the ionic liquid‐based microemulsions were transparent with a particle size less than 30 nm. The obtained polymer was characterized by 1H NMR and gel permeation chromatography. The chain extension was successfully achieved by the obtained PMMA macroinitiator/FeCl3·6H2O/TMEDA/VC initiator system based on ARGET ATRP method. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

17.
Tetramethylpolycarbonate‐block‐poly(styrene‐co‐acrylonitrile) (TMPC‐block‐SAN) block copolymers containing various amounts of acrylonitrile (AN) were examined as compatibilizers for blends of polycarbonate (PC) with poly(styrene‐co‐acrylonitrile) (SAN) copolymers. To explore the effects of block copolymers on the compatibility of PC/SAN blends, the average diameter of the dispersed particles in the blend was measured with an image analyzer, and the interfacial properties of the blends were analyzed with an imbedded fibre retraction technique and an asymmetric double‐cantilever beam fracture test. Reduction in the average diameter of dispersed particles and effective improvement in the interfacial properties was observed by adding TMPC‐block‐SAN copolymers as compatibilizer of PC/SAN blend. TMPC‐block‐SAN copolymer was effective as a compatibilizer when the difference in the AN content of SAN copolymer and that of SAN block in TMPC‐block‐SAN copolymer was less than about 10 wt%. Copyright © 2004 Society of Chemical Industry  相似文献   

18.
Dispersion copolymerization of acrylonitrile‐vinyl acetate (AN‐VAc) had been successfully performed in supercritical carbon dioxide (ScCO2) with 2,2‐azobisisobutyronitrile (AIBN) as a initiator and a series of lipophilic/CO2‐philic diblock copolymers, such as poly(styrene‐r‐acrylonitrile)‐b‐poly(1,1,2,2‐tetrahydroperfluorooctyl methacrylate) (PSAN‐b‐PFOMA), as steric stabilizers. In dispersion copolymerization, poly(acrylonitrile‐r‐vinyl acetate) (PAVAc) was emulsified in ScCO2 effectively using PSAN‐b‐PFOMA as a stabilizer. Compared with the precipitation polymerization (absence of stabilizer), the products prepared by dispersion polymerization possessed of higher yield and higher molecular weight. In addition, the particle morphology of precipitation polymerization was irregular, but the particle morphology of dispersion polymerization was uniform spherical particles. In this study, the effects of the initial concentrations of monomer and the stabilizer and the initiator, and the reaction pressure on the yield and the molecular weight and the resulting size and particle morphology of the colloidal particles were investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5640–5648, 2006  相似文献   

19.
ABS (acrylonitrile–butadiene–styrene) terpolymer is a two-phase thermoplastic with SAN (styrene–acrylonitrile) copolymer constituting the continuous phase (matrix). The flow properties of ABS with varying molecular parameters were studied using a capillary viscometer at the shear rate range encountered in its processing. The viscosity-average molecular weights (Mv) of matrix SAN with 26% acrylonitrile content are in the range of 90,000 to 150,000, and Mv of poly-butadiene-are in the range of 150,000 to 170,000. The weight-average molecular weight of the matrix SAN is the main controlling factor for the flow properties of ABS at low shear rate, while the molecular weight distribution of the matrix SAN becomes increasingly important with the increase of shear rate. The presence of SAN grafted polybutadiene increases the melt viscosity of ABS by 40–60% over comparable free SAN copolymer and also decreases the activation energy at constant shear stress to 24–25 kcal/mole from the 33–36 kcal/mole for free SAN. The die swell of ABS and SAN can be correlated with the dynamic shear modulus G′, and the melt fracture of ABS and SAN starts at G′ equal to 3.6 × 106 dynes/cm2.  相似文献   

20.
A series of experiments were designed and conducted to determine the significance of process parameters in the grafting of styrene and acrylonitrile onto polybutadiene seeds in a semicontinuous emulsion copolymerization system. The significances of the parameters were obtained by comparing the variance ratios, or F values, with F‐distributions. The significance level of each test (α‐value) was obtained by variance analysis. The important process parameters in industrial polymerization processes are usually monomer‐to‐polymer ratio, initiator type and concentration, chain‐transfer agent, and reaction temperature. The target responses were final monomer conversion, grafting degree, grafting efficiency, gel percent, and viscosity‐average molecular weight of free styrene‐acrylonitrile (SAN). The analysis of variance indicated that cumene hydroperoxide as the initiator and reaction temperature had strong effects on the graft structure. Moreover, free SAN molecular weight was significantly affected by the monomer/polymer ratio and cumene hydroperoxide and n‐dodecyl mercaptan as chain‐transfer agents. The raspberry‐like morphology of grafted acrylonitrile‐butadiene‐styrene (ABS) particles and phase separation within the particles were confirmed by transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

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