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1.
In situ Fourier transform near infrared (FTNIR) spectroscopy was successfully used to monitor monomer conversion during copper mediated living radical polymerization with N‐(n‐propyl)‐2‐pyridylmethanimine as a ligand. The conversion of vinyl protons in methacrylic monomers (methyl methacrylate, butyl methacrylate, and N‐hydroxysuccinimide methacrylate) to methylene protons in the polymer was monitored with an inert fiber‐optic probe. The monitoring of a poly(butyl methacrylate‐b‐methyl methacrylate‐b‐butyl methacrylate) triblock copolymer has also been reported with difunctional poly(methyl methacrylate) as a macroinitiator. In all cases FTNIR results correlated excellently with those obtained by 1H NMR. On‐line near infrared (NIR) measurement was found to be more accurate because it provided many more data points and avoided sampling during the polymerization reaction. It also allowed the determination of kinetic parameters with, for example, the calculation of an apparent first‐order rate constant. All the results suggest that FTNIR spectroscopy is a valuable tool to assess kinetic data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4933–4940, 2004  相似文献   

2.
Using an in situ‐generated calcium‐based initiating species derived from pentaerythritol, the bulk synthesis of well‐defined four‐arm star poly(L ‐lactide) oligomers has been studied in detail. The substitution of the traditional initiator, stannous octoate with calcium hydride allowed the synthesis of oligomers that had both low PDIs and a comparable number of polymeric arms (3.7–3.9) to oligomers of similar molecular weight. Investigations into the degree of control observed during the course of the polymerization found that the insolubility of pentaerythritol in molten L ‐lactide resulted in an uncontrolled polymerization only when the feed mole ratio of L ‐lactide to pentaerythritol was 13. At feed ratios of 40 and greater, a pseudoliving polymerization was observed. As part of this study, in situ FT‐Raman spectroscopy was demonstrated to be a suitable method to monitor the kinetics of the ring‐opening polymerization of lactide. The advantages of using this technique rather than FTIR‐ATR and 1H NMR for monitoring L ‐lactide consumption during polymerization are discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4736–4748, 2009  相似文献   

3.
This study describes the preparation of polypyrrole (PPy)/multiwalled carbon nanotube (MWNT) composites by in situ chemical oxidative polymerization. Various ratios of MWNTs, which served as hard templates, were first dispersed in aqueous solutions with the surfactant cetyltrimethylammonium bromide to form micelle/MWNT templates and overcome the difficulty of MWNTs dispersing into insoluble solutions of pyrrole monomer, and PPy was then synthesized via in situ chemical oxidative polymerization on the surface of the templates. Raman spectroscopy, Fourier transform infrared (FTIR), field‐emission scanning electron microscopy (FESEM), and high‐resolution transmission electron microscopy (HRTEM) were used to characterize the structure and morphology of the fabricated composites. Structural analysis using FESEM and HRTEM showed that the PPy/MWNT composites were core (MWNT)–shell (PPy) tubular structures. Raman and FTIR spectra of the composites were almost identical to those of PPy, supporting the idea that MWNTs served as the core in the formation of a coaxial nanostructure for the composites. The conductivities of these PPy/MWNT composites were about 150% higher than those of PPy without MWNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1413–1418, 2006  相似文献   

4.
A new vinyl acyl azide monomer, 4‐(azidocarbonyl) phenyl methacrylate, has been synthesized and characterized by NMR and FTIR spectroscopy. The thermal stability of the new monomer has been investigated with FTIR and thermal gravimetry/differential thermal analysis (TG/DTA), and the monomer has been demonstrated to be stable below 50 °C in the solid state. The copolymerizations of the new monomer with methyl acrylate have been carried out at room temperature under 60Co γ‐ray irradiation in the presence of benzyl 1H‐imidazole‐1‐carbodithioate. The results show that the polymerizations bear all the characteristics of controlled/living free‐radical polymerizations, such as the molecular weight increasing linearly with the monomer conversion, the molecular weight distribution being narrow (<1.20), and a linear relationship existing between ln([M]0/[M]) and the polymerization time. The data from 1H NMR and FTIR confirm that no change in the acyl azide groups has occurred in the polymerization process and that acyl azide copolymers have been obtained. The thermal stability of the polymers has also been investigated with TG/DTA and FTIR. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2609–2616, 2007  相似文献   

5.
In this work, a benzenedinitrile functionalized monomer, 2‐methyl‐acrylic acid 6‐(3,4‐dicyano‐phenoxy)‐hexyl ester, was successfully polymerized via the reversible addition‐fragmentation chain transfer method. The polymerization behavior conveyed the characteristics of “living”/controlled radical polymerization: the first‐order kinetics, linear increase of number‐average molecular weight with monomer conversion, narrow molecular weight distribution, and successful chain‐extension experiment. The soluble Zn(II) phthalocyanine (Pc)‐containing (ZnPc) polymers were achieved by post‐polymerization modification of the obtained polymers. The Zn(II) phthalocyanine‐functionalized polymer was characterized by FTIR, UV–vis, fluorescence, atomic absorption spectroscopy, and thermogravimetric analysis. The potential application of above ZnPc‐functionalized polymer as electron donor material in bulk heterojunction organic solar cell was studied. The device with ITO/PEDOT:PSS/ZnPc‐Polymer/PC61BM/LiF/Al structure provided a power conversion efficiency of 0.014%, fill factor of 0.24, open circuit voltage (Voc) of 0.21 V, and short‐circuit current (Jsc) of 0.28 mA/cm2. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 691–698  相似文献   

6.
A bis(phenylamino)disulfide was prepared through the reaction of S2Cl2 with aniline, and its configuration was confirmed with elemental analysis, Fourier transform infrared (FTIR), Fourier transform Raman (FT‐Raman), and 1H NMR spectroscopy. A novel conducting polymer, poly[bis(phenylamino)disulfide] (PPAD), was synthesized from bis(phenylamino)disulfide by both chemical and electrochemical polymerization. The structure of this polymer, in which the side‐chain disulfide bonds were linked to the nitrogen atoms of the main‐chain polyaniline, was characterized with FTIR, FT‐Raman, gel permeation chromatography, electron spectroscopy, and X‐ray photoelectron spectroscopy. A four‐probe measurement revealed that the electrical conductivity of PPAD was 1.8 × 10?2 to 2.1 × 10?3 S cm?1, depending on the doping agents and the pH of the medium for either chemical synthesis or electrochemical synthesis. The conductivity, molecular weight, and spectroscopic properties of the polymer, in comparison with those of polyaniline, showed decreases in the polaron delocalization, structural order, and doping level of the main chain because of the steric hindrance of side‐chain S? S bonds. The cyclic voltammograms of the polymer and the monomer showed that the redox reactions (doping/undoping processes) of the main chain (π‐conjugated system) occurred in almost the same potential range of ?0.3 to 0.3 V versus an Ag/AgCl (saturated KCl) electrode as that of thiol (thiolate anion)/disulfide of the side chain in PPAD; the bond cleavage (reduction) and formation (oxidation) reactions of the disulfide bond in the polymer became easier and more reversible than those of the monomer. These results suggested that this conducting organodisulfide polymer might be a candidate material for energy‐storage devices such as lithium secondary batteries, proton‐exchange batteries, and electrochemical capacitors. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2329–2339, 2004  相似文献   

7.
Reversible addition‐fragmentation chain transfer (RAFT) miniemulsion polymerization of butyl methacrylate (BMA) and dodecafluoroheptyl methacrylate (DFMA) was carried out with 2‐cyanoprop‐2‐yl dithiobenzoate (CPDB) as chain transfer agent (CTA). Concentration effects of RAFT agent and initiator on kinetics and molecular weight were investigated. No obvious red oil layer (phase's separation) and coagulation was observed in the first stage of homopolymerization of BMA. The polymer molecular weights increased linearly with the monomer conversion with polydispersities lower than 1.2. At 75 °C, the monomer conversion could achieve above 96% in 3 h with [momomer]:[RAFT]:[KPS] = 620:4:1 (mole ratio). The results showed excellent controlled/living polymerization characteristics and a very fast polymerization rate. Furthermore, the synthesis of poly(BMA‐b‐DFMA) diblock copolymers with a regular structure (PDI < 1.30, PMMA calibration) was performed by adding the monomer of DFMA at the end of the RAFT miniemulsion polymerization of BMA. The success of diblock copolymerization was showed by the molecular weight curves shifting toward higher molar mass, recorded by gel permeation chromatography before and after block copolymerization. Compositions of block copolymers were further confirmed by 1H NMR, FTIR, and DSC analysis. The copolymers exhibited a phase‐separated morphology and possessed distinct glass transition temperatures associated with fluoropolymer PDFMA and PBMA domains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1585–1594, 2007  相似文献   

8.
In this work, Fe(0)‐mediated single electron‐living radical copolymerization of styrene (St) and acrylamide (AM) was investigated at ambient temperature in N,N‐dimethylformamide using carbon tetrachloride as initiator and tetramethylethylenediamine as ligand. Kinetic studies showed that the copolymerization followed the first‐order kinetics model. The resulting copolymers of St and AM possessed predetermined molecular weights and narrow molecular weight distribution, which agreed with the character of controlled/living polymerization. On the basis of Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (NMR), the monomer reactivity ratios were calculated. The amount of ligand played an important role in copolymerization. The obtained polymer was characterized by FTIR, 1H NMR, 13C NMR, and gel permeation chromatography. The living characteristics were demonstrated by chain extension experiment. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2919–2924  相似文献   

9.
The in situ grafting‐from approach via atom transfer radical polymerization was successfully applied to polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile grafted onto the convex surfaces of multiwalled carbon nanotubes (MWCNTs) with (2‐hydroxyethyl 2‐bromoisobutyrate) as an initiator. Thermogravimetric analysis showed that effective functionalization was achieved with the grafting approach. The grafted polymers on the MWCNT surface were characterized and confirmed with Fourier transform infrared spectroscopy and nuclear magnetic resonance. Raman and near‐infrared spectroscopy revealed that the grafting of polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile slightly affected the side‐wall structures. Field emission scanning electron microscopy showed that the carbon nanotube surface became rough because of the grafting of the polymers. Differential scanning calorimetry results indicated that the polymers grafted onto MWCNTs showed higher glass‐transition temperatures. The polymer‐grafted MWCNTs exhibited relatively good dispersibility in an organic solvent such as tetrahydrofuran. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 460–470, 2007  相似文献   

10.
An in situ ultrasonic spectroscopy technique was used to study the ring‐opening metathesis polymerization of dicyclopentadiene catalyzed by bis(tricyclohexylphosphine)benzylidene ruthenium dichloride. A reaction cell employing a flexible poly(ethylene terephthalate) window for pulse echo ultrasonic spectroscopy was used to monitor the polymerization. The changes in the density, wave speed, acoustic modulus, and attenuation were all simultaneously monitored. In comparison with Fourier transform infrared (FTIR) spectroscopy data, the changes in the density, velocity, and modulus only accurately measured the rate constant for the metathesis of the cyclopentyl unsaturation. The ultrasonic values were within 6% of the values determined by FTIR. The activation energy for metathesis of the cyclopentyl unsaturation was 84 kJ mol?1, following first‐order kinetics. Rate constants for the polymerization of the norbornyl unsaturation could not be determined by ultrasound. The gel point, vitrification, and qualitative information about the reaction rate could be determined from the change in the attenuation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1323–1333, 2003  相似文献   

11.
A new polythiophene derivative was synthesized by both chemical and electrochemical oxidative polymerization of 1‐(1‐phenylethyl)‐2,5‐di(2‐thienyl)‐1H‐pyrrole (PETPy). Of which the chemical method produces a polymer that is completely soluble in organic solvents. The structures of both the monomer and the soluble polymer were elucidated by nuclear magnetic resonance (1H and 13C NMR) and Fourier transform infrared (FTIR) spectroscopy. The average molecular weight has been determined by gel permeation chromatography to be Mn = 3.29 × 103 for the chemically synthesized polymer. Polymer of PETPy was synthesized via potentiostatic electrochemical polymerization in acetonitrile (AN)/NaClO4/LiClO4 (0.1 M) solvent–electrolyte couple. Characterizations of the resulting polymer were performed by cyclic voltammetry, FTIR, scanning electron microscopy, and UV–vis spectroscopy. Four‐probe technique was used to measure the conductivities of the samples. Moreover, the spectroelectrochemical and electrochromic properties of the polymer films were investigated. In addition, dual‐type polymer electrochromic devices based on P(PETPy) with poly(3,4‐ethylenedioxythiophene) were constructed. Spectroelectrochemistry, electrochromic switching, and open circuit stability of the devices were studied. They were found to have good switching times, reasonable contrasts, and optical memories. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2215–2225, 2006  相似文献   

12.
Thermosensitive crosslinked polymer latexes have been synthesized by precipitation polymerization of N-isopropylmethacrylamide (NIPMAM) as a main monomer, methylene bis-acrylamide (MBA) as a crosslinker, and potassium persulfate (KPS) as the initiator. Polymerizations kinetics were first investigated by studying both the influence of crosslinker (MBA) and initiator (KPS) concentrations and temperature effects on the polymerization conversion, the particle size, and water-soluble polymer (WSP) as a function of time. Particle size analysis by Scanning Electron Microscopy (SEM) showed that a short nucleation step afforded the synthesis of highly monodispersed latexes. In addition, a strong dependence of WSP formation on MBA and KPS concentration and polymerization temperature was found, as well. Comparison of particle size by SEM and quasielastic light scattering clearly evidenced the dramatic effect of temperature on particle size. Lower critical solubility temperatures (LCST) of latexes were determined and compared. Finally, based on these results, the mechanism of particle formation in this polymerization process is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1823–1837, 1999  相似文献   

13.
The copolymerization of α-methylene-γ-butyrolactone and methyl methacrylate in DMSO was studied by on-line Raman spectroscopy. Reactivity ratios for this system were estimated from the in situ conversion measurements. The estimates are in good agreement with estimates obtained from low-conversion experiments where the composition of the copolymer was analyzed by 1H-NMR. In order to obtain reliable estimates from the Raman data in combination with the integrated copolymerization equation, at least two experiments starting from different initial monomer feed fractions should be conducted. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3804–3816, 1999  相似文献   

14.
The bulk polymerization of methyl methacrylate initiated with 2‐pyrrolidinone and n‐dodecyl mercaptan (R‐SH) has been explored. This polymerization system showed “living” characteristics; for example, the molecular weight of the resulting polymers increased with reaction time by gel permeation chromatographic analysis. Also, the polymer was characterized by Fourier transform infrared spectroscopy, 1H NMR, and 13C NMR techniques. The polymer end with the iniferter structures was found. By the initial‐rate method, the polymerization rate depended on [2‐pyrrolidinone]1.0 and [R‐SH]0. Combining the structure analysis and the polymerization‐rate expression, a possible mechanism was proposed. n‐Dodecyl mercaptan served dual roles—as a catalyst at low conversion and as a chain‐transfer agent at high conversion. Finally, the thermal properties were studied, and the glass‐transition temperature and thermal‐degradation temperature were, respectively, 25 and 80–100 °C higher than that of the azobisisobutyronitrile system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3692–3702, 2002  相似文献   

15.
For the first time, stabilizer‐free vinylidene fluoride (VDF) homopolymerizations were carried out in homogenous phase with supercritical CO2 using the conventional initiator di‐tert butyl peroxide (DTBP). In‐line FT‐NIR spectroscopy showed that complete monomer conversion may be obtained. Molecular weights were determined via size‐exclusion chromatography and polymer endgroup analysis by 1H‐NMR spectroscopy. The number average molecular weights were below 104 g mol?1 and polydispersities ranged from 3.1 to 5.7 depending on DTBP and VDF concentration. For allowing isothermal reaction, high CO2 contents ranging from 61 to 83 wt % were used. The high‐temperature and high‐pressure conditions required for homogeneous polymerization did not alter the amount of defects in VDF chaining. Scanning electron microscopy indicated that regular stack‐type particles are obtained upon expansion of the homogeneous polymerization mixture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5626–5635, 2007  相似文献   

16.
Monofunctional benzoxazine with ortho‐methylol functionality has been synthesized and highly purified. The chemical structure of the synthesized monomer has been confirmed by 1H and 13C nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT‐IR) and elemental analysis. One‐dimensional (1D) 1H NMR is used with respect to varied concentration of benzoxazines to study the specific nature of hydrogen bonding in both ortho‐methylol functional benzoxazine and its para counterpart. The polymerization behavior of benzoxazine monomer has been also studied by in situ FT‐IR and differential scanning calorimetry, experimentally supporting the polymerization mechanism of ortho‐methylol functional benzoxazine we proposed before. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3635–3642  相似文献   

17.
The electropolymerization of trans-[RuCl2(vpy)4] (vpy=4-vinylpyridine) monomer on Nd-Fe-B magnets was studied by electrochemical impedance spectroscopy (EIS). Impedance diagrams obtained during the polymerization process were used to monitor film formation. The EIS results gave insight into the electrochemical phenomena occurring at the magnet surface as the polymerization process progressed. The film structure and morphology were also studied by X-ray photoelectron spectroscopy, scanning electron microscopy and Raman spectroscopy. The Raman spectroscopy results showed that the polymerization takes place at the vinyl groups of the monomer and also that the redox polymer structure is very similar to that of the monomer. The ratio of the intensity of the XPS peaks for fluorine (from the electrolyte PF6 ) and ruthenium present in the film showed that the polymer on Nd-Fe-B contained an equal proportion of Ru2+ and Ru3+, indicating that part of the film is positively charged, i.e. {[RuCl2(vpy)4]+} n .  相似文献   

18.
The amphiphilic poly(AM‐co‐SA)‐ITXH macrophotoinitiator was synthesized by precipitation photopolymerization under UV irradiation with isopropylthioxanthone (ITX) as free radical photoinitiator. A novel method has been developed to prepare amphiphilic core‐shell polymer nanospheres via photopolymerization of methyl methacrylate (MMA) in aqueous media, with amphiphilic copolymer macrophotoinitiator poly(AM‐co‐SA)‐ITXH. During polymerization, the amphiphilic macroradicals underwent in situ self‐assembly to form polymeric micelles, which promoted the emulsion polymerization of the monomer. Thus, amphiphilic core‐shell nanospheres ranging from 70 to 140 nm in diameter were produced in the absence of surfactant. The conversion of the monomer, number average molecular weights (Mn), and particle size were found to be highly dependent on the macrophotoinitiator and monomer concentration. The macrophotoinitiator and amphiphilic particles were characterized by FTIR, UV‐vis, 1H NMR, TEM, DSC, and contact angle measurements. The results showed the particles had well‐defined amphiphilic core‐shell structure. This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic core‐shell nanospheres. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 936–942, 2010  相似文献   

19.
The feasibility of utilizing stable free‐radical polymerization (SFRP) in the synthesis of well‐defined poly(2‐vinylnaphthalene) homopolymers has been investigated. Efforts to control molecular weight by manipulating initiator concentration while maintaining a 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO):benzoyl peroxide (BPO) molar ratio of 1.2:1 proved unsuccessful. In addition, systematic variations of the TEMPO: BPO molar ratio did not result in narrow molecular weight distributions. In situ Fourier transform infrared spectroscopy (FTIR) indicated that the rate of monomer disappearance under SFRP and thermal conditions were identical. This observation indicated a lack of control in the presence of the stable free radical, TEMPO. The similarities in chemical structure between styrene and 2‐vinylnaphthalene suggested thermally initiated polymerization occurred via the Mayo mechanism. A kinetic analysis of the thermal polymerization of styrene and 2‐vinylnaphthalene suggested that the additional fused ring in 2‐vinylnaphthalene increased the propensity for thermal polymerization. The observed rate constant for thermal polymerization of 2‐vinylnaphthalene was determined using in situ FTIR spectroscopy and was one order of magnitude greater than styrene, assuming pseudo‐first‐order kinetics. Also, an Arrhenius analysis indicated that the activation energy for the thermal polymerization of 2‐vinylnaphthalene was 30 kJ/mol less than styrene. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 583–590, 2002; DOI 10.1002/pola.10131  相似文献   

20.
A functional monomer with a pendant azide moiety, 2‐azidoethyl methacrylate (AzMA), was polymerized via reversible addition‐fragmentation chain transfer (RAFT) polymerization with excellent control over the molecular weight distribution (PDI = 1.05–1.15). The subsequent copper‐catalyzed Huisgen 1,3‐dipolar cycloadditions of phenyl acetylene with polyAzMA was achieved at room temperature with high conversion. The resulting functional polymer exhibited identical 1H NMR and IR spectra with the polymer of the same molecular structure but prepared by a prefunctionalization approach, confirming the retention of the azide side chains during the RAFT polymerization of AzMA. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4300–4308, 2007  相似文献   

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