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1.
Glycidylmethacrylate/vinyl acetate copolymers were prepared by solution polymerization with benzene as a solvent and benzoyl peroxide as an initiator. Copolymer compositions were determined from 1H NMR spectra, and comonomer reactivity ratios were determined by the Kelen–Tudos (KT) method and the nonlinear least‐squares error‐in‐variable method (EVM). The reactivity ratios obtained from KT and EVM were rG = 37.4 ± 12.0 and rV = 0.036 ± 0.019 and rG = 35.2 and rV = 0.03, respectively. Complete spectral assignments of 13C and 1H NMR spectra were done with the help of distortionless enhancement by polarization transfer and two‐dimensional 13C–1H heteronuclear single quantum coherence and total correlation spectroscopy. The methyl, methine, and methylene carbon resonance showed both stereochemical and compositional sensitivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4051–4060, 2001  相似文献   

2.
Trans-4-methacryloyloxyazobenzene/Vinylidene Chloride (M/V) copolymers of different monomer concentrations were prepared by solution polymerization using benzoyl peroxide as an initiator. The copolymer composition was determined from the 13C{1H}-NMR spectrum. The quaternary carbon of M- and V-centered resonances were used for determining the sequences in terms of the distribution of M- and V-centered triads. The sequence distribution of M- and V-centered triads determined from 13C{1H}-NMR spectra of the copolymer is in good agreement with the triad concentration calculated from the statistical model. The comonomer reactivity ratios, determined by both the Kelen Tudos (KT) and the nonlinear error in variables (EVM) methods are rM = 3.59 ± 0.19, rV = 0.89 ± 0.07; rM = 3.76, and rV = 0.93, respectively. 13C Distortionless Enhancement by Polarization Transfer (DEPT) spectrum was used to differentiate between the resonance signals of M- and V-methylene and methyl carbon units. Assignments to the methylene resonance signals have been assigned up to the tetrad levels using 2D HSQC experiments. The geminal couplings in the methylene proton region is shown in the 2D DQF-COSY spectrum. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3179–3185, 1999  相似文献   

3.
(Vinyl acetate)/(ethyl acrylate) (V/E) and (vinyl acetate)/(butyl acrylate) (V/B) copolymers were prepared by free radical solution polymerization. 1H-NMR spectra of copolymers were used for calculation of copolymer composition. The copolymer composition data were used for determining reactivity ratios for the copolymerization of vinyl acetate with ethyl acrylate and butyl acrylate by Kelen-Tudos (KT) and nonlinear Error in Variables methods (EVM). The reactivity ratios obtained are rv = 0.03 ± 0.03, rE = 4.68 ± 1.70 (KT method); rv = 0.03 ± 0.01, rE = 4.60 ± 0.65 (EV method) for (V/E) copolymers and rv ? 0.03 ± 0.01, rB ? 6.67 ± 2.17 (KT method); rv = 0.03 ± 0.01, rB = 7.43 ± 0.71 (EV method) for (V/B) copolymers. Microstructure was obtained in terms of the distribution of V- and E-centered triads and V- and B-centered triads for (V/E) and (V/B) copolymers respectively. Homonuclear 1H 2D-COSY NMR spectra were also recorded to ascertain the existence of coupling between protons in (V/E) as well as (V/B) copolymers. © 1995 John Wiley & Sons, Inc.  相似文献   

4.
The new acrylic monomer 4‐propanoylphenyl acrylate (PPA) was synthesized and copolymerized with methyl methacrylate (MMA) in methyl ethyl ketone at 70±1°C using benzoyl peroxide as a free radical initiator. The copolymers were characterized by FT‐IR, 1H‐NMR and 13C‐NMR spectroscopic techniques. The compositions of the copolymers were determined by 1H‐NMR analysis. The reactivity ratios of the monomers were determined using Fineman‐Ross (r1=0.5535 and r2=1.5428), Kelen‐Tüdös (r1=0.5307 and r2=1.4482), and Ext. Kelen‐Tüdös (r1=0.5044 and r2=1.4614), as well as by a nonlinear error‐in‐variables model (EVM) method using a computer program, RREVM (r1=0.5314 and r2=1.4530). The solubility of the polymers was tested in various polar and non‐polar solvents. The elemental analysis was determined by a Perkin‐Elmer C‐H analyzer. The molecular weights (Mw and Mn) of the copolymers were determined by gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of MMA in the copolymers. Glass transition temperatures of the copolymers were found to increase with an increase in the mole fraction of MMA in the copolymers.  相似文献   

5.
Radical-initiated copolymerization of N-isopropylacrylamide (NIPA) with maleic (MA) and citraconic (CA) anhydrides was carried out in the presence of 2,2-azobisisobutyronitrile (AIBN) as an initiator in 1,4-dioxane at 65 °C under nitrogen atmosphere. Structure and monomer unit compositon of the copolymers obtained from a wide range of monomer feed were determined by elemental analysis (content of N for NIPA units), Fourier transform infrared and 1H NMR spectroscopy. Monomer reactivity ratios for NIPA (M1)-MA (M2) and NIPA (M1)-CA (M2) pairs were determined by Kelen-Tüdõs (KT) and non-linear regression (NLR) methods using elemental and 1H NMR spectroscopy analyses data. They are r1=0.45 and r2=0.08 (KT, N analysis), r1=0.44 and r2=0.10 (KT, 1H NMR), r1=0.45 and r2=0.078 (NLR) for NIPA-MA monomer pair and r1=0.52 and r2=0.02, r1=0.44 and r2=0.04, r1=0.51 and r2=0.014 for NIPA-CA monomer pair, respectively. Observed tendency towards alternating copolymerization at ?50 mol% NIPA concentration in monomer feed and relatively high activity of NIPA growing radical was explained by H-bond formation between CO (anhydride) and NH (amide) fragments during chain growth reactions. Intrinsic viscosity, molecular weight and thermal behaviour of the synthesized copolymers were found to depend on the type of comonomer and the amount of NIPA units in the copolymers. These functional amphiphilic copolymers containing anion- and cation-active groups show both temperature and pH sensitivity and can be used for biological purposes as physiologically active macromolecular systems.  相似文献   

6.
Acrylonitrile/pentyl acrylate (A/P) copolymers of different monomer composition were prepared by solution polymerization using benzoyl peroxide as initiator. Copolymer compositions were determined by elemental analysis and quantitative 13C1H‐NMR spectroscopy. The comonomer reactivity ratios, determined by both Kelen Tudos (KT) and nonlinear error in variables (EVM) methods are rA = 0.75 and rp = 0.45. 2‐D heteronuclear correlation spectroscopy (HSQC) was used to simplify the complex 1H spectra of A/P copolymers in terms of configurational and compositional sequences. The microstructure was obtained in terms of the distribution of A‐ and P‐ centered triad sequences from 13C1H‐NMR spectra of the copolymers. The copolymerization mechanism was found to follow a first order Markov Model. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 533–543, 1999  相似文献   

7.
2-Hydroxypropyl methacrylate (2 HPMA) has been copolym-erized with ethyl methacrylate (EMA), n-butyl methacrylate (BMA), and 2-ethylhexyl methacrylate (EHMA) in bulk at 60°C using benzoyl peroxide as initiator. The copolymer composition has been determined from the hydroxyl content. The reactivity ratios have been calculated by the YBR method. For copolymerization of 2-HPMA (M1) with EMA (M2), the reactivity ratios are: r1=1.807 ± 0.032, r2=0.245 ± 0.021; with BMA (M2) they are r1=2.378 ± 0.001, r2=0.19 ± 0.01; and with EHMA the values are r1=4.370 ± 0.048, r2=0.103 ± 0.006. Since the reactivity ratios are the measure of distribution of monomer units in a copolymer chain, the values obtained are compared and discussed. This enables us to choose a suitable copolymer for synthesizing thermoset acrylic polymers, which are obtained from cross-linking of hydroxy functional groups of HPMA units, for specific end uses.  相似文献   

8.
Abstract

4‐(3′,4′‐Dimethoxycinnamoyl)phenyl acrylate (DMCPA) containing pendant chalcone moiety was copolymerized with methyl methacrylate (MMA) by radical polymerization in ethyl methyl ketone at 70°C under a nitrogen atmosphere using benzoyl peroxide (BPO) as a free radical initiator. The prepared polymer was characterized by UV, FT‐IR, 1H‐NMR, and 13C‐NMR spectra. The composition of the copolymer was determined using 1H‐NMR analysis. The monomer reactivity ratios of copolymerization were determined using conventional linearization methods such as Fineman–Ross (r 1 = 0.26 and r 2 = 0.61), Kelen–Tudos (r 1 = 0.26 and r 2 = 0.61), and Ext. Kelen–Tudos (r 1 = 0.23 and r 2 = 0.59), and a non‐linear error‐in‐variables model (EVM) method using the computer program RREVM (r 1 = 0.2541 and r 2 = 0.6094). The molecular weights (M w and M n) of the copolymers were determined by gel permeation chromatography. Thermogravimetric analysis of the polymers in air reveals that the stability of the copolymers decreases with an increase in the mole fraction of MMA in the copolymers. The solubility of the polymers was tested in various polar and non‐polar solvents. The glass transition temperature of the copolymers was determined as a function of copolymer composition. The copolymers were sensitive to UV light and became crosslinked after irradiation with 254 nm light.  相似文献   

9.
Ca2+ complexation by both sulfate and selenate ligands was studied by CE. The species were observed to give a unique retention peak as a result of a fast equilibrium between the free ions and the complexes. The change in the corresponding retention time was interpreted with respect to the equilibrium constant of the complexation reaction. The results confirmed the formation of CaSO4(aq) and CaSeO4(aq) under our experimental conditions. The formation data were derived from the series of measurements carried out at about 15, 25, 35, 45 and 55°C in 0.1 mol/L NaNO3 ionic strength solutions, and in 0.5 and 1.0 mol/L NaNO3 ionic strength solutions at 25°C. Using a constant enthalpy of reaction enabled to fit all the experimental data in a 0.1 mol/L medium, leading to the thermodynamic parameters: ΔrG0.1M(25°C)=?(7.59±0.23) kJ/mol, ΔrH0.1 M=5.57±0.80 kJ/mol, and ΔrS0.1 M(25°C)=44.0±3.0 J mol?1 K?1 for CaSO4(aq) and ΔrG0.1 M(25°C)=?(6.66±0.23) kJ/mol, ΔrH0.1 M=6.45±0.73 kJ/mol, and ΔrS0.1 M(25°C)=44.0±3.0 J mol?1 K?1 for CaSeO4(aq). Both formation reactions were found to be endothermic and entropy driven. CaSO4(aq) appears to be more stable than CaSeO4(aq) by 0.93 kJ/mol under these experimental conditions, which correlates with the difference of acidity of the anions as expected for interactions between hard acids and hard bases according to the hard and soft acids and bases theory. The effect of the ionic medium on the formation constants was successfully treated using the Specific ion Interaction Theory, leading to significantly different binary coefficients mol/kg?1 and mol/kg?1  相似文献   

10.
Variable temperature (?55 to ?105 °C) studies of the infrared spectra (4000–400 cm?1) of chlorocyclohexane (c-C6H11Cl) dissolved in liquefied xenon have been carried out. The infrared spectra of the gas and solid have also been recorded from 4000–100 cm?1. By analyzing six conformer pairs in the xenon solution, a standard enthalpy difference of 132 ± 13 cm?1 (1.58 ± 0.16 kJ/mol) was obtained with the equatorial conformer the more stable form. At ambient temperature, the abundance of the axial conformer is 34 ± 1%. The potential surface describing the conformational interchange has been determined and the Fourier coefficients were obtained. From MP2 ab initio calculations utilizing various basis sets with and without diffuse functions, the equatorial conformer is predicted to be more stable by 161 ± 18 cm?1 from the four largest basis set calculations, which is consistent with the experimental results. However, the average from the corresponding B3LYP density functional theory calculations is 274 ± 15 cm?1 which is certainly too large. By utilizing the previously reported microwave rotational constants for two isotopomers (35Cl, 37Cl) combined with the structural parameters predicted from the MP2(full)/6-311+G(d,p) calculations, adjusted r 0 structural parameters have been obtained. The determined heavy atom distances for the most stable chair-equatorial conformer in Å are: r 0(C1–C7,8) = 1.532(3); r 0(C7,8–C13,14) = 1.536(3); r 0(C4–C13,14) = 1.524(3); and r 0(C4–Cl6) = 1.802(5) and the angles in degrees: ∠C1C7,8C13,14 = 111.3(5)º; ∠Cl6C4C13,14 = 109.7(5)º with the two dihedral angles ∠C8C1C7C13 = 56.3(10)º and ∠C14C4C13C7 = 56.7(10)º. These parameters are in good agreement with those reported earlier from microwave and electron diffraction studies where the CC and CH distances were all assumed to be equal. A few of the previously reported vibrational assignments have been corrected. The results of these spectroscopic and theoretical studies are discussed and compared to the corresponding results for some similar molecules.  相似文献   

11.
The conformational preference of the methyl group of 1-methyl-1-germacyclohexane was studied experimentally in solution (low-temperature 13C NMR) and by quantum chemical calculations (CCSD(T), MP2 and DFT methods). The NMR experiment resulted in an axial/equatorial ratio of 44/56 mol% at 114 K corresponding to an A value (A = G ax G eq) of 0.06 kcal mol?1. An average value for ΔG e→a #  = 5.0 ± 0.1 kcal mol?1 was obtained for the temperature range 106–134 K. The experimental results are very well reproduced by the calculations. CCSD(T)/CBS calculations + thermal corrections resulted in an A value of 0.02 kcal mol?1, whereas a ΔE value of ?0.01 kcal mol?1 at 0 K was obtained.  相似文献   

12.

A new methacrylic monomer, 4‐nitro‐3‐methylphenyl methacrylate (NMPM) was prepared by reacting 4‐nitro‐3‐methyl phenol dissolved in methyl ethyl ketone (MEK) in the presence of triethylamine as a catalyst. Copolymerization of NMPM with methyl methacrylate (MMA) has been carried out in methyl ethyl ketone (MEK) by free radical solution polymerization at 70±1°C utilizing benzoyl peroxide (BPO) as initiator. Poly (NMPM‐co‐MMA) copolymers were characterized by FT‐IR, 1H‐NMR and 13C‐NMR spectroscopy. The molecular weights (Mw and Mn) and polydispersity indices (Mw/Mn) of the polymers were determined using a gel permeation chromatograph. The glass transition temperatures (Tg) of the copolymers were determined by a differential scanning calorimeter, showing that Tg increases with MMA content in the copolymer. Thermogravimetric analysis of the polymers, performed under nitrogen, shows that the stability of the copolymer increases with an increase in NMPM content. The solubility of the polymers was tested in various polar and non‐polar solvents. Copolymer compositions were determined by 1H‐NMR spectroscopy by comparing the integral peak heights of well separated aromatic and aliphatic proton peaks. The monomer reactivity ratios were determined by the Fineman‐Ross (r1 =7.090:r2=0.854), Kelen‐Tudos (r1=7.693: r2=0.852) and extended Kelen‐Tudos methods (r1=7.550: r2= 0.856).  相似文献   

13.
Copolymerization of acrylonitrile (AN) with itaconic acid (IA) in dimethylformamide (DMF) and DMF/water mixture was investigated at enhanced concentrations of the latter. Analysis of the copolymer composition revealed the existence of a marked penultimate unit effect with respect to radicals terminated in AN. The reactivity of IA was considerably less than that of AN, manifested as a negative reactivity ratio for the former. The rIA values ranging from −0.28 to −0.50 and rAN values ranging from 0.53 to 0.70, were obtained by Kelen-Tudo's (KT) and extended KT methods. The penultimate reactivity ratios were determined by both linear and non-linear methods. The values ranged from r1=0.009 to 0.01, r1=0.0015 to 0.0043, r2=0.54 to 0.69 and r2=0.9 to 1.03. The reactivity of AN radical towards IA decreased about twofold when the latter formed the penultimate group. The penultimate model explained an acceptable rational feed-copolymer composition profile for the whole composition range. Addition of water decreased the reactivity of IA slightly. IA caused a decrease in the apparent copolymerization rate in agreement with the observed trends in the reactivity ratios; presence of water caused a further decrease in the rate of polymerization. A statistical prediction of monomer sequences based on reactivity ratios implied that IA existed as a lone monomer unit between the long sequences of AN units.  相似文献   

14.
Copolymers of styrene and methyl methacrylate were synthesized by atom transfer radical polymerization using methyl 2‐bromopropionate as initiator and CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalyst. Molecular weight distributions were determined by gel permeation chromatography. The composition of the copolymer was determined by 1H NMR. The comonomer reactivity ratios, determined by both Kelen–Tudos and nonlinear error‐in‐variables methods, were rS = 0.64 ± 0.08, rM = 0.63 ± 0.08 and rS = 0.66, rM = 0.65, respectively. The α‐methyl and carbonyl carbon resonances were found to be compositionally and configurationally sensitive. Complete spectral assignments of the 1H and 13C NMR spectra of the copolymers were done by distortionless enhancement by polarization transfer and two‐dimensional NMR techniques such as heteronuclear single quantum coherence and heteronuclear multiple quantum coherence. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2076–2085, 2006  相似文献   

15.
Methacrylonitrile-styrene-methyl methacrylate (N/S/M) terpolymers of different monomer concentrations were prepared by bulk polymerization. The terpolymer compositions were determined by quantitative 13C{1H} NMR spectra and compared with those calculated by Goldfinger's equation using comonomer reactivity ratios: rNS=0.30, rSN=0.45; rNM=0.91, rMN=0.88; rSM=0.52, rMS=0.47. The overlapping and complex 13C{1H} and 1H NMR spectra of the terpolymers were assigned with the help of distortionless enhancement by polarization transfer and two-dimensional (2D) 13C-1H heteronuclear single quantum coherence experiments. The various vicinal and geminal couplings between the protons in the polymer chains can be seen in the 2D total correlated spectroscopy experiments.  相似文献   

16.
2-Hydroxypropyl methacrylate (2-HPMA) has been copolym-erized with ethyl methacrylate (EMA), n-butyl methacrylate (BMA), and 2-ethylhexyl methacrylate (EHMA) in bulk at 60°C using benzoyl peroxide as initiator. The copolymer composition has been determined from the hydroxyl content. The reactivity ratios have been calculated by the Yezrielev, Brokhina, and Raskin method. For copolymerization of 2-HPMA (M1) with EMA (M2), the reactivity ratios are r1 = 1.807 ± 0.032 and r2 = 0.245 ± 0.021; with BMA (M2) they are n = 2.378 ± 0.001 and r2 = 0.19 ± 0.01; and with EHMA the values are r1 = 4.370 ± 0.048 and r2 = 0.103 ± 0.006. Since reactivity ratios are the measure of distribution of monomer units in copolymer chain, the values obtained are compared and discussed. This enables us to choose a suitable copolymer for synthesizing thermoset acrylic polymers, which are obtained from cross-linking of hydroxy functional groups of HPMA units, for specific end-uses.  相似文献   

17.
18.
Copolymers of 2-sulfoethyl methacrylate, (SEM) were prepared with ethyl methacrylate, ethyl acrylate, vinylidene chloride, and styrene in 1,2-dimethoxyethane solution with N,N′-azobisisobutyronitrile as initiator. The monomer reactivity ratios with SEM (M1) were: vinylidene chloride, r1 = 3.6 ± 0.5, r2 = 0.22 ± 0.03; ethyl acrylate, r1 = 3.2 ± 0.6, r2 = 0.30 ± 0.05; ethyl methacrylate, r1 = 2.0 ± 0.4, r2 = 1.0 ± 0.1; styrene, r1 = 0.6 ± 0.2, r2 = 0.37 ± 0.03. The values of the copolymerization parameters calculated from the monomer reactivity ratios were e = +0.6 and Q = 1.4. Comparison of the monomer reactivities indicates that SEM is similar to ethyl methacrylate with regard to copolymerization reactivity in 1,2-dimethoxyethane solution. The sodium salt of 2-sulfoethyl methacrylate, SEM?Na, was copolymerized with 2-hydroxyethyl methacrylate (M2) in water solution. Reactivity ratios of r1 = 0.7 ± 0.1 and r2 = 1.6 ± 0.1 were obtained, indicating a lower reactivity of SEM?Na in water as compared to SEM in 1,2-dimethoxyethane. This decreased reactivity was attributed to greater ionic repulsion between reacting species in the aqueous medium.  相似文献   

19.
Copolymers with various contents of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone (MPDSK) and methyl methacrylate (MMA) were prepared in methyl ethyl ketone solution using benzoyl peroxide as a free radical initiator at 70 °C. Characterization of the resulting polymers was done by UV, FT-IR, 1H NMR and 13C NMR spectroscopic techniques. The copolymer compositions were determined by 1H NMR analysis. The monomer reactivity ratios were calculated using linearisation methods such as Finemann-Ross (r1 = 0.4283 and r2 = 0.3050), Kelen-Tudos (r1 = 0.4264 and r2 = 0.2606), and extended Kelen-Tudos (r1 = 0.4022 and r2 = 0.2704) methods as well as by a non-linear error-in-variables model (EVM) method using the computer program RREVM (r1 = 0.4066 and r2 = 0.2802). The molecular weights ( and ) and the polydispersity index of the copolymers were determined by gel permeation chromatography. The thermal stability of the copolymers increases with increase in concentration of MPDSK. Glass transition temperatures were determined by differential scanning calorimeter under nitrogen atmosphere. The photoreactivity of the copolymers having pendant chalcone moieties was studied in chloroform solution.  相似文献   

20.
Phosphorus pentafluoride-catalyzed copolymerization of 1,6-anhydro-2,3,4-tri-O-(p-methylbenzyl)-β-D -glucopyranose (TXGL, monomer G) and 1,6-anhydro-2,3,4-tri-O-benzyl-β-D -mannopyranose (TBMN, monomer M) appears to follow classical copolymerization theory. Reactivity ratios calculated by the procedure of Mayo and Lewis were rG = 0.90 ± 0.08, rM = 11.5 ± 0.80, from which sequence distributions were calculated. A conformational analysis of anhydro sugar polymerization is presented to explain differences in reactivity of monomers and their derived cations in polymerization and copolymerization. The polymers and copolymers were characterized by viscosity, 1H- and 13C-NMR spectroscopy, optical rotation, and circular dichroism. The reaction gives stereoregular polymers as have other polymerizations and copolymerizations of this class.  相似文献   

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