Reactivity Ratios and Sequence Distribution Characterization by Quantitative 13C NMR for RAFT Synthesis of Styrene‐Acrylonitrile Copolymers

The kinetics and reactivity ratios of styrene‐acrylonitrile (SA) copolymerization have been studied extensively in bulk and in a variety of solution media using conventional free radical polymerizations (FRPs). Due to the significant difference in the two reactivity ratios for this monomer pair, at certain feed ratios the copolymers display composition drift with conversion due to monomer depletion. In this study, the kinetics of SA copolymerization using Reversible Addition‐Fragmentation Chain Transfer (RAFT) has been studied in bulk at 80 °C. The reactivity ratios for the terminal model were calculated from the comonomer sequence distributions for the RAFT process at low conversion for nine different compositions and found to be in the same range as those reported for conventional FRP of SA. The changes in the composition and sequence distribution with conversion were studied for three feed compositions. The copolymers show compositional drift with conversion, except at the azeotropic composition, and match the predictions from the reactivity ratios obtained at low conversion. From quantitative ¹³C NMR the triad distributions of these copolymers were estimated and found to match the predicted triad distributions as conversion increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 919–927     

Cyclic Acetal-Photosensitized Polymerization. XII. Photopolymerizations of Styrene and Methyl Methacrylate in the Presence of Polycyclic Acetals

Styrene (St) and methyl methacrylate (MMA) were photopolymerized in the presence of poly-2-vinyl-1,3-dioxolane (PVDO), poly-2-vinyl-4-hydroxymethyl-1,3-dioxolane (PVHDO), or the terpolymer of vinyl formal/vinyl acetate/vinyl alcohol (PVFAcA) at 30 or 40°C. The ability to accelerate the photopolymerization increased in the order PVFAcA < PVHDO < PVDO; the ability of pendent cyclic acetal was larger than that of cyclic acetals which are not pendent. Moreover, the promoting ability per cyclic acetal increased with the increase in the number of cyclic acetal cyclic acetal group in the molecule.     

Copolymerization of 4‐Propanoylphenyl Acrylate with Methyl Methacrylate: Synthesis,Characterization and Reactivity Ratios

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 (M_w and M_n) 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.     

Copolymers of 3-Methoxy-4-Acryloyloxy-Benzal Phenylimine with Methyl Methacrylate: Synthesis,Characterization and Monomer Reactivity Ratios

Abstract

Copolymers of 3-methoxy-4-acryloyloxybenzal phenylimine and methyl methacrylate with different feed ratios are synthesized in ethyl methyl ketone using benzoyl peroxide as a free radical initiator at 70 ± 1°CC. The polymers were characterized by IR and ¹H-NMR spectroscopic techniques. Copolymer compositions were determined by ^lH-NMR analysis of the polymers. The monomer reactivity ratios were determined by the application of conventional linearization methods such as Fineman-Rose and Kelen-Tüdös. The molecular weights M_n and M_w of the polymers and the poly-dispersity index were determined by gel permeation chroma-tography. The intrinsic viscosities and the thermal properties of the homo-and copolymers are also discussed.     

Novel Photosensitive Polymer: Synthesis,Characterization and Thermal Properties of Polymer having Pendant Photocrosslinkable Group

New methacrylic monomer having free radical polymerizable methacryloyl group and photocrosslinkable functional group was synthesized by reacting hydroxyl chalcone with methacryloyl chloride. The monomer was homopolymerized in methyl ethyl ketone solvent using benzoyl peroxide as an initiator at 70°C. The prepared homopolymer was characterized by UV, FT‐IR, ¹H‐NMR and ¹³C‐NMR spectra. The molecular weights (M_w and M_n) were estimated by gel permeation chromatography. The thermal stability of the polymer was measured by thermogravimetric analysis. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The photocrosslinking property of the polymer was also studied.     

N-vinylpyrrolidone and 4-vinyl Benzylchloride Copolymers: Synthesis,Characterization and Reactivity Ratios

The copolymers prepared in this study by free radical copolymerization of N-vinylpyrrolidone (M ₂) with 4-vinylbenzylchloride (M ₁) using 2,2′-azobisisobutyronotrile (AIBN) initiator in 1,4-dioxane solvent at 70°C were characterized by FTIR, ¹H-NMR and ¹³C-NMR techniques. Polymer solubility was tested in both polar and nonpolar solvents. The thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). Copolymer compositions were established by H¹-NMR spectra, while reactivity ratios of the monomers were computed using the linearization methods viz., Fineman-Ross (FR) (r ₁ = 1.67 and r ₂ = 0.67), Kelen-Tudos (KT) (r ₁ = 1.77 and r ₂ = 0.65) and extended Kelen-Tudos (EK-T) (r ₁ = 1.72 and r ₂ = 0.63) methods at lower conversion. Furthermore, reactivity ratios in nonlinear error-in-variables method (RREVM) also compute the reactivity ratios (r ₁ = 1.76 and r ₂ = 0.66); these are found to be in good agreement with each other. The distribution of monomer sequence along the copolymer chain was calculated using a statistical method based on the calculated reactivity ratios.     

甲基丙烯酸缩水甘油酯与甲基丙烯酸甲酯的共聚合及竞聚率测定

以N,N-二甲基甲酰胺(DMF)为溶剂,实施了甲基丙烯酸缩水甘油酯(GMA)与甲基丙烯酸甲酯(MMA)的溶液共聚合,测定了共聚物P(GMA-co-MMA)的红外光谱(FT-IR),对其化学结构进行了表征,并采用差示扫描量热法(DSC)测定了共聚物的玻璃化转变温度(Tg).改变两单体投料比进行共聚合,采用化学分析法测定低转化率下(<7%)共聚物组成,重点研究了两单体的竞聚率.结果表明:GMA与MMA的共聚合易于进行,P(GMA-co-MMA)的玻璃化转变温度(Tg)介于均聚物PGMA(72℃)与PMMA(106℃)之间,当n(GMA)/n(MMA)=4/6时,共聚物的Tg为9l℃.采用FR和KT 2种作图法及YBR计算法对单体的竞聚率进行了计算和比较,结果表明:KT和YBR法较为准确,以DMF为溶剂时,GMA与MMA的竞聚率分别为2.14与0.69.     

New Methacrylate Copolymers Based on the Benzofurane Ring: Synthesis,Characterization, Monomer Reactivity Ratios and Biological Activity

The free radical copolymerization of (5-bromo-1-Benzofuran-2-yl)(phenyl)-O-methacrylketoxime (BPMKO) with 2-(4-acetylphenoxy)-2-oxoethyl-2-methylacrylate(AOEMA) has been carried out in 1, 4-dioxane at 65°C ± 1 and was analyzed by Fourier transform infrared, ¹H-NMR, ¹³C-NMR and gel permeation chromatography. Elemental analysis was used to determine the molar fractions of BPMKO and AOEMA in the copolymers. The monomer–reactivity ratios were calculated according to the general copolymerization equation using Kelen-Tüdõs and Finemann-Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers were determined by gel permeation chromatography and suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass-transition temperature of the copolymers increased with increasing BPMKO content in the copolymers. All the products showed moderate activity against different strains of bacteria and fungi.     

Copolymers Derived from Two Active Esters: Synthesis,Characterization, Thermal Properties,and Reactivity in Post-Modification

Copolymers with two distinguished reactive repeating units are of great interest, as such copolymers might open the possibility of obtaining selective and/or consequent copolymers with different chemical structures and properties. In the present work, copolymers based on two active esters (pentafluorophenyl methacrylate and p-nitrophenyl methacrylate) with varied compositions were synthesized by Cu(0)-mediated reversible deactivation radical polymerization. This polymerization technique allows the preparation of copolymers with high to quantitative conversion of both comonomers, with moderate control over dispersity (Đ = 1.3–1.7). Additionally, by in-depth study on the composition of each copolymer by various techniques including elemental analysis, NMR, FT-IR, and XPS, it was possible to confirm the coherence between expected and obtained composition. Thermal analyses by DSC and TGA were implemented to investigate the relation between copolymers’ composition and their thermal properties. Finally, an evaluation of the difference in reactivity of the two monomer moieties was confirmed by post-modification of copolymers with a primary amine and a primary alcohol as the model.     

Homopolymer and copolymers of 4-nitro-3-methylphenyl methacrylate with glycidyl methacrylate: Synthesis, characterization, monomer reactivity ratios and thermal properties

The novel methacrylic monomer, 4-nitro-3-methylphenyl methacrylate (NMPM) was synthesized by reacting 4-nitro-3-methylphenol dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine as a catalyst. The homopolymer and copolymers of NMPM with glycidyl methacrylate having different compositions were synthesized by free radical polymerization in EMK solution at 70 ± 1 °C using benzoyl peroxide as free radical initiator. The homopolymer and the copolymers were characterized by FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The solubility tests were tested in various polar and non-polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in NMPM content. The thermogravimetric analysis of the polymers performed in air showed that the thermal stability of the copolymer increases with NMPM content. The copolymer composition was determined using ¹H NMR spectra. The monomer reactivity ratios were determined by the application of conventional linearization methods such Fineman-Ross (r₁ = 1.862, r₂ = 0.881), Kelen-Tudos (r₁ = 1.712, r₂ = 0.893) and extended Kelen-Tudos methods (r₁ = 1.889, r₂ = 0.884).     

Copolymers of 4‐(3′,4′‐Dimethoxycinnamoyl)phenyl Acrylate and MMA: Synthesis,Characterization, Photocrosslinking Properties,and Monomer Reactivity Ratios

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.     

Synthesis and Characterization of a Series of Cationic Porphyrins Having Different Steric Effects

Abstract

A series of cationic porphyrins having only different steric effects and their cobalt complexes were synthesized. The cations of these porphyrins are meso-tetrakis(4-N-propylpyridyl)porphyrin (TPPyP⁴⁺), meso-tetrakis(4-N-ethylpyridyl)porphyrin (TEPyP⁴⁺) and meso-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP⁴⁺), respectively. The anions are I^? (water soluble porphyrins) and ClO₄ ^? (organic solvent soluble porphyrins), respectively. The synthetic cationic porphyrins were characterized by elemental analysis, UV-visible absorption spectra, FTIR, MALDI-TOF-MS and ¹H-NMR spectra.     

Statistical copolymers of methyl methacrylate and 2‐methacryloyloxyethyl ferrocenecarboxylate: Monomer reactivity ratios,thermal and electrochemical properties

Statistical copolymers of methyl methacrylate (MMA) with 2‐methacryloyloxyethyl ferrocenecarboxylate (MAEFC) were prepared by free radical polymerization. The reactivity ratios were estimated using the Fineman‐Ross, inverted Fineman‐Ross, Kelen‐Tüdos, and extended Kelen‐Tüdos graphical methods. Structural parameters of the copolymers were obtained by calculating the dyad monomer sequence fractions and the mean sequence length. The glass‐transition temperature (T_g) values of the copolymers were measured and examined by means of several theoretical equations, allowing the prediction of these T_g values. The thermal degradation behavior of the copolymers was also studied and compared with the respective homopolymers. Cyclic voltammetry was employed to study the electrochemical properties of the copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and Stereochemistry of New N-Substituted Cytisine Derivatives

A series of new N-substituted cytisine derivatives was synthesized. The ¹ H and ¹³ C NMR spectra of certain compounds exhibit a doubled set of signals. This is explained by formation of diastereomeric pairs in compounds containing an asymmetric center in the substituents. The signal splitting in -COHC=CHCO ₂ H and HC=O (formyl) derivatives is explained by the existence of Z and E invertomers. Their stereochemical features are discussed. Amide conjugation is confirmed by temperature experiments.     

Studies on photocrosslinkable copolymers of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone and methyl methacrylate

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.     

Copolymers of 7-Methoxy-2-Acetyl Benzofuryl Methylmethacrylate With Styrene: Synthesis,Characterization, Reactivity Ratios and Determination of Kinetic Parameters With Thermogravimetric Analysis

The 7-methoxy-2-acetyl benzofuryl methylmethacrylate (MABMM) monomer was synthesized by reacting 7-methoxy-2-bromo acetyl benzofurane with sodium methacrylate in acetonitrile solvent at 70°C in the presence of triethylbenzylammoniumchloride (TEBAC). The monomer was characterized by FTIR, ¹H-and ¹³C-NMR spectral studies. Reactivity ratios for the copolymers 7-methoxy-2-acetyl benzofuryl methylmethacrylate (MABMM)-co- styrene (ST) are reported. Copolymers were prepared by free radical polymerization using 2,2′-azobisisobutyronitrile (AIBN) as an initiator at 70°C in 1,4-dioxane solution. FTIR, ¹H-and ¹³C-NMR spectral studies and gel permeation chromatography (GPC) were used the copolymer characterization. The monomer compositions in the copolymer were determined by elementel analyses and the reactivity ratios (ri) were calculated applying diverse linear methods, namely Finemann-Ross (FR) and Kelen-Tüdös (KT) and the nonlinear error invariable model method of a computer program RREVM. By using the latter pr°Cedure, the values of the reactivity ratios were estimated as 2.74 and 0.69 for the system MABMM (1) and ST (2), respectively. These values suggest the formation of nearly-alternating copolymers in the systems. Molecular weights were determined by gel permeation chromatography (GPC). The polydispersity indices of the polymers determined using suggest a strong tendency for chain termination by disproportionation. The glass transition temperature of the polymers were investigated by Shimadzu DSC-60 and the apparent thermal decomposition activation energies (E_d) were calculated by the Ozawa method using the Perkin-Elmer TGA thermobalance, respectively. Tg increases when the concentration of polar monomer (MABMM) in the copolymer increases. It was observed that thermal stabilities of copolymers increased with increasing of MABMM content in copolymers.     

Synthesis and structure elucidation of three series of nitro‐2‐styrylchromones using 1D and 2D NMR spectroscopy

2‐Styrylchromones, although scarce in nature, constitute a group of oxygen heterocyclic compounds which have shown significant biological activities. New nitro‐2‐styrylchromones have been synthesised by the Baker–Venkataraman method, and the structure elucidation was accomplished using extensive 1D (1H, 13C) and 2D NMR spectroscopic studies (COSY, HSQC and HMBC experiments). Copyright © 2009 John Wiley & Sons, Ltd.     

Structural Assignment of Side Chain Liquid Crystalline Monomer and Polymer by 1-D and 2-D Solution NMR Studies

In the present study, the synthesis and characterization of a methacrylic-based side chain liquid crystalline monomer and its polymer were investigated with the aid of both 1-D and 2-D nuclear magnetic resonance (NMR) techniques. The mesophase characteristics of the monomer and polymer were determined by hot-stage optical polarized microscopy (HOPM). The nematic and smectic phases were observed for the monomer and polymer. Furthermore, ¹³C spin-lattice relaxation time measurements were performed on the above systems in order to monitor molecular dynamics. The present study provides an opportunity to carry out a systematic comparison of the evolution of structural as well as dynamical changes of the monomer and the polymer.     

Synthesis and Reactions of Some Novel Triazolo‐, Azolo‐, Tetrazolo‐Pyridopyrimidine and Their Nucleoside Derivatives

Pyridopyrimidine reacted with aromatic aldehydes afforded the arylhydrazone 2a,b which could be cyclized into the pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidine 3a,b , with formic acid, and carbon disulphide to give pyrido[2,3‐d][1,2,4]traizolo[4,3‐a]pyrimidine 4, 5. Reaction of 1 with nitrous acid afforded tetrazolo[1,5‐a]pyrido[2,3‐d]pyrimidine 6 , which was reduced by zinc dust to give 2‐amino‐pyrido‐[2,3‐d]pyrimidine 7. Finally the reaction of 2‐hydrazino 1 with D‐xylose or D‐glucose afforded the acyclic N‐nucleoside 8, 11 which were converted into tetra/penta O‐acetate acyclic C‐nucleoside 9, 12 in acetic anhydride/pyridine. De‐acetylation of compounds 9, 12 afforded C‐nucleosides 10, 13.     

Ambient Temperature Photocopolymerization of Tetrahydrofurfuryl Methacrylate and Isobornyl Methacrylate: Reactivity Ratios and Thermal Studies

Photocopolymerization of heterocyclic monomer namely, tetrahydrofurfuryl methacrylate with bulky bicyclic monomer, isobornyl methacrylate with different feed ratios was carried out in bulk with low concentration of an α-hydroxyl ketone based photoinitiator. The ambient temperature photocopolymerization was carried out by using a UV-Visible lamp with fixed low intensity of 0.4 mW cm^?2 for a period of 6 min. The residual monomer remained in the polymerization process were determined by using gas chromatography. The reactivity ratio values for the two monomers were calculated from the copolymer composition data by using Fineman-Ross, Kelen-Tudos, Extended Kelen-Tudos and Mao-Huglin methods. Individually, as well as the average of all the methods revealed that the monomer reactivity ratios of tetrahydrofurfuryl methacrylate were higher than isobornyl methacrylate. The dyad sequence distribution and dyad sequence lengths were calculated using the Igarashi and Pyun method and the sequence length distribution for tetrahydrofurfuryl methacrylate was observed to be higher with an increase in its feed content. This supports the reactivity ratio studies that a higher monomer reactivity ratio value for tetrahydrofurfuryl methacrylate was observed as compared to its comonomer. The thermal studies showed that the glass transition temperatures of the copolymers increased with an increase in isobornyl methacrylate content.