Synthesis,characterizations and thermal behavior of methyl methacrylate and N‐(p‐carboxyphenyl) methacrylamide/acrylamide copolymers

The synthesis, characterization, and thermal properties of copolymers of methyl methacrylate (MMA) and N‐(p‐carboxyphenyl) methacrylamide/acrylamide (CPMA/CPA) are described. The copolymerization was carried out in solution by taking different mole fractions (0.1–0.5) of CPMA/CPA in the initial feed using azobisisobutyronitrile as an initiator and dimethylformamide as a solvent at 60°C. The copolymer composition was determined from ¹H‐NMR spectra by taking the ratio of the proton resonance signal due to the  OCH₃ of MMA (δ = 3.59 ppm) and the aromatic protons (δ = 7.6–7.8 ppm) of CPMA/CPA. The monomer reactivity ratios of MMA:CPMA and MMA:CPA were determined using the Fineman Ross and Kelen Tudos methods and were found to be 1.32 ± 0.01 [MMA], 1.11 ± 0.02 [CPMA], 2.60 ± 0.01 [MMA], and 0.20 ± 0.01 [CPA]. Incorporation of these comonomers in the MMA backbone resulted in an improvement in the glass‐transition temperature and thermal stability. The percent char also increased with the increase of CPMA/CPA content in the copolymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 259–267, 2000     

Hyperbranched copolymers of p‐(chloromethyl)styrene and N‐cyclohexylmaleimide synthesized by atom transfer radical polymerization

The hyperbranched copolymers were obtained by the atom transfer radical copolymerization of p‐(chloromethyl)styrene (CMS) with N‐cyclohexylmaleimide (NCMI) catalyzed by CuCl/2,2′‐bipyridine (bpy) in cyclohexanone (C₆H₁₀O) or anisole (PhOCH₃) with CMS as the inimer. The influences of several factors, such as temperature, solvent, the concentration of CuCl and bpy, and monomer ratio, on the copolymerization were subsequently investigated. The apparent enthalpy of activation for the overall copolymerization was measured to be 37.2 kJ/mol. The fractional orders obtained in the copolymerization were approximately 0.843 and 0.447 for [CuCl]₀ and [bpy]₀, respectively. The monomer reactivity ratios were evaluated to be r_NCMI = 0.107 and r_CMS = 0.136. The glass transition temperature of the resultant hyperbranched copolymer increases with increasing f_NCMI, which indicates that the heat resistance of the copolymer has been improved by increasing NCMI. The prepared hyperbranched CMS/NCMI copolymers were used as macroinitiators for the solution polymerization of styrene to yield star‐shaped poly(CMS‐co‐NCMI)/polystyrene block copolymers by atom transfer radical polymerization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1992–1997, 2000     

Synthesis and characterization of N‐acryloylcarbazole/methyl methacrylate copolymers

Copolymers of N‐acryloylcarbazole (A) and methyl methacrylate (M) were synthesized in different in‐feed ratios. The composition of the copolymer was determined by the help of ¹H NMR spectrum. The comonomer reactivity ratios determined by Kelen‐Tudos (KT) and nonlinear error‐in‐variables methods were r_A = 1.12 ± 0.16, r_M = 0.94 ± 0.14, and r_A = 1.05, r_M = 0.90, respectively. Complete spectral assignments of the ¹H and ¹³C ¹H NMR spectra of the copolymers were done by the help of distortionless enhancement by polarization transfer (DEPT) and two‐dimensional NMR techniques, such as heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple bond correlation (HMBC). The methine, α‐methyl, and carbonyl carbon resonances were found to be sequence sensitive. The signals obtained were broad because of the restricted rotation of bulky carbazole group and the quadrupolar effect of nitrogen present in carbazole moiety. Glass transition temperatures (T_g) were determined by differential scanning calorimetry and were found to be characteristic of copolymer composition. As the N‐acryloylcarbazole content increases, the T_g increases from 378.3 K for poly(methyl methacrylate) to 430.4 K for poly(N‐acryloylcarbazole). Variation in T_g with the copolymer composition were found to be in good agreement with theoretical values obtained from Johnston and Barton equations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2667–2676, 2006     

Morphology and thermal properties of liquid crystal p‐PAEB/n‐propyl methacrylate copolymers

The copolymers of p‐phenylene di{4‐[2‐(allyloxy) ethoxy]benzoate} (p‐PAEB) with n‐propyl methacrylate (PMA) were synthesized. The liquid crystalline behavior and thermal properties of copolymers were studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), X‐ray diffractometer (XRD), and torsional braid analysis (TBA). The results of XRD, POM, and DSC demonstrate that the phase texture of copolymers is affected by the composition of liquid crystal units in copolymers. The POM and XRD reveal that liquid crystal monomer (p‐PAEB) and copolymers of p‐PAEB with PMA are all smectic phase texture. The dynamic mechanical properties of copolymers are investigated with TBA. The results indicate that the phase transition temperatures and dynamic mechanical loss peak temperature T_p of copolymers are affected by the composition of copolymers and liquid crystal cross networks. The maximal mechanical loss T_p is 114°C and is decreased with added PMA. The behaviors of phase transition are affected by the crosslinking density, and it is revisable for lightly crosslinking LC polymer networks, but it is nonreversible for the densely crosslinking of LC polymer networks. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Photophysical studies of copolymers of N‐vinylcarbazole

The absorption, fluorescence excitation and emission spectroscopy, and time‐dependent spectrofluorimetry have been used to study the photophysics of copolymers of N‐vinylcarbazole with different monomers like vinyl acetate, methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate in dichloromethane. In all the copolymers and at different N‐vinylcarbazole content, the absorption spectra reflect only the monomer carbazole units. The two kinds of excited monomer species of N‐vinylcarbazole are present in S₁ state. Short‐lived (～3 ns) excited monomer decays forming low energy excimer obtained by the complete overlap of the excited carbazole monomer. The long‐lived excited monomer (～8 ns) decays to ground state without formation of any excimer. The high energy excimer is relatively short‐lived and is formed by the partial overlap of the carbazole units. The presence of bulky group in the copolymer chain hinders the formation of excimers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 372–380, 2006     

Bioengineering functional copolymers: V. Synthesis,LCST, and thermal behavior of poly(N‐isopropyl acrylamide‐co‐p‐vinylphenylboronic acid)

New boron‐containing stimuli‐responsive (pH‐ and temperature‐sensitive) copolymers were synthesized and characterized. Structure and composition of copolymers were determined by FTIR and ¹H‐NMR spectroscopy, and elemental analysis and titration (N and B contents for NIPA and VPBA unit, respectively). By DSC and XRD measurements, it is established that the synthesized copolymers have a semicrystalline structure due to formation of intra‐ and/or intermolecular H‐bonded supramolecular architecture. The copolymer composition–structure–property relationship indicates semicrystalline structure of copolymers with different compositions, degrees of crystallinity, and thermal and stimuli‐responsive behaviors depends on the content of boron‐containing monomer linkage. Results of DSC, DTA, and TGA analyses indicated that copolymers have T_g and T_m and high thermal stability. These water‐soluble and temperature‐ and pH‐sensitive amphiphilic copolymers can be used as polymeric carries for delivery of biological entities for diverse biomedical use, including boron neutron capture therapy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 573–582, 2005     

Nuclear magnetic resonance studies of N‐vinylcarbazole/methyl methacrylate copolymers

Copolymers of N‐vinylcarbazole and methyl methacrylate of different compositions were prepared by solution polymerization with azobisisobutyronitrile as an initiator, and their compositions were determined from quantitative ¹³C{¹H}‐NMR spectroscopy. The reactivity ratios for the comonomers were calculated with the Kelen–Tudos and nonlinear error‐in‐variable methods. The complete spectral assignment of the overlapping ¹H and ¹³C{¹H} spectra of the copolymers was made with the help of distortionless enhancement by polarization transfer, two‐dimensional heteronuclear single‐quantum correlation, and total correlation spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3005–3012, 2003     

Studies on the copolymerization of methyl methacrylate with N‐(o/m/p‐chlorophenyl) itaconimides

The article describes the synthesis and characterization of N‐aryl itaconimide monomers such as: N‐(p‐chlorophenyl) itaconimide (PI)/N‐(m‐chlorophenyl) itaconimide (MI)/N‐(o‐chlorophenyl) itaconimide (OI) and its copolymerization behavior with MMA. The homopolymers and copolymers of N‐aryl itaconimides and methyl methacrylate (MMA, M₂) were synthesized by varying the mol fraction of N‐aryl itaconimides in the initial feed from 0.1 to 0.5 using azobisisobutyronitrile (AIBN) as an initiator and tetrahydrofuran (THF) as the solvent. Copolymer composition was determined using ¹H‐NMR spectroscopy [by taking the ratio of intensities of signals due to ? OCH₃ of MMA (δ = 3.59 ppm) and the aromatic proton (δ = 7.2–7.5 ppm) of N‐aryl itaconimides] and percent nitrogen content. The reactivity ratios were found to be r₁ = 1.33 and r₂ = 0.36 (PI‐MMA) r₁ = 1.15 and r₂ = 0.32 (MI‐MMA) and r₁ = 0.81 and r₂ = 0.35 (OI‐MMA). Molecular weight as determined using high‐performance liquid chromatography decreased with increasing mol fraction of itaconimides in copolymers. All the polymers had a polydisperstivity index in the range of 1.5–2.6.Thermal characterization was done using differential scanning calorimetry and dynamic thermogravimetry in nitrogen atmosphere. Incorporation of these N‐aryl itaconimides in PMMA backbone resulted in an improvement in glass transition temperature (T_g) and thermal stability. Percent char increased with the increase of PI/MI/OI content in the copolymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2078–2086, 2001     

Spectroelectrochemical study of N‐ethyl‐carbazole in the presence of acrylamide

Polymerization of N‐ethylcarbazole (NECz) in the presence of acrylamide (AAm) has been investigated by in situ and ex situ UV–visible spectrophotometric measurements to obtain information about the reaction pathway, because NECz gives soluble oligomeric species allowing such measurements. A tentative mechanism is proposed in the light of these results. The redox properties of the new polymers have been studied for possible sensor application. © 2001 Society of Chemical Industry     

Poly(N‐isopropylacrylamide‐co‐sodium acrylate) hydrogels: Interactions with surfactants

Poly(N‐isopropylacrylamide‐co‐sodium acrylate) [poly(NIPAM‐co‐SA)] hydrogels were modified with three different kind of surfactants (cationic, anionic, and nonionic) to study the effect on the swelling properties. The structural variation of the surfactant‐modified hydrogels was investigated in detail. The interaction between the surfactants and the hydrogel varies and strictly depends on the surfactant type. The variation in thermal stability of the modified surfactant hydrogels was investigated and compared with unmodified hydrogel. Further, the hydrogel swelling/diffusion kinetic parameters were investigated and diffusion of water into hydrogel was found to be of the non‐Fickian transport mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3423–3430, 2007     

Stabilization of vinyl chloride/vinylidene chloride copolymers using N‐substituted maleimides

As a consequence of their excellent barrier properties, vinyl chloride/vinylidene chloride copolymers have long been prominent in the flexible packaging market. While these polymers possess a number of superior characteristics, they tend to undergo thermally induced degradative dehydrochlorination at process temperatures. This degradation must be controlled to permit processing of the polymers. Three series of N‐substituted maleimides (N‐alkyl‐, N‐aralkyl‐, and N‐aryl‐) have been synthesized, characterized spectroscopically, and evaluated as potential stabilizers for a standard vinyl chloride/vinylidene chloride (85 wt%) copolymer. As surface blends with the polymer, these compounds are ineffective as stabilizers. However, significant stabilization may be achieved by pretreatment of the polymer with N‐substituted maleimides. The most effective stabilization of the polymer is afforded by N‐aralkyl‐ or N‐arylmaleimides, most notably, N‐benzylmaleimide and N‐(p‐methoxyphenyl)maleimide. J. VINYL. ADDIT. TECHNOL. 12:88–97, 2006. © 2006 Society of Plastics Engineers.     

New crosslinked N‐vinylpyrrolidone copolymers: Synthesis and sorptive properties

The crosslinked copolymers of N‐vinylpyrrolidone with 1,4‐(N,N′‐bismaleimido)benzol and with trimethoxyvinylsilane were synthesized by free radical copolymerization. The copolymers were characterized by FTIR spectroscopy and thermal analysis. The values of specific surface area and porosity of the copolymers were determined with use of low‐temperature adsorption. Sorption capacity of the copolymers toward Re (VII), Mo (VI), and W(VI) ions was investigated and was found to depend strongly on the pH. A possibility to separate Re(VII) and Mo(VI) ions with use of the copolymers under investigation in their combined presence in neutral and alkaline media was shown. Moreover, in the conjoined presence of Mo(VI) and W(VI) ions at pH 5–14, tungsten(VI) can be separated from molybdenum(VI) with the copolymer of N‐vinylpyrrolidone with trimethoxyvinylsilane. POLYM. ENG. SCI., 56:1303–1312, 2016. © 2016 Society of Plastics Engineers     

Investigation of microstructure of the N‐vinyl‐2‐pyrrolidone/methyl methacrylate copolymers by NMR spectroscopy

The copolymers containing N‐vinyl‐2‐pyrrolidone (V) and methyl methacrylate (M) units of different compositions were synthesized by free radical bulk polymerization. The copolymer composition of these copolymers was determined by CHN analysis. The distortionless enhancement by polarization transfer (DEPT) technique was used to resolve the methine, methylene, and methyl resonance signals in the V/M copolymer. Comonomer reactivity ratios were determined by the Kelen–Tudos (KT) and nonlinear least‐square error‐in‐variable (EVM) methods. ¹H–¹³C Heteronuclear shift quantum correlation spectroscopy (HSQC) and ¹H–¹H homonuclear total correlation spectroscopy (TOCSY) spectra were used for the resolution of the proton nuclear magnetic resonance (¹H NMR) spectrum of the V/M copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1328–1336, 2002     

Radical polymerization of methyl methacrylate in the presence of N,N‐dimethyl‐N‐(methylferrocenyl)amine

The specific features of free‐radical polymerization of methyl methacrylate in the presence of a new initiating system, benzoyl peroxide‐N,N‐dimethyl‐N‐(methylferrocenyl)amine, are studied. Mutual influence of ferrocenyl‐ and amine groups on kinetic parameters of polymerization and on the microstructure of the resulting polymers is found. It is shown that the polymer obtained in the presence of this initiating system has predominantly syndiotactic structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 724–727, 2007     

Microstructure analysis of N‐vinyl‐2‐pyrrolidone/vinyl acetate copolymers by NMR spectroscopy

N‐Vinyl‐2‐pyrrolidone (V) and vinyl acetate (A) copolymers of different compositions were synthesized by free radical bulk polymerization. The copolymer composition of these copolymers was determined using quantitative ¹³C{¹H} NMR spectra. The reactivity ratios for these comonomers were determined using the Kelen–Tudos (KT) and non‐linear least‐square error‐in‐variable (EVM) methods. The reactivity ratios calculated from the KT and EVM methods are r_V = 2.86 ± 0.16, r_A = 0.36 ± 0.09 and r_V = 2.56, r_A = 0.33, respectively. ¹H, ¹³C{¹H} and ¹H–¹³C heteronuclear shift correlation spectroscopy (HSQC) and ¹H–¹H homonuclear total correlation spectroscopy (TOCSY) were used for the compositional and configurational assignments of V/A copolymers. The ¹³C distortionless enhancement by polarization transfer (DEPT) technique was used to resolve the methine, methylene and methyl resonance signals in the V/A copolymers. © 2002 Society of Chemical Industry     

Copolymerization and thermal behavior of methyl methacrylate with N‐(phenyl/p‐tolyl) itaconimides

This study describes the synthesis, characterization, and thermal behavior of copolymers of methyl methacrylate (MMA) and N‐p‐tolyl itaconimide (PTI)/N‐phenyl itaconimide (I). Homopolymerization and copolymerization of N‐(phenyl/p‐tolyl) itaconimide with MMA was carried out by use of various mole fractions of N‐aryl itaconimide in the initial feed from 0.1 to 0.5, using azobisisobutyronitrile as an initiator and tetrahydrofuran as the solvent. The copolymer composition was determined by ¹H‐NMR spectroscopy using the proton resonance signals attributed to –OCH₃ of MMA (δ = 3.5–3.8 ppm) and the aromatic protons (δ = 7.0–7.5 ppm) of N‐aryl itaconimide. The reactivity ratios of the monomers were found to be r₁ (PTI) = 1.33 ± 0.05/r₂ (MMA) = 0.24 ± 0.03 and r₁ (I) = 1.465 ± 0.035/r₂ (MMA) = 0.385 ± 0.005. The molecular weight of the copolymers decreased with increasing mole fraction of N‐aryl itaconimide in the copolymers. Glass‐transition temperature (T_g) and thermal stability of PMMA increased with increasing amounts of itaconimides in the polymer backbone. A significant increase in the percentage char yield at 700°C was observed on incorporation of a low mole fraction of N‐aryl itaconimides. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1195–1202, 2003     

A New Strategy for the Preparation of Terephthalic Acid by the Aerobic Oxidation of p‐Xylene using N‐Hydroxyphthalimide as a Catalyst

A new methodology for the production of terephthalic acid ( 3 ) by the aerobic oxidation of p‐xylene ( 1 ) using a combined catalytic system of N‐hydroxyphthalimide (NHPI)/Co(OAc) ₂/Mn(OAc) ₂was developed. The oxidation of 1 under a dioxygen atmosphere in the presence of a catalytic amount of NHPI/NHPI(OAc) ₂/Mn(OAc) ₂at 100 °C for 14 h afforded terephthalic acid in 82% yield. Removal of Mn(OAc) ₂ from the catalytic system resulted in considerable reduction in the yield of 3 . When the oxidation of 1 was carried out under a pressure of air (30 atm) at 150 °C, the reaction was completed within 3 h to give 3 in 84% yield. The oxidation of p‐toluic acid ( 2 ), which can be prepared by the oxidation of 1 using the NHPI/NHPI(OAc) ₂ system at room temperature, by the NHPI/NHPI(OAc) ₂/Mn(OAc) ₂system under pressure of air (30 atm) at 150 °C gave 3 in 95% yield. N‐Acetoxyphthalimide (NAPI) was found to require a lower catalyst loading than NHPI, but oxidation with NAPI was slower. Thus, the oxidation of 1 catalyzed by NAPI (5 mol %)/Co(OAc) ₂ (0.5 mol %)/Mn(OAc) ₂ (0.5 mol %) under a dioxygen atmosphere (1 atm) in acetic acid at 100 °C gave 3 in 80% yield.