Thermal stability of poly(vinyl bromide) and copolymers of vinyl bromide with methyl vinyl ketone

Thermal stability and degradation behaviour have been studied for PVB and VB-MVK copolymers spanning the whole composition range, using thermogravimetric analysis. The reactivity ratios in the radial copolymerization were determined by using an NMR technique, leading to r_i(VB) = 3.6 ± 0.2 and r₂(MVK) = 0.2 ± 0.1. The introduction of MVK units into the VB chain leads to an interaction with release of methyl bromide. The stability of the copolymers increases with increasing MVK concentration.     

Determination of the reactivity ratios of methyl acrylate with the vinyl acetate,vinyl 2,2-dimethyl-propanoate,and vinyl 2-ethylhexanoate

The course of composition drift in copolymerization reactions is determined by reactivity ratios of the contributing monomers. Since polymer properties are directly correlated with the resulting chemical composition distribution, reactivity ratios are of paramount importance. Furthermore, obtaining correct reactivity ratios is a prerequisite for good model predictions. For vinyl acetate (VAc), vinyl 2,2-dimethyl-propanoate also known as vinyl pivalate (VPV), and vinyl 2-ethylhexanoate (V2EH), the reactivity ratios with methyl acrylate (MA) have been determined by means of low conversion bulk polymerization. The mol fraction of MA in the resulting copolymer was determined by ¹H-NMR. Nonlinear optimization on the thus-obtained monomer feed–copolymer composition data resulted in the following sets of reactivity ratios: r_MA = 6.9 ± 1.4 and r_VAc = 0.013 ± 0.02; r_MA = 5.5 ± 1.2 and r_VPV = 0.017 ± 0.035; r_MA = 6.9 ± 2.7 and r_V2EH = 0.093 ± 0.23. As a result of the similar and overlapping reactivity data of the three methyl acrylate–vinyl ester monomer systems, for practical puposes these data can be described with one set of reactivity data. Nonlinear optimization of all monomer feed–copolymer composition data together resulted in r_MA = 6.1 ± 0.6 and r_VEst = 0.0087 ± 0.023. © 1994 John Wiley & Sons, Inc.     

Reactivity ratios and microstructure determination of vinyl acetate–alkyl acrylate copolymers by NMR spectroscopy

(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 r_v = 0.03 ± 0.03, r_E = 4.68 ± 1.70 (KT method); r_v = 0.03 ± 0.01, r_E = 4.60 ± 0.65 (EV method) for (V/E) copolymers and r_v ? 0.03 ± 0.01, r_B ? 6.67 ± 2.17 (KT method); r_v = 0.03 ± 0.01, r_B = 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.     

丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚合的研究

<正> 我们已经报道过甲基丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚合的研究。本文工作合成了丙烯酸甲酯与N-对卤苯基甲基丙烯酰胺共聚体,研究了这二组共聚体系的聚合反应、共聚体的组成、估算了单体的竞聚率,比较了这两种酰胺对丙烯酸甲酯与甲基丙烯酸甲酯的反应活性。     

Incorporation of POSS to improve thermal stability of bio-based polymethacrylates by nitroxide-mediated polymerization: Polymerization kinetics and characterization

Nitroxide-mediated polymerization (NMP) was used to polymerize methacrylate-functionalized polyhedral oligomeric silsesquioxane, POSSMA, in a controlled manner with bio-based C13 methacrylate (C13MA) to improve the thermal stability of the latter by copolymerization (using 10 mol% acrylonitrile controlling comonomer). Kinetic experiments (80–110 °C) revealed the relatively low ceiling temperature of POSSMA (135 °C). Synthesis of poly(POSSMA-co-AN) with f _AN,0 = 0.10 at 90 °C resulted in low dispersity (1.16) and relatively high conversion (~50%) after 3 hr in 50 wt% toluene. Assuming binary statistical copolymerizations, POSSMA was slightly less reactive than C13MA toward the propagating species (r _POSSMA = 0.91 ± 0.07 and r _C13MA = 1.94 ± 0.13). Incorporating POSSMA up to 68 mol% improved decomposition temperature of C13MA-based copolymers from 190 to 262 °C. Chain end fidelity of POSSMA-rich compositions was confirmed by subsequent chain extensions to make block and gradient copolymers. Differential scanning calorimetry revealed multiple transition temperatures in block copolymers, suggesting microphase separation. Powder X-ray diffraction confirmed crystalline domains ~30 nm in POSSMA-rich statistical copolymers while transmission electron microscopy revealed weakly ordered lamellar morphology for poly(C13MA-co-AN)-b-(POSSMA-co-AN) block copolymer at a smaller length scale. Oscillatory shear measurements of block copolymers indicated primarily viscous character below 200 s⁻¹ but crossover above this frequency, indicating POSS–POSS interactions were increasing the elasticity of the block copolymers.     

Alternating copolymers of hexafluoroisobutylene with vinyl trifluoroacetate and vinyl pentafluorobenzoate

Copolymerizations of hexafluoroisobutylene (HFIB) with vinyl pentafluorobenzoate (VPFB) and vinyl trifluoroacetate (VTFA) were carried out in bulk using perfluorodibenzoyl peroxide as the radical initiator. The copolymers obtained were characterized by proton and fluorine NMR spectroscopy. The monomer reactivity ratios in the polymerization of HFIB with VPFB were r₁ (HFIB) = 0, r₂ (VPFB) = 0.373, and r₁r₂ = 0. The results indicated that these copolymers have alternating structures. Similarly, the copolymers of HFIB and VTFA also showed alternating structures. The films of HFIB‐co‐VPFB were prepared by casting THF solution of polymers. Films obtained were flexible and transparent. The refractive indices of copolymers were 1.4549, 1.4490, and 1.4438 at 532, 633, and 839 nm, respectively. The average T_gs of HFIB‐co‐VTFA and HFIB‐co‐VPFB were 52 and 71 °C, respectively. From these results, the T_g of the hypothetical HFIB homopolymer is postulated to be in between 70 and 90 °C, which may be useful in the assessment of T_gs of HFIB copolymers with other vinyl monomers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Copolymerization and Copolymers of 2,4,5-Tribromostyrene with Methyl Acrylate and Methyl Methacrylate

Abstract

2,4,5-Tribromostyrene (TBSt) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in a toluene solution using 2,2′-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios were found to be for the system TBSt / MA r₁= 7.4 ± 1.2 (TBSt) and r₂= 0.1 ± 1.4 (MA) and for the system TBSt / MMA r₁ = 1.8 ± 0.2 (TBSt) and r₂ = 0.1 ± 0.2 (MMA). The e and Q values were also calculated. The initial rate of copolymerization, as well as molecular weight of the obtained copolymers for both system linearly increase as the content of TBSt in the monomer mixture increases. Similar behavior has also been established for the course of the copolymerization reactions to high conversions. The resulting copolymers rapidly decompose at temperatures 20–800°C above the decomposition of corresponding (metha)crylate hompolymers. However, the glass transition temperature increases markedly with increasing TBS content.     

Microstructure of glycidylmethacrylate/vinyl acetate copolymers by two‐dimensional nuclear magnetic resonance spectroscopy

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 r_G = 37.4 ± 12.0 and r_V = 0.036 ± 0.019 and r_G = 35.2 and r_V = 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     

Mn2(CO)10‐induced controlled/living radical copolymerization of vinyl acetate and methyl acrylate: Spontaneous formation of block copolymers consisting of gradient and homopolymer segments

The controlled/living radical polymerization of vinyl acetate (VAc) and its copolymerization with methyl acrylate (MA) were investigated in bulk or fluoroalcohols using manganese complex [Mn₂(CO)₁₀] in conjunction with an alkyl iodide (R? I) as an initiator under weak visible light. The manganese complex induced the controlled/living radical polymerization of VAc even in the fluoroalcohols without any loss of activity. The R? I/Mn₂(CO)₁₀ system was also effective for the copolymerization of MA and VAc, in which MA was consumed faster than VAc, and then the remaining VAc was continuously and quantitatively consumed after the complete consumption of MA. The ¹H and ¹³C NMR analyses revealed that the obtained products are block copolymers consisting of gradient MA/VAc segments, in which the VAc content gradually increases, and homopoly(VAc). The use of fluoroalcohols as solvents increased the copolymerization rate, controllability of the molecular weights, and copolymerizability of VAc. The saponification of the VAc units in poly(MA‐grad‐VAc)‐block‐poly(VAc) resulted in the corresponding poly(MA‐co‐γ‐lactone)‐block‐poly(vinyl alcohol) due to the intramolecular cyclization between the hydroxyl and neighboring carboxyl groups in the gradient segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1343–1353, 2009     

Kinetics of radical copolymerization of [1‐(fluoromethyl)vinyl]benzene with chlorotrifluoroethylene

The synthesis of [1‐(fluoromethyl)vinyl]benzene (or α‐(fluoromethyl)styrene, FMB) and its radical copolymerization with chlorotrifluorethylene (CTFE), initiated by tert‐butyl peroxypivalate (TBPPi) are presented. The allyl monomer [H₂C = C(CH₂F)C₆H₅] was obtained by electrophilic fluorodesilylation of trimethyl(2‐phenylprop‐2‐en‐1‐yl)silane in 93% yield. A series of seven copolymerization reactions were carried out starting from initial [CTFE]₀/([FMB]₀ + [CTFE]₀) molar ratios ranging from 19.6 to 90.0 mol %. The molar compositions of the obtained poly(CTFE‐co‐FMB) copolymers were assessed by means of ¹⁹F nuclear magnetic resonance spectroscopy. Statistic copolymers were produced with molar masses ranging between 13,800 and 25,600 g/mol. From the Kelen and Tudos method, the kinetics of the copolymerization led to the determination of the reactivity ratios, r_i, of both comonomers (r_CTFE = 0.4 ± 0.2 and r_FMB = 3.7 ± 1.8 at 74 °C) showing that FMB is more reactive than CTFE as well as other halogenated or nonhalogenated monomers involved in the radical copolymerization with CTFE. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3843–3850, 2007     

Homo- and copolymerization of N-(2-thiazolyl)methacrylamide with different vinyl monomers: Synthesis,characterization, determination of monomer reactivity ratios and biological activity

N-(2-thiazolyl)methacrylamide (TMA) monomer was synthesized from 2-aminothiazole by two different methods. The homo- and copolymerization of this monomer with methyl methacrylate (MMA), styrene (St), acrylonitrile (AN), and vinyl acetate (VA) were performed in dimethyl formamide using 1 mol% AIBN at 70°C. The copolymerization behavior was studied in a wide composition interval with the mole fractions of TMA ranging from 0.1 to 0.7 in the feed. Characterization using FTIR and 1HNMR techniques confirmed the structure of the monomer and the prepared homo- and copolymers, but the copolymers compositions were determined from sulphur analysis. The monomer reactivity ratios were computed using Fineman and Ross and Kelen and Tüdös methods for the systems TMA-MMA, TMA-St, TMA-AN and TMA-VA and were found to be r ₁ = 0.59 ± 0.05, r ₂ = 2.72 ± 0.03; r ₁ = 0.39 ± 0.02, r ₂ = 0.90 ± 0.01; r ₁ = 0.77 ± 0.06, r ₂ = 1.99 ± 0.04 and r ₁ = 0.80 ± 0.08, r ₂ = 0.40 ± 0.05 respectively (r ₁ corresponds to monomer reactivity ratio of TMA). The Q and e values for TMA monomer were found to be 1.079 and ?0.054. The synthesized monomer and polymers were tested in vitro for biological activity against some microorganisms, using the disk diffusion technique. Generally, all the polymers were effective against the tested microorganisms, but their growth-inhibition effects varied.     

Copolymerization of new pyrazolone-containing monomers with certain vinyl comonomers

The polymerization ability of two new pyrazolone-containing monomers—3-methyl-1-phenyl-4-crotonoyl-pyrazolone-5 ( Cr ) and 3-methyl-1-phenyl-4-(3′-phenyl-acryloyl) pyrazolone-5 ( Cy )—was investigated. The monomers were obtained by acylation of 3-methyl-1-phenyl-pyrazolone-5 with crotonyl chloride or cinnamoyl chloride, respectively. It was established that the two monomers do not homopolymerize either under the action of ionic and radical initiators nor with γ-rays (doses between 2 and 10 MRad). In contrast to this, the two monomers copolymerize with other vinyl comonomers. Copolymers of Cr and Cy with methacrylic acid (MAA), methyl methacrylate (MMA), and Styrene (St) were synthesized by radical copolymerization. The molecular weights of the polymer products obtained were in the 10,000–65,000 range. It was established that the molecular weight characteristics of the copolymers were affected by the concentration of the pyrazolone-containing monomer and by the chemical nature of the solvent used. The copolymerization of Cr and Cy with MAA was investigated in detail in order to evaluate the relative activity of the new monomers during copolymerization. The reactivity ratios (r) were calculated by three different methods with good agreement. The values obtained for the monomer pairs are: r_MAA = 0.61 ± 0.01, r_Cr = 0.04 ± 0.01; r_MAA = 0.64 ± 0.05, r_Cy = 0.02 ± 0.02. The Q/e values for Cr and Cy were determined using the reactivity ratios of both monomers.     

Copolymers of α-Methylstyrene with N-Cyclohexylacrylamide: Synthesis,Monomer Reactivity Ratios,and Mean Sequence Length

Abstract

Copolymerization of α-methylstyrene and N-cyclohexylacrylamide was carried out in toluene at 60 ± 1°C using azobisisobutyronitrile as the free-radical initiator. The total concentration of the comonomers was 1.5 mol·L^?1 in the solvent. The copolymers were characterized by ¹H-NMR and ¹³C-NMR spectroscopy, and the copolymer compositions were determined primarily from the ¹H-NMR spectra. The reactivity ratios were found to be r ₁ = 0.08 ± 0.01 and r ₂ = 2.45 ± 0.03 by the Fineman-Ross method, and r ₁ = 0.06 ± 0.01 and r ₂ = 2.43 ± 0.08 by the Kelen-Tüdös method. Mean sequence lengths in the copolymer were estimated from r ₁ and r ₂ values.     

Cationic copolymerization of β-pinene and epichlorohydrin

β-Pinene and epichlorohydrin (ECH) have been copolymerized cationically using BF₃(C₂H₅)₂O and SnCl₄ as catalysts. Polymerizations were carried out at ?80°C in methylenechloride. Monomer reactivity ratios were determined in both catalysts which were r₁(ECH) = 1.06 ± 0.15 and r₂ (β-pinene) = 0.32 ± 0.08 in BF₃(C₂H₅)₂O and r₁(ECH) = 0.33 ± 0.11 and r₂(β-pinene) = 2.03 ± 0.44 in SnCl₄. Copolymers of different composition were soluble in acetone and insoluble in methanol. This characteristic was taken to indicate that the polymeric products were real copolymers and not a mixture of two homopolymers of epichlorohydrin and β-pinene.     

Copolymerization parameters of acrolein and acidic vinyl monomers

Acrolein was copolymerized by radical initiation in aqueous solutions with sodium p-styrenesulfonate and acrylic acid, respectively, in the pH range of 3–7. The reactivities were shown to be pH-dependent. For the acrolein (M₁)–sodium p-styrenesulfonate (M₂) pair, r₁ = 0.33 ± 0.15 and r₂ = 0.32 ± 0.05 at pH 3; r₁ = 0.23 ± 0.12 and r₂ = 0.05 ± 0.03 at pH 5; r₁ = 0.26 ± 0.03 and r₂ = 0.025 ± 0.025 at pH 7. For the acrolein (M₁)–acrylic acid (M₂) pair, r₁ = 0.50 ± 0.30 and r₂ = 1.15 ± 0.2 at pH 3; r₁ = 2.40 ± 0.50 and r₂ = 0.05 ± 0.05 at pH 5; r₁ = 6.70 ± 3.00 and r₂ = 0.00 at pH 7. For acrolein, the new values of Q = 1.6 and e = 1.2 have been calculated. For sodium p-styrenesulfonate, the values Q = 0.76 and e = ?0.26 at pH 3, Q = 0.51 and e = ?0.87 at pH 5, Q = 0.39 and e = ?1.00 at pH 7 were obtained; and for acrylic acid, the values Q = 1.27 and e = 0.50 at pH 3, Q = 0.11 and e = ?0.22 at pH 5 were derived. The changes in reactivity are explained on the basis of inductive and resonance effects.     

Thermal stability of poly(acryloyl chloride) homopolymer and copolymers of acryloyl chloride with methyl methacrylate

The thermal stabilities of poly(acryloyl chloride) homopolymer and copolymers of acryloyl chloride with methyl methacrylate covering the entire composition range were studied by thermogravimetric analysis. At each extreme of the composition range incorporation of comonomer units results in a copolymer which is less stable than the PMMA homopolymer. The activation energies of the decomposition of the copolymers were calculated using the Arrhenius equation and found to decrease from 32.2 to 12.5 kJ mol^?1 as acryloyl chloride concentration of the copolymer increases, indicating that the copolymers of higher acryloyl chloride concentration should easier decompose than other copolymers. The reactivity ratios of the copolymer were calculated and found to ber ₁(AC)=0.2±0.02 andr ₂(MMA)=0.9±0.1.     

Alternating Copolymerization of Styrene and N-(4-Bromophenyl)Maleimide

Abstract

Free radical copolymerization of styrene (St) and N(4-bro-mophenyl)maleimide (4BPMI) in dioxane solution gave an alternating copolymer in all proportions of feed comonomer compositions. The monomer reactivity ratios were found to be r ₁, = 0.0218 ± 0.0064 (St) and r ₂, = 0.0232 ± 0.0112 (4BPMI), and the activation energy of the copolymerization reaction for the equimolar ratios of comonomer was E _a, = 51.1 kJ/mol. The molecular weights of the copolymers obtained are relatively high, the T _g's showed similar values (490 K), and the thermal stability is higher than that of polystyrene. The initial rate of copolymerization depends on the total concentration of the comonomers and the maximum occurred at higher 4BPMI mol fractions; however, the overall conversion is highest at equimolar comonomer composition. It has been shown that a charge-transfer complex participates in the process of copolymerization. The initial reaction rate was measured as a function of the monomer molar ratios, and the participation of the charge-transfer complex monomer and the free monomers was quantitatively estimated.     

Synthesis and characterization of styrenic polymers with pendant pyrazole groups. II

The synthesis of styrenic monomers that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with maleic anhydride (MA) and N-(3-acetoxy propyl) maleimide is reported. The monomers were prepared from the Williamson reaction between 2-pyridine carbinol, hydroxy monopyrazole, hydroxy bipyrazole, and chloromethyl styrene. The homopolymerizations of such styrenic monomers were tried under different conditions, which led to low molecular weight polymers with a high polydispersity. However, alternating copolymers were obtained using maleic anhydride or N-(3-acetoxy propyl) maleimide as comonomers, as shown by ¹H-NMR, elemental analysis, and reactivity ratios r₁ and r₂. Furthermore, the hydrolysis of the acetate function of different copolymers was performed quantitatively. Unlike the acetoxy copolymers, such products do not have any glass transition temperature. Thermogravimetric investigations have shown that these copolymers exhibit good thermostability. © 1994 John Wiley & Sons, Inc.     

SYNTHESIS AND THERMAL PROPERTIES OF A NEW CHOLIC ACIDCONTAINING COPOLYMER

A new copolymer was synthesized by free radical polymerization in solution from methyl 3α-methylacryloyl-7α, 12α-dihydroxy-5β-cholan-24-oate (MACAME) and maleic anhydride (MAN). The copolymer was characterized by FT-IR and functional group analysis. The reactivity ratios of the two monomers were estimated [r_1 = 11.6 (MACAME), r_2 = 0.01(MAN)] by conducting a series of copolymerizations with a variety of monomer feed compositions and analyzing thecopolymer composition. Thermogravimetric and differential scanning calorimetric analyses of the samples indicate that thecopolymer possesses good thermal stability. The temperature at which the copolymer samples experienced a 10% weight loss(T_(WL)) is over 287℃, and the T_g ranged from 174 to 185℃ for the copolymers.     

The structure of copolymers of vinyl cyclohexane with styrene

Copolymerization of vinyl cyclohexane (monomer-1) with styrene was investigated in the presence of the stereospecific complex catalyst TiCl₃ + Al(iso-C₄H₉)₃. Monomer reactivity ratios were r₁ = 0·177 ± 0·051 and r₂ = 2·117 ± 0·370. The monomer unit distributions in the copolymers were estimated by comparison of the i.r.-spectra of copolymers and the isotactic homopolymers using absorption bands at 565 and 1084 cm^?1 which correspond to the vibrations of styrene blocks containing ? 5 styrene units and the band at 985 cm^?1 characterizing polystyrene crystallinity. The data indicate the tendency towards alternation in the copolymerization. Analysis of the experimental and literature data led to the conclusion that distribution of the units in copolymers of vinyl cyclohexane with α-olefins is determined by the nature of the α-olefin. The following activity series is proposed for α-olefins in their copolymerization with vinyl cyclohexane in the presence of catalytic systems based on titanium salts and organo-aluminium compounds: propylene >; 4-methylpentene-1 >; styrene >; 3-methylbutene-1 ～ vinyl cyclohexane.