Effect of chlorosilanes on the radical polymerization of styrene and methyl methacrylate

Styrene (St) and methyl methacrylate (MMA) were polymerized by azobisisobutyronitrile at 50°C. in the presence of silanes such as tetramethylsilane, trimethylcholorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane. The polymerization rates of both St and MMA in the presence of silanes were nearly equal to those in the absence of silanes. On the other hand, the molecular weights decreased gradually as the concentration of chlorosilane increased. The chain transfer constants of all the silanes in the polymerization of St and MMA at 50°C. were calculated by Mayo's equation. The chain transfer constants of Me₄Si, Me₃SiCl, Me₂SiCl, MeSiCl₃, and SiCl₄ were 0.31 × 10^?3, 1.25 × 10^?3, 1.78 × 10^?3, 1.92 × 10^?3, and 2.0 × 10^?3, for St and 0.13 × 10^?3, 0.22 × 10^?3, 0.245 × 10^?3, 0.27 × 10^?3, and 0.30 × 10^?3, for MMA, respectively. From these results, it was found that the Si? Cl bond was radically cleaved. The Q_tr values of the silanes, in the same order as above, were found to be 1.03 × 10^?4, 2.33 × 10^?4, 2.83 × 10^?4, 3.10 × 10^?4, and 3.35 × 10^?4, respectively and the e_tr values were +0.58, +1.30, +1.50, +1.48, and +1.43, respectively.     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.     

p-ACETYLBENZYLIDENE TRIPHENYLARSONIUM YLIDE (p-ABTAY) INITIATED RADICAL COPOLYMERIZATION OF METHYLMETHACRYLATE WITH STYRENE

p-Acetylbenzylidene triphenylarsonium ylide (p-ABTAY) initiated radical copolymerization of methylmethacrylate (MMA) with styrene in dioxane, at 60 ± 0.1°C, under the inert atmosphere of nitrogen yields alternating copolymer, as evidenced by ¹H NMR spectroscopy. The kinetic equation for the present system is Rp μ[p-ABTAY]^0.46 [MMA] [Sty]. The rate of copolymerization (Rp) is proportional to the square root of [p-ABTAY] indicating bimolecular termination. The values of kp²/kt and energy of activation have been computed as 6.3 × 10^?3 l mol^?1s^?1 and 63 KJ mol l^?1, respectively. The reactivity ratios have been calculated as r₁ (MMA) = .60, r₂ (Sty) = .35, by using the Kelen-Tudös method. The copolymerization reaction is initiated by the phenyl free radical. The formation of phenyl radicals may be attributed to the pp-dp overlap between the hybridized sp² orbital and the larger and more diffuse 4d orbital of arsenic.     

Preparation of soluble microgel by the copolymerization of methylmethacrylate with p-divinylbenzene in the presence of tetrabromomethane

Various types of soluble crosslinked polymers obtained from the copolymerization of methylmethacrylate (MMA) and p-divinylbenzene (p-DVB) in the presence of a transfer agent (CBr₄) have been discussed in relation to the variation of the structure during the reaction time. When [p-DVB]/[MMA] = 1.49 × 10^?3 and [CBr₄]/[MMA] = 1.28 × 10^?4, only linear polymers (primary polymer; M _n = 1.0 × 10⁵) with pendant vinyl groups are formed intially. Considerable branched structure is attained in rather large polymers (M _n = 2.5 × 10⁵), but the number of pendant double bonds is not enough to reach the gelation. As the concentration of the transfer agent becomes high, the intermolecular crosslinking is depressed, and the formed polymers contain loops and short chains. At [p – DVB]/[MMA] = 7.43 × 10^?3 and [CBr₄]/[MMA] = 1.28 × 10^?3, the shape of polymer with the same M _n became compact gradually with increasing reaction time. These results are considered to be useful for the preparation of soluble crosslinked polymer with controlled structure.     

Polymerization of methyl methacrylate by a charge transfer mechanism with urea and iron (III) complex

Methyl methacrylate (MMA) can be polymerized by a charge transfer complex formed by the interaction of urea, methyl methacrylate, and carbon tetrachloride (CCl₄) in a nonaqueous solvent like dimethylsulfoxide (DMSO). The rate of polymerization can be accelerated by Lewis acids like Fe³⁺. This article reports the polymerization of MMA initiated by urea and CCl₄ and accelerated with hexakisdimethylsulfoxide iron (III) perchlorate, [Fe(DMSO)₆](ClO₄)₃, and A at 60°C. Definite induction periods were observed for the polymerization reaction initiated by urea and CCl₄ alone, but the induction period completely vanished when the molar ratio of urea to A reached 6:1. The molecular weights of the polymers with 6:1 molar ratio of urea to A were higher than with urea alone. The rate constant for the polymerization of MMA in the presence of [Fe(urea)₆]³⁺ was 1.03 × 10^?5 1 mol^?1 s^?1 at 60°C. The transfer constant for CCl₄ for polymerization with urea alone is 2.43 × 10^?3 at 60°C.     

Ascorbic Acid/H2O2-initiated Graft Copolymerization of Methyl Methacrylate onto Abelmoschus Esculentus Fiber: A Kinetic Approach

Graft copolymerization of methyl methacrylate onto lignocellulosic Abelmoschus esculentus fibers was successfully carried out in aqueous medium using ascorbic acid and hydrogen peroxide as redox initiator. Maximum percentage of grafting was achieved when the concentrations of ascorbic acid, hydrogen peroxide, and monomer were 3.85 × 10^?2, 2.41 × 10^?1, and 1.87 × 10^?1 mol/L respectively at a temperature of 45°C for a reaction time of 90 min. The kinetics of graft copolymerization was also studied, and it was found that the rate expression for graft copolymerization is (R_g) = K [Asc]^0.68[H₂O₂]^0.49[MMA]^1.17. The activation energy for graft copolymerization of MMA onto Abelmoschus fiber was found to be 12.48 KJ/mol. The graft copolymers thus formed were characterized by FT-IR spectroscopy, scanning electron microscopy and thermogravimetric analysis.     

Polymerization of methyl methacrylate by charge transfer mechanism by melamine and iron(III) complex

Methyl methacrylate (MMA) can be polymerized by the charge-transfer complex formed by the interaction of melamine (MM), MMA and carbon tetrachloride in a non-aqueous solvent like dimethyl sulphoxide (DMSO) or N-N-dimethylformamide. The polymerization can be accelerated by Lewis acids like Fe^3?. This paper reports the polymerization of MMA initiated by MM and CCl₄ and accelerated with hexakis dimethylsulphoxide iron(III) perchlorate [Fe(DMSO)₆] (ClO₄)₃. A, at 60°. Induction periods were observed for the polymerization initiated by MM and CCl₄ alone, but not when the molar ratio of MM to A became 3:1. The molecular weights of the polymers with 3:1 molar ratio of MM to A were higher than with MM alone. The rate constant for the polymerization of MMA in presence of [Fe(MM)₃]³⁺ was 1.4181 × 10^?5 1 mol^?1 sec^?1 at 60°. The transfer constant for CCl₄, in the absence of A, is 4.66 × 10^?3.     

Controlled synthesis of polyepichlorohydrin with pendant cyclic carbonate functions for isocyanate‐free polyurethane networks

Poly(allyl glycidyl ether) and poly(allyl glycidyl ether‐co‐epichlorohydrin) were prepared by monomer‐activated anionic polymerization. Quantitative and controlled polymerization of allyl glycidyl ether (AGE) giving high molar mass polyether was achieved in a few hours at room temperature in toluene using tetraoctylammonium salt as initiator in presence of an excess of triisobutylaluminum ([i‐Bu₃Al]/[NOct₄Br] = 2?4). Following the same polymerization route, the copolymerization of AGE and epichlorohydrin yields in a living‐like manner gradient‐type copolymers with controlled molar masses. Chemical modification of the pendant allyl group into cyclic carbonate was then investigated and the corresponding polymers were used as precursors for the isocyanate‐free synthesis of polyurethane networks in presence of a diamine. Formation of crosslinked materials was followed and characterized by infrared and differential scanning calorimetry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of epoxy functionalized cooligomers based on chlorotrifluoroethylene and allyl glycidyl ether

The synthesis of functionalized fluorocooligomers based on chlorotrifluoroethylene (CTFE) and allyl glycidyl ether (AGE) under radical copolymerization is presented. The compositions of comonomers in the cooligomers were determined by three different analyses viz: from ¹H and ¹⁹F NMR spectroscopy by using 1,3‐bis(trifluoromethyl) benzene as the external standard, epoxy equivalent weight value, and elemental analyses. The compositions determined by three methods were matching reasonably well and showed that the resulting poly(CTFE‐co‐AGE) cooligomers exhibit a tendency for alternation. The distribution of the monomers in the cooligomers was proposed based on the assessment of the reactivity ratios, r_i, of both comonomers. These values were determined from the kinetics of radical copolymerization of CTFE with AGE from Fineman‐Ross, Kelen‐Tudos, and extended Kelen‐Tudos methods which led to the assessment of the average reactivity ratios as: r_CTFE = 0.20 ± 0.03 and r_AGE = 0.15 ± 0.08 at 74 °C. The lower M_n values substantiated the formation of cooligomers rather than copolymers. The formation of cooligomers was attributed to the chain transfer to AGE (by hydrogen abstraction from AGE) from the allylic transfer. The poly(CTFE‐co‐AGE) cooligomers were soluble in most of the common organic polar solvents. An optimization of cooligomer yields was investigated by using ethyl vinyl ether as a third comonomer and from different initiators. The thermal stabilities of the cooligomers, obtained by thermal gravimetric analysis, showed a 5% weight loss at temperatures over 225 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3587–3595, 2010     

Kinetic and ESR studies on radical polymerization of methyl methacrylate in the presence of fullerene

The effect of fullerene (C₆₀) on the radical polymerization of methyl methacrylate (MMA) in benzene was studied kinetically and by means of ESR, where dimethyl 2,2′-azobis(isobutyrate) (MAIB) was used as initiator. The polymerization rate (R_p) and the molecular weight of resulting poly(MMA) decreased with increasing C₆₀ concentration ((0–2.11) × 10⁻⁴ mol/L). The molecular weight of polymer tended to increase with time at higher C₆₀ concentrations. R_p at 50°C in the presence of C₆₀ (7.0 × 10⁻⁵ mol/L) was expressed by R_p = k[MAIB]^0.5[MMA]^1.25. The overall activation energy of polymerization at 7.0 × 10⁻⁵ mol/L of C₆₀ concentration was calculated to be 23.2 kcal/mol. Persistent fullerene radicals were observed by ESR in the polymerization system. The concentration of fullerene radicals was found to increase linearly with time and then be saturated. The rate of fullerene radical formation increased with MAIB concentration. Thermal polymerization of styrene (St) in the presence of resulting poly(MMA) seemed to yield a starlike copolymer carrying poly(MMA) and poly(St) arms. The results (r₁ = 0.53, r₂ = 0.56) of copolymerization of MMA and St with MAIB at 60°C in the presence of C₆₀ (7.15 × 10⁻⁵ mol/L) were similar to those (r₁ = 0.46, r₂ = 0.52) in the absence of C₆₀. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2905–2912, 1998     

Studies on the kinetics of polymerization of vinyl acetate by benzoyl peroxide at 60° using pyridine as solvent

Kinetics of Bz₂O₂-initiated polymerization of VAC in pyridine at 60° were investigated. The polymerization was significantly retarded by pyridine. The monomer exponent decreased from 2.5 at a relatively low [Bz₂O₂] (1.0 × 10^?2 M) to 2.0 at [Bz₂O₂] ? 4.0 × 10^?2 M. The observed kinetic features were explained on the basis of degradative chain transfer and copolymerization with pyridine.     

Synthesis and Modification of Functional Polycarbonates with Pendant Allyl Groups

Functional aliphatic polycarbonates with pendant allyl groups were synthesised by copolymerization of carbon dioxide and allyl glycidyl ether (AGE) in the presence of a catalyst system based on ZnEt₂ and pyrogallol at a molar ratio 2 : 1. The functionality of some polycarbonates was reduced by replacing a part of allyl ether with saturated glycidyl ether, i.e., butyl glycidyl ether (BGE) or isopropyl glycidyl ether (IGE). Polycarbonates obtained by the copolymerization of AGE and CO₂ or by the terpolymerization of AGE, IGE and CO₂ were oxidized with m‐chloroperbenzoic acid to their respective poly(epoxycarbonate)s. The influence of the AGE/ΣGE ratio in the polycarbonates, the polymer concentration in the reaction solution and the duration of the reaction on the conversion of allyl groups into glycidyl ones was examined. A tendency to gelation of the initial and oxidized polycarbonates during storage was observed. The initial polycarbonates and their oxidized forms were degraded in aqueous buffer of pH = 7.4 at 37°C. The course of hydrolytic degradation was monitored by the determination of mass loss.     

Radiation polymerization of methacrylates controlled by a chain transfer catalyst

The effect of γ-radiation dose and chain transfer catalyst on polymerization of methyl methacrylate (MMA) and copolymerization of MMA with hydroxyethyl methacrylate or triethylene glycol dimethacrylate has been investigated. The addition of 5 × 10^?4?10^?3 mol/L of bis[(difluoroboryl) isopropylpyridine dimethylglyoximato]cobalt(II) (Co(II)) makes it possible to produce macromonomers MM _n ⁼⁼ bearing terminal double bonds and having a degree polymerization of n = 2?40 and a polydispersity index of 1.05?1.15. It has been found that the degree polymerization of the macromonomers increases with the increasing γ-radiation dose and monomer conversion through the mechanism of the reversible β-cleavage of the terminal unit: R _k ^? + MM _n ⁼ ? MM _k+1 ⁼ + R _n-1 ^? followed by the living polymerization of both radicals. This reaction may compete with the catalytic chain transfer reaction and have a significant effect on the evolution of the molecular weight characteristics of the macromonomers during the course of MMA (co)polymerization.     

Ethylene propylene diene terpolymers produced with a homogeneous and highly active zirconium catalyst

EPDM terpolymers with ethylidene norbornene as diene monomer could be prepared by means of a soluble Ziegler catalyst formed from biscyclopentadienyl zirconium dimethyl and methylaluminoxane. The overall activities lie between 100 and 1000 kg EPDM/(molZr h bar), obtainable at zirconium concentrations as low as 5 × 10^?7 mol/L. After an induction period (0.5–5 h) the polymerization rates increased and then leveled to a value which was constant for several days. From copolymerization kinetics reactivity ratios r₁₂ = 31.5, r₂₁ = 5 × 10^?3, and r₁₃ = 3.1 could be derived, and by ¹³C-NMR spectroscopy r₁₂ · r₂₁ = 0.3 was found (1: ethylene, 2: propylene and 3: ethylidene norbornene). The regiospecifity of the catalyst toward propylene leads exclusively to the formation of head-to-tail enchainments. The diene polymerizes via vinyl polymerization of the cyclic double bond, and the tendency to branching is low. Molecular weights were estimated between 40,000 and 160,000. The average molecular weight distribution of 1.7 is remarkably narrow. Glass transition temperatures of ?60 to ?50°C could be observed. The cure behavior and the physical properties of cured samples were also tested.     

Polymerization of Methyl Methacrylate by Charge-Transfer Mechanism with Amines and Carbon Tetrachloride

The charge-transfer complex formed between an amine and carbon tetrachloride can initiate the polymerization of vinyl monomers in a nonaqueous solvent such as dimethylsulfoxide. Here we use cyclopentylamine (CPA) and heptylamine (HA) as the donor compounds for charge-transfer initiation of the polymerization of methl methacrylate (MMA). The rate of polymerization R_p = k[MMA]¹ [amine]^0.5 [CCl₄]^0.5 when [CCl₄] [amine] ≤ 1; when [CCl₄] [amine] < 1, R_p becomes independent of [CCl₄] and R_p = k[MMA]^1.5 [amine]^0.5. The average constant at 60°C for the polymerization of MMA in terms of monomer were (1.66 ± 0.03) × 10^?5 and (1.46 ± 0.04) × 10^?5 s^?1 with CPA and HA, respectively, when [CCl₄] [amine] ≤ 1, and (1.16 ± 0.04) × 10^?5 and (1.39 ± 0.08) × 10^?1 L/mol·s when [CCl₄]/[amine] < 1.     

Allyl ethers as combined plasticizing and crosslinkable side groups in polycarbonate‐based polymer electrolytes for solid‐state Li batteries

Allyl ether‐functional polycarbonates, synthesized by organocatalytic ring‐opening polymerization of the six‐membered cyclic carbonate monomer 2‐allyloxymethyl‐2‐ethyltrimethylene carbonate, were used to prepare non‐polyether polymer electrolytes. UV‐crosslinking of the allyl side groups provided mechanically stable electrolytes with improved molecular flexibility—T_g below ?20 °C—and higher ionic conductivity—up to 4.3 × 10^?7 S/cm at 25 °C and 5.2 × 10^?6 S/cm at 60 °C—due to the plasticizing properties of the allyl ether side groups. The electrolyte function was additionally demonstrated in thin‐film Li battery cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2128–2135     

Reactive oligomers. I. Preparation and polymerization of ethylene glycol bis(methyl fumarate)

Ethylene glycol bis(methyl fumarate) (EGBMF) was prepared as a new type of divinyl compound and reactive oligomer: a needle crystal, m.p. 104.5°C. Homopolymerization of EGBMF was carried out in dioxane with 0.1 mol/L AIBN at [M] = 1 mol/L and 60°C; the rate of polymerization was estimated to be 4.44 × 10^?6 mol/L s in a good agreement with diethyl fumarate (DEF). The cyclization constant K_c was obtained as 1.64 mol/L, being rather low compared with diallyl oxalate which is 1,9-diene having two ester groups analogous to EGBMF. Gelatin occurred at about 35% conversion. Finally, the copolymerization of EGBMF (M₁) with diallyl phthalate (DAP) (M₂) is tentatively explored with the intention of the improvement of allyl resins in mechanical properties; remarkable rate enhancement was observed for copolymerization. The monomer reactivity ratios were estimated to be r₁ = 0.96 and r₂ = 0.025, the r₁ value being reduced compared with the DEF-DAP copolymerization system. These results are discussed from the standpoint of steric effect on the polymerization of fumarate as an internal olefin.     

Oxygen promoted radical polymerization of acrylonitrile in aqueous nitric acid. A kinetic study

The polymerization of acrylonitrile (AN) initiated by oxygen-ascorbic acid (AA)-ferric ion system was studied in dil. HNO₃ at 40°. The rate of polymerization, R_p, was found gravimetrically. In the [Fe³⁺] range, (2–5 × 10^?5 M, R_p was proportional to [AN]^{1.5 ± 0.05}, [O₂]^{0.5 ± 0.02} [AA]⁰ and [Fe³⁺]⁰; for [Fe³⁺] = (5–30) × 10^?5 M, it was proportional to [AN]^{1.8 ± 0.05}, [O₂]^{0.6 ± 0.02}, [AA]⁰ and [Fe³⁺]^{?0.9 ± 0.05}. A plausible reaction scheme is proposed and rate law presented to explain these results. R_p increased with ionic strength and [HNO₃] (up to ～0.25 M). An initial rate increase with temperature followed by a decrease was noticed. Chain lengths of the polymers were determined viscometrically.     

Graft Copolymerization on to Cellulose Using Binary Mixture of Monomers

The graft copolymerization of acrylonitrile (AN) and ethyl acrylate (EA) comonomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as an initiator in the presence of nitric acid at 35±0.1°C. The addition of ethyl acrylate as comonomer has shown a significant effect on overall and individual graft copolymerization of acrylonitrile on cellulose. The graft yield (%G_Y) and other grafting parameters viz. true grafting (%G_T), graft conversion (%C_G), cellulose number (Ng) and frequency of grafting (G_F) were evaluated on varying the concentration of comonomers from 6.0–30.0×10^?1 mol dm^?3 and ceric (IV) ions concentration from 2.5–25×10^?3 mol dm^?3 at constant feed composition (f_AN 0.6) and constant concentration of nitric acid (7.5×10^?2 mol dm^?3) in the reaction mixture. The graft yield (%G_Y) and other grafting parameters were optimal at 15×10^?1 mol dm^?3 concentration of comonomers and at 10×10^?3 mol dm^?3 concentration of ceric ammonium nitrate. The graft yield (%G_Y) and composition of grafted chains (F_AN) was optimal at a feed composition (f_AN) of 0.6. The energy of activation (Ea) for graft copolymerization has been found to be 16 kJ mol^?1. The molecular weight (Mw) and molecular weight distribution (Mw/Mn) of grafted chains was determined by GPC and found to be optimum at 15×10^?1 mol dm^?3 concentration of comonomer in the reaction mixture. The composition of grafted chains (F_AN) determined by IR method was used to calculate the reactivity ratios of monomers, which has been found to be 0.62 (r₁) and 1.52 (r₂), respectively for acrylonitrile (AN) and ethyl acrylate (EA) monomers used for graft copolymerization. The energy of activation for decomposition of cellulose and grafted cellulose was determining by using different models based on constant and different rate (β) of heating. Considering experimental observations, the reaction steps for graft copolymerization were proposed.     

Long branching in poly(vinyl acetate) and poly(vinyl alcohol). III. Kinetic study of the branching reaction in the radical polymerization of vinyl acetate

The branching reaction in the radical polymerization of vinyl acetate was studied kinetically. Branching occurs by polymer transfer as well as terminal double-bond copolymerization. The chain-transfer constants to the main chain (C_p,2) and to the acetoxy methyl group (C_p,1) on the polymer were calculated on the basis of the experimental data described in the preceding paper giving C_p,2 = 3.03 × 10^?4, C_p,1 = 1.27 × 10^?4 at 60°C, and C_p,2 = 2.48 × 10^?4, C_p,1 = 0.52 × 10^?4 at 0°C. Chain transfer to monomer is important with respect to the formation of the terminal double bond. The total values of transfer constants to the α- or β-position in the vinyl group and the acetoxymethyl group in vinyl acetate was determined to be 2.15 × 10^?4 at 60°C. The transfer constant to the acetyl group in the monomer (C_m,1) was also evaluated to be 2.26 × 10^?4 at 60°C from the quantitative determination of the carboxyl terminals in PVA. These facts suggest that the chain-transfer constant to the α- or β-position in the monomer (C_m,2) is nearly equal to zero within experimental error. Copolymerization reactivity parameters of the terminal double bond were also estimated. In conclusion, it has become clear that the formation of nonhydrolyzable branching by the terminal double-bond reaction can be almost neglected, and hence that the long branching in PVA is formed only by the polymer transfer mechanism. On the other hand, a large number of hydrolyzable branches in PVAc are prepared by the terminal double-bond reaction rather than by polymer transfer.