甲基丙烯酸三乙基锡酯的聚合反应动力学的研究

<正> 有机锡聚合物可以用于防污涂料,与低分子有机锡化合物相比,具有低环境污染、长效等特点。近年来,人们对有机锡单体的合成、纯化、聚合和共聚合进行了研究,但有关动力学的研究报道甚少,而甲基丙烯酸三乙基锡酯(TETM)的聚合动力学未见报道。     

Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

Kinetic and ESR studies on the radical polymerization of Di-n-butyl itaconate in benzene

The polymerization of di-n-butyl itaconate (DBI) intiated with AIBN was kinetically investigated in benezene. The polymerization rate (R_p) was expressed by: R_p = k[AIBN]^0.5[DBI]^1.7. The polymerization showed a considerably low overall activation energy of 15.3 kcal/mol. The initiator efficiency of AIBN in this system decreased with increasing DBI concentration, ranging from 0.34 to 0.55°C, which is ascribable to viscosity effect due to the monomer. From an ESR study, the polymerization system was found to involve two kinds of persistent radicals, namely, primary propagating ( III ) and propagating ( I ) radicals. The relative concentration of III to I increased with decreasing monomer concentration. Azo-nitrile initiators such as AVN and ACN similarly produced two persistent radicals, while MAIB, DBPO, and PBO yielded only propagating radical I as persistent. The MAIB-initiated polymerization of DBI was also performed in benzene. Similar kinetic features were observed, that is, a higher dependence of R_p on the DBI concentration and a low overall activation energy (14.4 kcal/mol). The following rate equation was obtained at 50°C:R_p = k[MAIB]^0.5[DBI]^1.6. The initiator efficiency of MAIB decreased with increasing DBI concentration, ranging from 0.32 to 0.53 at 50°C. The concentration of propagating radical I was determined by ESR at 50 and 61°C, from which k_p and k_t were estimated. The k_p value increased with increasing monomer concentration, while the k_t one decreased with the DBI concentration. These values are much lower compared with those of MMA.     

Long-lived polymer radicals. VI. Polymerization of N-methylmethacrylamide with formation of living propagation radicals

The polymerization of N-methylmethacrylamide (NMMAm) with azobisisobutyronitrile (AIBN) was investigated kinetically in benzene. This polymerization proceeded heterogeously with formation of the very stable poly(NMMAm) radicals. The overall activation energy of this polymerization was calculated to be 23 kcal/mol. The polymerization rate (R_p) was expressed by: R_p = k[AIBN]^0.63-0.68[NMMAm]^1?2.5. Dependence of R_p on the monomer concentration increased with increasing NMMAm concentration. From an ESR study, cyanopropyl radicals escaping the solvent cage were found to be converted to the living propagating radicals of NMMAm in very high yields (ca. 90%). Formation mechanism of the living polymer radicals was discussed on the basis of kinetic, ESR spectroscopic, and electron microscopic results.     

SYNTHESIS AND POLYMERIZATION OF ALIPHATIC TERTIARY AMINO-GROUP N-SUBSTITUTED ACRYLAMIDES

Aliphatic tertiary amino-group N-substituted acrylamides, N-acryl-N′-methylpiperazine (AMP)and N-methacryl-N′-methylpiperazine (MAMP) were synthesized directly from N-methylpiperazinewith corresponding acryloyl chlorides and characterized by elementary analysis of their picrates,~1H-NMR, IR and MS. AMP did not polymerize with benzoyl peroxide (BPO), but could poly-merize with lauroyl peroxide (LPO). The rate equation of the polymerization was given as R_P=K_P [AMP]~(1.5)[LPO]~(0.5) and the overall activation energy of this polymerization system was 10.8Kcal/mol. The redox nature of LPO with the monomer itself was suggested. Even though AMP and MAMP hardly proceed the polymerization initiated with BPO, butunder lower concentration would form redox system with BPO to initiate the polymerization of MMAreadily. The rate equation of the polymerization of MMA initiated with MAMP-BPO systemwas given as R_P=K_P [MMA] [MAMP}~(0.5) [BPO]~(0.5) and the overall activation energy was 10.2Kcal/mol. The analysis of the obtained polymers confirmed that MAMP not only initiated the poly-merization of MMA by combining with BPO, but also took part in the polymer chains impartingthem with better biocompatibility.     

Vinyl polymerization initiated by peroxydiphosphate. V. Polymerization of acrylonitrile initiated by peroxydiphosphate-cyclohexanol redox system in the presence of silver ion

The polymerization of acrylonitrile was carried out using peroxydiphosphate-cyclohexanol redox system in the presence of silver ion. The rate of polymerization increases with increasing peroxydiphosphate concentration and the initiator exponent was computed to be 0.5. The rate of polymerization increases with increasing monomer concentration and the monomer exponent was computed to be unity. The plot of R_p vs [Ag⁺]^1/2 was linear, indicating 0.5 order with respect to [Ag⁺]. The reaction was carried out at three different temperatures and the overall activation energy was calculated to be 7.60 kcal/mol. The effect of certain surfactants on the rate of polymerization has been investigated and a suitable kinetic scheme has been pictured.     

Vinyl polymerization. Part 268. Polymerization of acrylonitrile initiated by the system of tetramethyl tetrazene and bromoacetic acid

The polymerization of acrylonitrile (AN) initiated by the system of tetramethyl tetrazene (TMT) and bromoacetic acid (BA) in dimethylformamide (DMF) was studied. The TMT–BA system could initiate the polymerization of AN more easily than TMT alone. The polymerization was confirmed to proceed through a radical mechanism. The initial rate of polymerization R_p was expressed by the equation: R_p = [TMT]^0.62-[BA]^0.5[AN]^1.5. The overall activation energy for the polymerization was estimated as 9.4 kcal/mole. In the absence of monomer, the reaction of TMT with BA in DMF was also studied kinetically by measuring the evolution of nitrogen gas. The reaction was first-order in TMT and first-order in BA; the rate data at 49°C were k₂ = 9.1 × 10^?2l./mole-sec., ΔH? = 17.0 kcal/mole, and ΔS? = ? 6.6 eu. In addition, the treatment of TMT with BA in benzene led to the formation of tetramethylhydrazine radical cation, which was identified by its ESR spectrum. On the other hand, the relatively strong interaction between TMT and DMF was observed by absorption spectrophotometry.     

Sulfur-Containing Vinyl Monomers. XIX. Radical Polymerization of 2-Mercaptobenzothiazolyl Methacrylate

2-Mercaptobenzothiazolyl methacrylate (MBTM) was synthesized by the reaction of 2-mercaptobenzothiazole and methacrylyl chloride in tetrahydrofuran at -18°C. MBTM was found to polymerize in the presence of 2,2′-azobisisobutyronitrile (AIBN), n-BuLi, and UV light. From the kinetic studies of radical polymerization of MBTM with AIBN in benzene at 60°C, the overall activation energy was determined to be 18.9 kcal/mole, and the rate of polymerization (R) was expressed as R_p = k[AIBN]^0.5 [MBTM], where k is the overall polymerization rate constant. From these results this polymerization was confirmed to proceed via an ordinary radical mechanism. This monomer (M₂) was also copolymerized radically with styrene (M₁) at 60°C, and the resulting copolymerization parameters were determined as r₁ = 0.042, r₂ = 0.20, Q₂ = 4.09, and e₂ = 1.39. The thermal stability and the photodegradation behavior of the polymers were examined, and they were compared with those of the related polymers.     

The use of ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator for the polymerization of methyl methacrylate

The thermal polymerization of methyl methacrylate [MMA] was carried out using ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator. The rate of polymerization (R_p) increases with increasing monomer and initiator concentrations; The exponent value has been computed to be 1 ± 0.02 and 0.5, respectively. The reaction was carried out at four different temperatures and the overall activation energy has been computed to be 16.01 kcal/mol. The polymerization was inhibited in the presence of hydroquinone as a radical scavanger. Kinetic studies indicates that the overall polymerization takes place by a radical mechanism.     

Radical‐initiated polymerization of β‐methyl‐α‐methylene‐γ‐butyrolactone

β‐Methyl‐α‐methylene‐γ‐butyrolactone (MMBL) was synthesized and then was polymerized in an N,N‐dimethylformamide (DMF) solution with 2,2‐azobisisobutyronitrile (AIBN) initiation. The homopolymer of MMBL was soluble in DMF and acetonitrile. MMBL was homopolymerized without competing depolymerization from 50 to 70 °C. The rate of polymerization (R_p) for MMBL followed the kinetic expression R_p = [AIBN]^0.54[MMBL]^1.04. The overall activation energy was calculated to be 86.9 kJ/mol, k_p/k_t^1/2 was equal to 0.050 (where k_p is the rate constant for propagation and k_t is the rate constant for termination), and the rate of initiation was 2.17 × 10^?8 mol L^?1 s^?1. The free energy of activation, the activation enthalpy, and the activation entropy were 106.0, 84.1, and 0.0658 kJ mol^?1, respectively, for homopolymerization. The initiation efficiency was approximately 1. Styrene and MMBL were copolymerized in DMF solutions at 60 °C with AIBN as the initiator. The reactivity ratios (r₁ = 0.22 and r₂ = 0.73) for this copolymerization were calculated with the Kelen–Tudos method. The general reactivity parameter Q and the polarity parameter e for MMBL were calculated to be 1.54 and 0.55, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1759–1777, 2003     

Vinyl polymerization. 364. Polymerization of methyl methacrylate initiated with benzaldehyde

Benzaldehyde (PhCHO) is found to be able to initiate the radical polymerization of methyl methacrylate (MMA). The rate of polymerization is expressed by the following equation: R_p = const[PhCHO]^0.5[MMA]^1.5. The overall activation energy is estimated to be 56.3 kJ mole^?1. The mechanism of polymerization is discussed.     

Polymerization of Methyl Methacrylate in the Presence of Imidazole Derivatives. Kinetics and Polymer Structure

The kinetics of the polymerization of methyl methacrylate (MMA) in the presence of imidazole (Im), 2-methylimidazole (2MIm), or benz-imidazole (BIm) in tetrahydrofuran (THF) at 15–40°C was investigated by dilatometry. The rate of polymerization, R_p , was expressed by R_p = k[Im] [MMA]², where k = 3.0 × 10^?6 L²/(mol² s) in THF at 30°C. The overall activation energy, E_a , was 6.9 kcal/mol for the Im system and 7.3 kcal/mol for the 2MIm system. The relation between logR_p and 1 T was not linear for the BIm system. The polymers obtained were soluble in acetone, chloroform, benzene, and THF. The melting points of the polymers were in the range of 258–280°C. The ¹H-NMR spectra indicated that the polymers were made up of about 58–72% of syndiotactic structure. The polymerization mechanism is discussed on the basis of these results.     

Polymerization of 1,3‐dienes with functional groups. II. Free‐radical polymerization of N‐(2‐methylene‐3‐butenoyl)piperidine

The free‐radical homopolymerization and copolymerization behavior of N‐(2‐methylene‐3‐butenoyl)piperidine was investigated. When the monomer was heated in bulk at 60 °C for 25 h without an initiator, about 30% of the monomer was consumed by the thermal polymerization and the Diels–Alder reaction. No such side reaction was observed when the polymerization was carried out in a benzene solution with 1 mol % 2,2′‐azobisisobutylonitrile (AIBN) as an initiator. The polymerization rate equation was found to be R_p ∝ [AIBN]^0.507[M]^1.04, and the overall activation energy of polymerization was calculated to be 89.5 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure that included both 1,4‐E and 1,4‐Z configurations. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were carried out in benzene solutions at 60 °C with AIBN as an initiator. In the copolymerization with styrene, the monomer reactivity ratios were r₁ = 6.10 and r₂ = 0.03, and the Q and e values were calculated to be 10.8 and 0.45, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1545–1552, 2003     

Polymerization of N-acryloyl pyrrolidone and synthesis of graft copolymer by using the mechanism of initiation of anionic ring-opening polymerization

N-acryloyl pyrrolidone (NAP) was synthesized by reaction of pyrrolidone with acryloyl chloride. First, the polymerization of NAP and copolymerization of NAP with styrene (St) were carried out at 60°C, using 2,2′-azobisisobutyronitrile (AIBN) as an initiator. Kinetic studies showed that the rate of polymerization (R_p) could be expressed by R_p = K [AIBN]^0.5 [NAP]^1.0. The reactivity of NAP was found to be larger than that of N-methacryloyl pyrrolidone. The overall activation energy was calculated to be 24.3 kcal mole^?1. The following monomer reactivity ratio and Q and e values were obtained. NAP(M₁)—St(M₂): r₁ = 1.50, r₂ = 0.35, Q₁ = 0.42, and e₁ = 1.60. Second, graft copolymers were synthesized by reacting pyrrolidone, in the presence of a catalytic amount of its potassium salt, with poly(NAP-co-St).     

Kinetics of the Copolymerization of Methyl Vinyl Ketone and Acrylamide Initiated by the Adduct of Methyl Vinyl Ketone and Imidazole

N-(Butyl-3-one)imidazole acts as an initiating adduct which is formed in the anionic polymerization of methyl vinyl ketone (MVK) induced by imidazole (Im) and is directly formed from Im and the MVK monomer. The kinetics of the anionic homopolymerization of MVK and acrylamide (AAm) under argon in the presence of the adduct were investigated in tetrahydrofuran (THF). The rate of polymerization for the MVK system is expressed as R_p = k[Adduct] [MVK], where k = 3.1 × 10^?6 L/(mol·s)in THF at 30°C. The overall activation energy, E_a , was found to be 5.34 kcal/mol. The R_p for the AAm system is expressed as R_p = k[Adduct] [AAm], where k = 6.8 × 10^?6 L/(mol·s) in THF at 30°C, with E_a 7.78 kcal/mol. The mechanism of the polymerization induced by the initiator adduct is discussed on the basis of these results.     

Radical polymerization of 2-methacryloyloxyethyl phosphorylcholine in water: kinetics and salt effects

The homogeneous polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) as betaine monomer with potassium peroxydisulfate (KPS) was kinetically investigated in water by means of FT-near IR spectroscopy. The overall activation energy of the polymerization was estimated to be 12.8 kcal/mol. The initial polymerization rate (R_p) at 40 °C was given by R_p = k[KPS]^0.98[MPC]^1.9. The presence of alkaline metal halides accelerated the polymerization. The larger the radius of metal cation or halide ion was, the larger the accelerating effect was. The accelerating salt effect was explained by interactions of salt ions with ionic moieties of the propagating polymer radical and/or the MPC monomer. A kinetic study was also performed on the polymerization of MPC with KPS in water in the presence of NaCl of 2.5 mol/l. R_p at 40 °C was expressed by R_p = k[KPS]^0.6[MPC]^1.6. A very low value of 4.7 kcal/mol was obtained as the overall activation energy of the polymerization.     

A New Redox Initiating System for the Polymerization of Vinyl Monomers

Abstract

A new redox system, dioxane-ascorbic acid, has been investigated for the homopolymerization of vinyl monomers. Detailed kinetic studies on the aqueous polymerization of acrylamide by this initiating system have been done iodometrically at 35 ± 0.2°C. The effect of various additives, such as organic solvents, inorganic salts, surfactants, etc., on the rate of polymerization has been studied. The retardation constants for organic solvents have been evaluated by the “intercept method.” The overall energy of activation has been found to be 8.75 kcal/deg/mol, within the temperature range 25–45°C. A suitable mechanism has been suggested. The following rate expression: R_p α [acrylamide]^1.0 [dioxane]^1.0 [ascorbic acid]⁰, has been observed.     

Polymerization of Acrylamide Initiated by the Redox System Potassium Persulfate/Lactic Acid,Catalyzed by Silver Ions

The aqueous polymerization of acrylamide initiated by the potassium persulfate/lactic acid system catalyzed by Ag⁺ ions has been studied iodometrically over the temperature range from 35 to 50 ± 0.2°C. The rate of polymerization is governed by the expression R_p ∞ [M]^0.8[K₂S₂O₈]^1.0[Ag]^1.0 The deviation from normal kinetics has been studied. A tentative mechanism of initiation is suggested. The overall energy of activation is 5.52 kcal/mol.     

Polymerization of 1,3‐dienes with functional groups. III. Free‐radical polymerization of N,N‐diethyl‐2‐methylene‐3‐butenamide

Free‐radical homo‐ and copolymerization behavior of N,N‐diethyl‐2‐methylene‐3‐butenamide (DEA) was investigated. When the monomer was heated in bulk at 60 °C for 25 h without initiator, rubbery, solid gel was formed by the thermal polymerization. No such reaction was observed when the polymerization was carried out in 2 mol/L of benzene solution with with 1 mol % of azobisisobutyronitrile (AIBN) as an initiator. The polymerization rate (R_p) equation was R_p ∝ [DEA]^1.1[AIBN]^0.51, and the overall activation energy of polymerization was calculated 84.1 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure where both 1,4‐E and 1,4‐Z structures were included. From the product analysis of the telomerization with tert‐butylmercaptan as a telogen, the modes of monomer addition were estimated to be both 1,4‐ and 4,1‐addition. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were also carried out in benzene solution at 60 °C. In the copolymerization with styrene, the monomer reactivity ratios obtained were r₁ = 5.83 and r₂ = 0.05, and the Q and e values were Q = 8.4 and e = 0.33, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 999–1007, 2004     

Polymerization of Methacrylamide Initiated by the Persulfate/Thiolactic Acid Redox System

The aqueous polymerization of methacrylamide initiated by the ammonium persulfate/thiolactic acid redox system has been studied at 35 ± 0.2°C. The rate of polymerization is governed by the expression, R_p + K_p [MAA] ^1.33 [TLA]^0.22 [ammonium persulfate]^0.6. The deviations from normal kinetics are discussed. A tentative mechanism of initiation is given. The temperature dependence of the rate of polymerization has been studied over the range 30–55°C. The overall activation energy of polymerization is 10.4 kcal/mole.