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1.
Aniline markedly accelerated polymerization of methyl methacrylate initiated by metal chelates of β-diketones. The kinetic studies of the polymerizaion of methyl methacrylate initiated by Ni (II) acetyl acetonate in the presence of aniline yielded Rp=[I]0.55 [A]0.66 [M]1.87. The polymerization was of free radical in character. The accelerating effect of aniline was attributed to its reduction activation of the chelate. The activation energy for the overall polymerization was 21.3Kcal/mole, which yielded 33.4Kcal/mole for the activation energy for the initiation. 相似文献
2.
Minoru Imoto Takamasa Maeda Tatsuro Ouchi 《Journal of polymer science. Part A, Polymer chemistry》1979,17(2):385-392
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: Rp = 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. 相似文献
3.
A diblock copolymer, poly(methyl methacrylate)-b-polystyrene (PMMA-b-PS), was grafted onto the surface of nano-titania (nano-TiO2) successfully via reversible addition-fragmentation chain transfer (RAFT) polymerization. The surface of TiO2 nanoparticles was modified initially by attaching dithioester groups to the surface using silane coupling agent 3-(chloropropyl)triethoxy silane and sodium ethyl xanthate. The polymerization of methyl methacrylate and styrene were then initiated and propagated on the TiO2 surface by RAFT polymerization. The resulting composite nanoparticles were characterized by means of XPS, FT-IR, 1H NMR and TGA. The results confirmed the successful grafting of poly(methyl methacrylate) (PMMA) and diblock copolymer chains onto the surface of TiO2. The amount of PMMA grafted onto the TiO2 surface increased with the polymerization time. Moreover, the kinetic studies revealed that the ln([M]0/[M]), where [M]0 is the initial and [M] is the time dependent monomer concentrations, increased linearly with the polymerization time, indicating the living characteristics of the RAFT polymerization. 相似文献
4.
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 (Rp) was found to be expressed by the rate equation: Rp = 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. 相似文献
5.
The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]2Ni ( 1 , [NN] = [2‐C(H)NAr‐5‐tBu‐C4H2N]?, Ar = 2,6‐iPr2C6H3) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh3)2] in THF. Reaction of [NN]Li with NiBr2(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] ( 2 ). Complexes 1 and 2 were characterized by 1H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
The kinetics of polymerization of tributyltin methacrylate (TBTM) has been studied in benzene solution in the temperature range 60–75°C in the presence of azobisisobutyronitrile (AIBN). We have obtained the following polymerization rate equation: R p = K p [TBTM]1.5 [AIBN]0.5. It shows that the dependence of the polymerization rate on the concentrations of the monomer TBTM and the initiator AIBN are 1.5 and 0.5 order, respectively. The activation energy of polymerization was found to be 18.1 kcal/mol. The activation energy for the degree of polymerization is approximately -12.3 kcal/mol. 相似文献
7.
The polymerization of methyl methacrylate was carried out with the following Ziegler-Natta type initiating systems: Fe(AcAc)3-AlEt2Br, Fe(AcAc)3-ZnEt2 (acac = acetyl acetonate). Both the catalyst systems are active under homogeneous conditions in benzene at 40°C for methyl methacrylate polymerization. The polymerization kinetics suggests that the average rate of polymerization was first order with respect to [monomer] for both the catalyst systems, and the overall activation energies were found to be 14.0 and 12.8 kcal mol ?1. 相似文献
8.
The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (Rp0) and steady-state polymerization rate (Rp) were proportional to the mass ratio between water
and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: Rp0∝[I]0.71[S]0.23.The above exponents were close to those obtained from
normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methylmethacrylate) decreased as the polymerization temperature,[I]and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization. 相似文献
9.
The aqueous heterogeneous polymerization of methyl methacrylate (MMA) initiated by the Ce4+-glycolic acid (GA) redox system was studied at 35 × 0.2°C under a nitrogen atmosphere. The rate of monomer disappearance was proportional to [MMA]1[GA]1[Ce4+]°, and the rate of eerie ion disappearance was found to be directly proportional to [Ce4+] and [GA] but independent of [MMA]. The activation energy was found to be 34 kJ/mol. The molecular weight of polymethyl methacrylate increased with increasing [MMA] and decreased with increasing [oxidant]. The effect of increasing [H2SO4] on polymerization was also studied. The results are compared with those obtained for the aqueous homogeneous polymerization of acrylamide with the same redox pair. 相似文献
10.
Victor Bulacovschi Camelia Mihǎilescu Silvia Ioan Bogdan C. Simionescu 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):613-622
The kinetics of phase-transfer-agent-aided free radical polymerization of methyl methacrylate was investigated by using K2S2O8 as the initiator and cetyltrimethyl ammonium chloride (Arquad) as the phase transfer agent. The rate of polymerization was found to be proportional to [M]1.23[K2S2O8]0.8 [Arquad]0.25 and almost independent of the volume of water (V w)/volume of organic solvent (V o) (benzene) ratio for V w/V o < 0.33. A reaction mechanism is proposed. 相似文献
11.
Natsuki Yamashita Hiroyuki Tanaka Satoru Deguchi Toshihisa Maeshima Lun-Shin Wei 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1121-1134
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, Rp , was expressed by Rp = k[Im] [MMA]2, where k = 3.0 × 10?6 L2/(mol2 s) in THF at 30°C. The overall activation energy, Ea , was 6.9 kcal/mol for the Im system and 7.3 kcal/mol for the 2MIm system. The relation between logRp 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. 相似文献
12.
Zenjiro Osawa Masami Sorimachi Hitoshi Kanazawa Yoshitaka Ogiwara 《Journal of polymer science. Part A, Polymer chemistry》1973,11(3):523-533
Polymerization of methyl methacrylate with some cobalt (III) complexes was carried out in various solvents and in mixed solvents of acetone and water or alcohols. Sodium hexanitrocobaltate(III) was found to be an effective initiator in mixed solvent of water and acetone. The kinetic study on the polymerization of methyl methacrylate with Na3[Co(NO2)6] in a water-acetone mixed solvent gave the following over-all rate equation: Rp = 8.04 × 104 exp{ ?13,500/RT} [I]1/2[M]2 (mol/1.?sec). The effects of various additives on polymerization rate and the copolymerization curve with styrene suggest that polymerization proceeds via a radical mechanism. The dependence of the polymerization rate on the square of monomer concentration and the spectroscopic data were indicative of the formation of a complex between initiator and monomer. 相似文献
13.
R. S. Tewari Anita Bajpai A. K. Srivastava 《Journal of polymer science. Part A, Polymer chemistry》1985,23(9):2405-2411
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 (Rp) 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. 相似文献
14.
The kintetic studies of polymerization of methyl methacrylate initiated with nickel ethyl acetoacetate gave the following equations. Rp=K1[Monomer]1.4[Chelate]0.5, in the absence ox aniline Rp=K2[Monomer]1.2[Chelate]0.5 [Aniline]0,5, in the presence of aniline. Some aromatic amines such as aniline markedly accelerated the polymerization, while pyridine had no such effect. The activation energy of initiation was 24.8 kcal/mol in the absence of aniline, and 8.8 kcal/mol in the presence of aniline. Both the kinetic data and the infrared spectra of the polymer indicated that the polymerization was radical in nature. The reaction order against monomer varied, as the temperature differed. The spectrophotometric investigation indicated formation of a complex between the chelate and the monomer, or amines. It also showed that the formation of a complex was not a factor which controlled the rate of initiation. A scheme of initiation mechanism was presented on the basis of the above experimental evidence. 相似文献
15.
Abstract The kinetics of phase-transfer-agent-assisted free-radical polymerization of methyl methacrylate using K2S2O8 as the water-soluble initiator and triethylbenzylammonium chloride (TEBA) as the phase-transfer catalyst (PTC) was investigated in toluene-water biphase media at 60°C. The effect of varying [MMA], [K2S2O8], [TEBA], [H+], the ionic strength of the medium, and the temperature on the rate of polymerization (R p) was studied. R p was found to be proportional to [MMA]2, [K2S2O8]1, and [TEBA]0.5. Based on the kinetic results, a mechanism involving initiation of polymerization by phase-transferred S2O8 2- and termination by Q+ (quaternary ammonium ion) is proposed. 相似文献
16.
Tsuneyuki Sato Takayuki Oki Makiko Seno Tomohiro Hirano 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1269-1279
3‐Ethyl‐3‐methacryloyloxymethyloxetane (EMO) was easily polymerized by dimethyl 2,2′‐azobisisobutyrate (MAIB) as the radical initiator through the opening of the vinyl group. The initial polymerization rate (Rp) at 50 °C in benzene was given by Rp = k[MAIB]0.55 [EMO]1.2. The overall activation energy of the polymerization was estimated to be 87 kJ/mol. The number‐average molecular weight (M?n) of the resulting poly(EMO)s was in the range of 1–3.3 × 105. The polymerization system was found to involve electron spin resonance (ESR) observable propagating poly(EMO) radicals under practical polymerization conditions. ESR‐determined rate constants of propagation (kp) and termination (kt) at 60 °C are 120 and 2.41 × 105 L/mol s, respectively—much lower than those of the usual methacrylate esters such as methyl methacrylate and glycidyl methacrylate. The radical copolymerization of EMO (M1) with styrene (M2) at 60 °C gave the following copolymerization parameters: r1 = 0.53, r2 = 0.43, Q1 = 0.87, and e1 = +0.42. EMO was also observed to be polymerized by BF3OEt2 as the cationic initiator through the opening of the oxetane ring. The M?n of the resulting polymer was in the range of 650–3100. The cationic polymerization of radically formed poly(EMO) provided a crosslinked polymer showing distinguishably different thermal behaviors from those of the radical and cationic poly(EMO)s. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1269–1279, 2001 相似文献
17.
The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (R_p) isR_p=9.7 x 10~(12) e~(-21.200/RT) [MMA]~(O.88)[Na_2 SO_3]~(0.50)The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ=1.2x10~(12)e~(-15.600/RT)[Na_2SO_3]=K_τR_iThe polymerization is initiated by a primary radical generated from the redox reaction rather than induced by "coordination-proton transfer" mechanism. 相似文献
18.
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. 相似文献
19.
Bianca S. Shemper A. Ersin Acar Lon J. Mathias 《Journal of polymer science. Part A, Polymer chemistry》2002,40(3):334-343
The copper‐catalyzed atom transfer radical polymerization (ATRP) of poly(propylene glycol) methacrylate (PPGM) in solution to produce linear and starlike polymers is reported, using methylethyl ketone as the solvent and a temperature of 80 °C. The ATRP system used was efficient for polymerization of the functionalized monomer without protecting hydroxyl end groups of monomer. The polymerizations were consistent with “living” or controlled processes, as revealed by the linear evolution of molecular weight with conversion. Increasing the [M]0:[I]0 ratio resulted in increasing molecular weights, whereas the polydispersity indices remained low (Mw/Mn < 1.4) even at high conversion. Decreasing the [CuBr]0:[I]0 ratio resulted in lower conversions, slightly larger polydispersities, and decreased molecular weights, likely resulting from a lower initiation efficiency. Polymers were characterized by 1H and 13C NMR; molecular weights of polymers with low degrees of polymerization were estimated by end‐group analysis from 13C NMR spectra obtained using distortionless enhancement by polarization transfer and the gated decoupling techniques. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 334–343, 2002 相似文献
20.
Yutaka Miura Toshifumi Satoh Atsushi Narumi Osamu Nishizawa Yoshio Okamoto Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(4):1436-1446
The copper‐mediated atom transfer radical polymerization of methyl methacrylate (MMA) in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) was studied to simultaneously control the molecular weight and tacticity. The polymerization using tris[2‐(dimethylamino)ethyl]amine (Me6TREN) as a ligand was performed even at ?78°C with a number‐average molecular weight (Mn) of 13,400 and a polydispersity (weight‐average molecular weight/number‐average molecular weight) of 1.31, although the measured Mn's were much higher than the theoretical ones. The addition of copper(II) bromide (CuBr2) apparently affected the early stage of the polymerization; that is, the polymerization could proceed in a controlled manner under the condition of [MMA]0/[methyl α‐bromoisobutyrate]0/[CuBr]0/[CuBr2]0/[Me6TREN]0 = 200/1/1/0.2/1.2 at ?20°C with an MMA/HFIP ratio of 1/4 (v/v). For the field desorption mass spectrum of CuIBr/Me6TREN in HFIP, there were [Cu(Me6TREN)Br]+ and [Cu(Me6TREN)OCH(CF3)2]+, indicating that HFIP should coordinate to the CuI/Me6TREN complex. The syndiotacticity of the obtained poly(methyl methacrylate)s increased with the decreasing polymerization temperature; the racemo content was 84% for ?78°C, 77% for ?30°C, 75% for ?20°C, and 63% for 30°C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1436–1446, 2006 相似文献