"CAGE" VANADYL POLYCARBOXYLATE-THIOUREA COMPLEX FOR THE POLYMERIZATION OF ACRYLONITRILE

The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by " cage " vanadyl polycarboxylate (P=VO)-thiourea (TU) complex was investigated. The overall rate ofpolymerization isThe relationship between the induction period (τ) and the temperature of polymerization as well as the concentrations of reactants can be expressed as follows :The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreases with increasing temperature of polymerization and concentrations of vanadyl polycarboxylate and thioureaThe polymerization mechanism was proposed and discussed.     

STUDIES ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY METAVANADATE-CONTAININ G ANION EXCHANGER-THIOUREA REDOX SYSTEM

The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by metavanadate-containing anion exchange resin (PV)-thiourea (TU) redox system at 20—40℃. has been investigated. The overall rate of polymerization (R_p) is given byR_p=1.92×10~4e~(-6.860/RT) [AN]~(1.2) [PV]~(0.44) [TU]~(1.0)[HNO_3]~(1.0)The kinetic parameters differed from those of V~(5+)-TU system indicated that the generation of the primary radicals is mainly a difffusion-controlled reaction. The effect of macromolecular field arisen from the polymer matrix exerts a great influence on the polymerization process.     

STUDY ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY POLYPROPYLENE-BASED VANADYL POLYIMIDODIACETATE——THIOUREA REDOX SYSTEM

The present paper deals with the kinetics of polymerization of acrylonitrile (AN) initialed by the redox system of polypropylene-based vanadyi polyimidodiacetate (PV)-thiourea (TU)in aqueous sulfuric acid in the temperature range from 25 to 40℃. The polymerization rate was measured by varying the concentrations of monomer, vanadyl polyimidodiacetate, thiourea and sulfuric acid. The overall rate of polymerization was summarized asRp=2.2×10~5e~(-6.560/RT) [AN]~(1.0)[PV]~(0.50)[TU]~(1.5)[H_2SO_4]~(2.0)The molecular weight of polyacrylonitrile based on the experimental data was:(?)=k 1/T [pv]~(0.50)[TU]~(1.5)[H_2SO_4]~(2.0)These results indicated that the chain radicals are terminated by combination and/or disproportionation rather than chain transfer. The cooperation effect of carboxylic groups and the macromolecular field effect of polymer supporter are the characters of vanadyl polyimidodiacetate such as the case reported in early paper.     

KINETIC STUDIES ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY METALLIC MAGNESIUM-NITRIC ACID SYSTEM

This article reports the polymerization kinetics of acrylonitrile initiated by metallic magnesiumnitric acid system. The rate of polymerization is independent of the amount of magnesium used; when the concentration of nitric acid is higher than acrylonitrile, the equation of polymerization kinetics may be expressed asR_p =1.91×10~5e~(-15000)/RT[Mg]~0 [AN]~(2.2) [HNO_3]~(0.45)The result of copolymerization of acyrlonitrile and methyl acrylate supports a free-radical mechanism.     

Vinyl polymerization with Fe(III)–thiourea as initiator system. Part II. Kinetics: Predominant primary radical termination

The rate of polymerization R_p of methyl methacrylate initiated by Fe(CIO₄)₃ and thiourea (TU) in tert-butyl alcohol is indepenent of [Fe(III)] and [TU] in the concentration range studied. In contrast to R_p, the degree of polymerization DP changes markedly with the change in the initiator concentration. DP is overwhelmingly lower than is expected in a standard radical polymerization at the same R_p. Further, R_p is proportional to the square of the monomer concentration. Initiation efficiency is less than one. Independent experiments proved that in the azobisisobutyronitrile-initiated polymerization the R_p and DP are negligibly affected by [Fe(CIO₄)₃] or [TU], though high [TU] brings about high induction periods. The results of Fe(III)-TU-initiated polymerization have been interpreted in terms of the predominant termination of polymer radicals by primary radicals.     

阴离子交换树脂负载钒(V)—硫脲氧化还原体系引发丙烯腈聚合的研究

用负载偏钒酸根的强碱性阴离子交换树脂(PV)与硫脲(TU)组成氧化还原体系在硝酸溶液中引发丙烯腈(AN)聚合,表观聚合速度是: R=1.92×10~4e~(-6860)/RT[AN]~(1.2)[RV]~(0.44)[TU]~(1.8)[HNO_ 3]~(1.0)聚合动力学参数与V~(6+)—TU体系所得者不同,表明初级自由基的产生受扩散控制因素的重要影响,并且载体树脂在聚合过程中存在着强烈的大分子场效应。聚合诱导期(ι)与引发速度成反比。聚合物分子量与聚合速度成正比,与终止速度和聚合温度成反比。加料方式实验再一次表明了引发种是由五价钒和硫脲络合和/或缔合所产生而不是和异硫脲结合的结果。本文讨论了引发聚合机理。     

钒化合物引发丙烯腈聚合──高分子场效应

研究了酸性介质中五价钒氧离子（VO）、强碱性阴离子交换树脂负载钒（V）（BAEV）、硫酸氧钒（VOSO4）、杨梅形聚羧酸氧钒（IV）（APCV）、杨酸形聚亚氨二乙酸氧钒（IV）（APIV）、杨梅形聚得偕亚氨二乙酸氧钒（IV）（APOV）、笼形聚羧酸氧钒（IV）（CPCV）和笼形聚肟偕亚氨二乙酸氧钒（IV）（CPOV）等与硫脲（TU）配住生成活性种并引发丙烯腈（AN）聚合反应。表观聚合速度（Rp）分别是：VO-TU:Rp=2.8X105e-14200/RTC2.2'(AN)c.20(HNO3)c0(V5+)c1.3(TU)BAEV-TU:Rp=1.9X104e-6860/RTc1.2(AN)c1.0'(HNO3)c0.44(PV)c1.0(TU)VOSO4-TU:Rp=0APCV-TU:Rp=2.3X104e-4100/Rtc1.5(AN)c1.5(HNO3)c0.5(PV)c2.0(TU)APIV-TU:RP=2.2X105e-6860/RTc1.0(AN)c2.0(H2SO4)c0.5(PV)c1.5(TU)APOV-TU:RP=1.9X108e-10800/RTc.10(AN)c1.0(HNO3)c0.6(PV)c1.5(TU)CPCV-TU:Rp=9.7X105e-10500/RTc1.0(AN)c1.5(HNO3)c0.5(PV)c0.76(TU)CPOV-TU:Rp=1.0X108e-10500/RTc1.0(AN)c3.0(HNO3)c1.0(PV)c1.5(TU)根据实验结果,认为：（一）钒化合物与硫脲在酸性介质中通过“逐步配位—质子转移”机理产生引发种;（二）钒络合物及其活化后所产生的阳离子自由基（i＝0,1,2,…,n）处于大分子引力场内进行链引发,在某些情况下,原地进行键增长反     

Metal compounds in free-radical processes. III. Polymerization of acrylonitrile initiated by copper (II) nitrate in presence or absence of triphenylphosphine

The bulk polymerization of acrylonitrile (AN) initiated by copper (II) nitrate, Cu(II), in the absence of light has been studied. The rate of the AN polymerization may be expressed in the Cu(II) concentration range from 5 × 10^?4 to 1 × 10^?1 mole 1.^?1 by the equation, R_p = k₅[Cu(II)]^0.68, where k₅ = K_AN[AN]/(1 + K_AN[AN]). From the spectrophotometric measurements the values of 0.70 l./mole and 0.08 l, mole were obtained for the equilibrium constant at 20 and 60°C, respectively, K_AN = [C]/[AN]-[Cu(II)], corresponding to the formation of the complex C from acrylonitrile and copper (II) nitrate. An addition of triphenylphosphine (C₆H₅)₃P into the polymerization system reduces R_p, and no polymerization takes place at all provided [(C₆H₅)₃P]/[Cu-(II)] ≧ 5. The retardation effect of (C₆H₅)₃P on the polymerization of AN initiated by Cu(II) is attributed to a competitive reaction of Cu(II) with (C₆H₅)₃P in which Cu(II) is reduced and the product of this reduction CuNO₃·2(C₆H₅)₃P is inactive with respect to the polymerization of AN.     

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.     

亚硝酸钠引发丙烯腈聚合的研究

研究了亚硝酸钠引发硝酸溶液中丙烯腈的聚合反应。测得表现聚合速度 Rp=Ae~(-10,800/RT)[AN]~2.2[NaNO_2]~(0.17-1.0)[HNO_3]~(1.0-0.67 丙烯腈-丙烯酸甲酯共聚合反应中竞聚率分别是γ_An=0.96,γ_MA=1.17,表明聚合反应是按自由基机理进行。 根据聚合动力学和红外光谱分析,认为以亚硝酸钠引发硝酸溶液中丙烯腈的聚合反应与电解或金属溶蚀过程中的次级引发相同。     

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.     

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.     

Vinyl Polymerization Initiated by Ceric Ion–Ethyl Cellosolve Redox System in Aqueous Nitric Acid

Abstract

Polymerizations of methyl methacrylate (MMA) and acrylonitrile (AN) were carried out in aqueous nitric acid at 30°C with the redox initiator system ammonium ceric nitrate-ethyl cellosolve (EC). A short induction period was observed as well as the attainment of a limiting conversion for polymerization reactions. The consumption of ceric ion was first order with respect to Ce(IV) concentration in the concentration range (0.2–0.4) × 10^?2 M, and the points at higher and lower concentrations show deviations from a linear fit. The plots of the inverse of pseudo-first-order rate constant for ceric ion consumption, (k ¹)^?1 vs [EC]^?1, gave straight lines for both the monomer systems with nonzero intercepts supporting complex formation between Ce(IV) and EC. The rate of polymerization increases regularly with [Ce(IV)] up to 0.003 M, yielding an order of 0.41, then falls to 0.0055 M and again shows a rise at 0.00645 M for MMA polymerization. For AN polymerization, R _p shows a steep rise with [Ce(IV)] up to 0.001 M, and beyond this concentration R _p shows a regular increase with [Ce(IV)], yielding an order of 0.48. In the presence of constant [NO^? ₃], MMA and AN polymerizations yield orders of 0.36 and 0.58 for [Ce(IV)] variation, respectively. The rates of polymerization increased with an increase in EC and monomer concentrations: only at a higher concentration of EC (0.5 M) was a steep fall in R _p observed for both monomer systems. The orders with respect to EC and monomer for MMA polymerization were 0.19 and 1.6, respectively. The orders with respect to EC and monomer for AN polymerization were 0.2 and 1.5, respectively. A kinetic scheme involving oxidation of EC by Ce(IV) via complex formation, whose decomposition gives rise to a primary radical, initiation, propagation, and termination of the polymeric radicals by biomolecular interaction is proposed. An oxidative termination of primary radicals by Ce(IV) is also included.     

Tetraphenylethane iniferters. II. Toluene diisocyanate-based polyurethane iniferter for “living” radical polymerization of acrylonitrile

A novel polyurethane iniferter, synthesized from equal moles of toluene diisocyanate and 1,1,2,2-tetraphenyl-1,2-ethanediol, was used to polymerize acrylonitrile to assess whether it proceeded via a “living” radical polymerization mechanism. From the kinetic results, the rate of polymerization could be expressed as R_pα[BPT]^0.96[AN]^1.64. The increase of number-average molecular weight with increase of both conversion and polymerization time, the bimodal molecular weight distribution in gel permeation chromatography and the increase of molecular weight in the post-polymerization of polyacrylonitrile confirm that the present tetraphenylethane-based polyurethane iniferter follows a “living” radical polymerization mechanism. © 1996 John Wiley & Sons, Inc.     

笼形聚羧酸钒(Ⅳ)—硫脲体系引发丙烯腈聚合动力学

研究了笼形聚羧酸钒(PV)-硫脲(TU)体系在硝酸溶液中引发丙烯腈(AN)聚合动力学。表观聚合速度(R_p)是 R_p=9.7×10~5e~(-10500)/RT[AN]~1.0[PV]~0.50[TU]~0.76[HNO_3]~1.5聚合诱导期(τ)随反应条件而变化,聚合温度越高,引发种浓度越大,聚合诱导期越短,但与单体浓度的变化无关。 1/τ=4.6×10~(12)e~(-13500)/RT[AN]~0[PV][TU]~(-3/2)[HNO_3]~3=K_τ·R_i聚合物分子量随单体浓度增大而提高,但随聚合温度及引发种浓度增大而下降,即 笼形聚羧酸钒—硫脲体系引发丙烯腈聚合的动力学参数和引发机理与杨梅型聚羧酸钒—硫脲体系在相同的条件下引发聚合的行为有明显的区别,认为是和两种树脂大分子链的空间结构所引起的传质阻力有关。     

Fullerene as radical inhibitor in polymerization of acrylonitrile initiated by arsonium ylide

Kinetics of polymerization of acrylonitrile (AN) in presence of fullerene (C₆₀) has been studied using p-acetyl benzylidine triphenyl arsonium ylide as initiator in dioxane at 60 ± 0.1°C under the blanket of nitrogen. The rate of polymerization (R _p ) at low concentration of fullerene may be represented as R _p ?? [Ylide]^0.5[AN]^1.0 [Full]^?0.6, indicating inhibition effect of fullerene on the polymerization. The energy of activation for the polymerization was found to be 71.5 ± 0.5 kJ mol^?1. Fourier transform infrared spectroscopic analysis (FTIR) confirmed the insertion of fullerene in to the final polymer. The mechanism for the polymerization has also been proposed.     

电荷转移聚合研究——三苯基磷引发丙烯腈光聚合

研究了三苯基磷(TPP)引发丙烯腈(AN)光聚合。测定了光聚合速率 R_p与单体浓度、引发剂浓度的关系为:R_p=K[AN]~(1.49)[TPP]~(0.47)以及光聚合反应活化能E_α=6.16千卡/摩尔,从激发态电荷转移机制,讨论了引发聚合机理。     

DEPENDENCE OF ACRYLONITRILE POLYMERIZATION KINETICS ON THE COMPOSITION OF POLYAMIDOXIME-THIOUREA SYSTEM

The polymerization of acrylonitrile (AN) initiated by polypropylene based-polyamidoxime (PPAO)-thiourea (TU) system was investigated at [TU]/[PPAO]>0.5 molar ratio. It shows that the variation of the concentrations of PPAO, thiourea and nitric acid does not exert an observable influence on the reaction rate. The overall rate of polymerization (R_p) isR_p = 2.07e~(-7,800/RT)[ AN]~(2.0)The zero order dependence on PPAO and thiourea concentrations and the lowest value of the collision frequence factor were considered to be a feature of the primary radical termination.     

含胺基功能性单体的聚合研究——ⅫⅠ.丙烯腈在N-丙烯酰-N′-苯基哌嗪及其聚合物作为增感剂下的光聚合

The photopolymerization of AN by using N-acryloyl-N'-phenylpiperazine (APP) and N-methacryloyl-N'-phenylpiperazine (MPP) as sensitizers under UV irradiation has been investigated. The corresponding polymerization kinetic equations are as follows:Rp [APP]^0.81[AN]^0.61 R_p [MPP]^0.48[AN]^0.77 R_p [P(APP)]^0.53[AN]^0.78 From the fluorescent analysis, it was confirmed that APP, MPP and P(APP) not only initiated the polymerization of AN but also entered into the chains of AN polymer. The photopolymerization mechanism for exciplex formation of AN with above sensitizers was proposed.     

Polymerization of Methyl Methacrylate with Bis(Cyclopentadienyl)Titanium Dichloride in a Water-Methanol Mixture: Formation of Tetrahydrofuran-Insoluble Polymer

Abstract

Methyl methacrylate (MMA) was found to be effectively polymerized with bis(cyclopentadienyl)titanium dichloride (CP₂TiCl₂) in a water-methanol mixture (1:1, v/v). The polymerization proceeded heterogeneously because the resulting poly(MMA) was insoluble in the system. The rate (R _p) of the heterogenous polymerization was apparently expressed by R _p = k[Cp₂TiCl₂]²[MMA]^2˙5 (at 40°C). The resulting poly(MMA) was observed to consist of tetrahydrofuran (THF)-soluble and insoluble parts. In contrast with the usual radical poly(MMA), the THF-insoluble part was soluble in benzene, toluene, and chloroform but insoluble in polar solvents such as ethyl acetate, acetone, acetonitrile, dimethylformamide, and dimethylsulfoxide. The polymerization was found to be profoundly accelerated by irradiation with a fluorescent room lamp (15 W). The results of copolymerization of MMA and acrylonitrile indicated that the present polymerization proceeds through a radical mechanism.