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.     

Vinyl Polymerization. 274. Polymerization of Acrylonitrile Initiated by the System Tetramethyl Tetrazene and Co(II) Chloride

Abstract

The binary system of tetramethyl tetrazene (TMT) and Co(II) chloride was used as initiator of acrylonitrile (AN) in dimethylformamide. The initial rate of polymerization (Rp) was found to be expressed by Rp = k[TMT]^0.62[Co(II) chloride]^0.57 [AN]^2.00

The polymerization was confirmed to proceed via a radical mechanism. The over-all activation energy for the polymerization was estimated as 15.1 kcal/mole. On the basis of these results and the product analysis of the reaction between the catalyst components in the absence of monomer, the initiation mechanism of the polymerization is discussed.     

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。     

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 Acrylonitrile Initiated by 1,4-Dimethyl-1,4-bis(p-nitrophenyl)-2-tetrazene

The polymerization of acrylonitrile (AN) initiated by 1,4-dimethyl-1,4-bis(p-nitrophenyl)-2-tetrazene (Ie) was studied in dimethylformamide (DMF) at high temperature. The polymerization proceeds by a radical mechanism. The rate of polymerization is proportional to [Ie]^0.64 and [AN]^1.36. The overall activation energy for the polymerization is 21.5 kcal/mole within the temperature range of 115-130°C. The chain transfer of Ie was also undertaken over the temperature range of 120-135°C. The activation parameters for the decomposition of Ie at 120°C are k_d = 2.78 × 10^?6 sec^?1, ΔH^? = 40.8 kcal/mole, and ΔS^? = 19.5 cal/mole-deg, respectively.     

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。     

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.     

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.     

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.     

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.     

Vinyl polymerization. 275. Polymerization of vinyl monomers photosensitized by tetramethyltetrazene

A study of the photopolymerization of vinyl monomers in the presence of tetramethyltetrazene (TMT) was made. TMT was found to act as an effective sensitizer. In the photopolymerization of vinyl monomers such as methyl methacrylate or styrene the rate of polymerization was expressed by the equation: R_p = k[TMT]^1/2[monomer]. The chain-transfer constant of TMT under ultraviolet irradiation was estimated to be 3.8 × 10^?2 for the above monomers. A linear correlation was found to exist between the reactivity of dimethylamino radical toward the vinyl monomers and e values for the corresponding monomers.     

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.     

Electro-initiated polymerization of acrylonitrile in aqueous acetic acid containing Mn(OAc)2·4H2O and CNCH2COOH

The electro-initiated polymerization of acrylonitrile initiated by the anodic oxidation of an aqueous acid solution (80% HOAc + 20% H₂O) containing Mn(OAc)₂ · 4H₂O/CNCH₂COOH has been investigated in the 30–40°C temperature range. The kinetics and mechanism of the process has been investigated as a function of variables and a suitable mechanism proposed. From the experimental observations the rate of polymerization is seen to be proportional to [An]^1.5I^0.5[Mn⁺²]^0.5 and [CAA]^0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of [CAA]^0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of CAA at high concentration. The average degrees of polymerization (P _n) increases with increasing AN and decreasing [CAA], [Mn⁺²] and applied current, I. The initiation is due to the anodic oxidation of Mn⁺²–CNCH₂COOH complex. Both the initiation of polymerization by the primary radical, viz., CN? C?? COOH as well as the oxidation of the primary radical at the electrode are equally significant reactions and neither can be neglected in comparison with the other. Predominant mutual termination accounts for all the observed data.     

"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.     

γ-Radiation-Initiated Polymerization of Acrylonitrile in Aqueous Solution and in Emulsion

The γ-radiation-initiated polymerization of acrylonitrile (AN) at 25[ddot] C has been studied, both in aqueous solution and in emulsion, at dose rates between 70 and 175 krad/hr. The effect of added emulsifier, sodium lauryl sulfate (SLS), on reaction rates, R_p, and on polymer molecular weight, M_n, has been investigated. G (monomer polymerized) values ranged from 7,500 in aqueous solution to 20,000 in bulk to 45,000 in emulsion, all based on the total energy absorbed. In the aqueous solution polymerization, where R_p is approximately first order in initial monomer concentration over the range 0.15 ± [AN]_o ± 1.06 moles/liter, addition of SLS increases R_p but does not influence the order of the reaction with respect to [AN]_o. In the emulsion system at 70 krad/hr and at a phase volume ratio AN/H₂O of 1/2, (PR = 1/2), R_p varies as [SLS]^0.1 over the concentration range 0.01 ± [SLS] ± 2.5± wt/vol of aqueous phase. At the same PR value, and at 80 krad/hr, M_n of the polymer (measured by viscometry in dimethylformamide solution) is effectively independent of [SLS] in the range of 0.01 ± [SLS] ± 10± wt/vol of aqueous phase. Initial R_p values are either independent of PR in the range 1/3 ± PR ± 1/1 or exhibit an insensitive and unsystematic dependence thereon. Based on measurements at 70 and at 175 krad/hr, the intensity exponent of R_p at PR = 1/2 is approximately 0.4.     

Effects of macromolecular matrix on the process of radical polymerization of ionizable monomers

Radical polymerization of methacrylic acid (MAA) and acrylic acid (AA) in the presence of a positively charged macromolecular matrix was studied. In the presence of a matrix, the rates of polymerization were remarkably increased, especially in high pH region. This suggests that electrostatic interaction between the macromolecular matrix and the growing chains and/or the monomer molecules plays an important role in the process of polymerization reaction. The kinetic orders were greatly influenced by the relative matrix concentration (PC) as follows: for (PC)₀ > [M]₀, R_p = k[M]^0.9 [PC]_0.3 [I]^0.8≤ [M]₀ R_p = k[M]^0.3[PC]⁰[I]^0,8 where [M] and [I] are monomer and initiator concentration, respectively, and k is a constant. The mechanism of the interaction of matrix with monomer and/or growing chains in the process of the propagation is discussed. The complex formed in the matrix polymerization could be easily made into fiber by spinning.     

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.     

1-(Bromoacetyl)pyrene,a novel photoinitiator for the copolymerization of styrene and acrylonitrile

A comparative study on photoinitiated solution copolymerization of Styrene (Sty), with acrylonitrile (AN) using pyrene, 1-acetylpyrene, and 1-(bromoacetyl)pyrene (BrPy) as initiators, showed that the introduction of a chromophoric moiety, bromoacetyl (–COCH₂Br), significantly increased the photoinitiating ability of pyrene. The kinetics and mechanism of copolymerization of Sty with AN (Sty–co–AN) using BrPy as photoinitiator has been studied in detail. The kinetic data, inhibiting effect of benzoquinone, and electron spin resonance (ESR) studies suggest that the polymerization proceeds via a free radical mechanism. The system followed non-ideal kinetics (R _p α[BrPy]^0.7[Sty]^1.09[AN]^1.01) and degradative solvent transfer reasonably explained these kinetic non-idealities. The co-monomer reactivity ratios calculated by using the Finemann–Ross and Kelen–Tudos models were r ₁ (Sty) = 0.39 and r ₂ (AN) = 0.05. The reactivity ratios strongly indicate that the two monomers enter in almost alternating arrangement along the copolymer chain.     

KINETICS OF POLYMERIZATION OF ACRYLONITRILE INITIATED BY VANADIUM(V)-THIOUREA REDOX SYSTEM

The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V~(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2~+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.     

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.