Vinyl polymerization. 120. Mutual copolymerization of p-substituted styrenes through radical mechanism

The radical mutual copolymerization of p-substituted styrenes, such as p-methoxy-, p-chloro-, p-bromo-, p-cyanostyrene, and styrene was carried out with one another at 30°C. in the dark. As initiator, azobisisobutyronitrile was used. The plots of the copolymerization rates against HAMMETT 's σ values showed no linear relationships and the concave curves were obtained therefrom. The relative reactivities of p-substituted styrenes with a definite p-substituted polystyryl radical, which were shown by the reciprocal of monomer reactivity ratio r₁, were plotted against σ values and concave curves were also obtained. The relative reactivities of p-substituted polystyryl radicals with p-substituted styrene were calculated from the ratios r₂ and the propagation rate constants in homopolymerization. the plots of them against σ values gave straight lines with different ρ values, according to the polarity of substituents. These results suggest that polar structures in transition state affected markedly the copolymerization rates. The effect of substituents on resonance stabilization was also quantitatively estimated.     

Vinyl polymerization. 238. Polymerization of acrylonitrile initiated by tetramethyl tetrazene and benzyl chloride

A study of the polymerization of acrylonitrile (AN) initiated by tetramethyl tetrazene (TMT) and benzyl chloride (BC) system was made. It was found that the polymerization proceeds through a radical mechanism. The initial rate of polymerization, R_p, followed the equation: From the results the initiation mechanism was discussed.     

Vinyl polymerization. 221. Polymerization of methyl methacrylate in the presence of cellulose triacetate

A kinetic study on the polymerization of methyl methacrylate (MMA) was made in the presence of cellulose triacetate (CTA) and water. In this case, water was found to be not necessary for the initiation of polymerization. The reaction proceeds by a radical mechanism, and the rate of polymerization can be expressed by the following equation: The overall activation energy for the polymerization was estimated as 7.9 kcal/mole. The grafting efficiency of polymethyl methacrylate (PMMA) to CTA decreased with increase in polymerization temperature. The molecular weight of the extracted PMMA decreased also slightly with increase in polymerization temperature and was independent on the concentration of CTA. These results suggest that the molecular weight of PMMA is mainly affected by the transfer of growing radical to monomer molecule.     

Vinyl polymerization. 194. Polymerization of methyl methacrylate in the presence of partially hydrolyzed polyvinyl acetate and water

The polymerization of methyl methacrylate was carried out without radical initiators,in the presence of partially hydrolyzed polyvinyl acetates and water. It was found that high molecular polyvinyl acetate and polyvinyl alcohol could not initiate the polymerization of inethyl methacrylate in the presence of water, while partially hydrolyzed polyvinyl acetates and formalized polyvinyl alcohol could initiate the polymerization. The results were discussed in connection with those of our series of studies.     

Vinyl polymerization. 198. A kinetic study on the polymerization of acrylonitrile initiated by tetramethyl tetrazene in presence and absence of acetic anhydride

The polymerization of acrylonitrile (AN) was carried out in dimethyl formamide. The initiator was tetramethyl tetrazene (TMT) or a mixture of TMT and acetic anhydride (AA). The polymerization proceeded through a radical mechanism. The rate equations are: Adopting the value of (Ep ? 1/2 E_t) as ca. 5 kcal/mole, the activation energies for initiation, E_i, were estimated as ca. 40 kcal/mole for TMT and as ca. 15 kcal/mole for TMT/AA. TMT/benyl chloride or TMT/benzoic anhydride systems initiate a polymerization of AN more easily than TMT alone.     

Vinyl polymerization 176.. Vinyl polymerization in the presence of macromolecules,water and carbon tetrachloride: A macromolecule as a part of a complex initiator

Polymerization of vinyl monomers was studied in presence of cellulose (or silk), water, and carbon tetrachloride, and in absence of the usual radical initiators. It was found that the rate of polymerization of methyl methacrylate was strongly accelerated by the carbon tetrachloride; the efficiency of grafting, however, decreased markedly with increasing amount of carbon tetrachloride. A polymerization mechanism is proposed in which a macromolecule is part of a complex initiator and perhaps plays a role as a polymerization matrix.     

Vinyl polymerization. 280. Anionic polymerization of acryloyl- and methacryloyl verdazyls

1.5-Diphenyl-3-(p-methacryloyloxymethylphenyl) verdazyl (I), 1.5-diphenyl-3-(p-methacryloyloxyphenyl) verdazyl (II), and 1.5-diphenyl-3-(p-acryloyloxymethylphenyl) verdazyl (III) were synthesized and anionically polymerized with n-butylmagnesium bromide or sodium naphthalene as an initiator to dark green polymers of a molecular weight of about 2300. III was polymerized with a catalytic amount of initiator, while I needed more initiator than the molar equivalent of the monomers suggesting the formation of intermediate metal salts of monomers and subsequent polymerization of the salts. More reactive double bond of III polymerized directly without the formation of the salt between stable free radical and organometallic compounds. Polymeric verdazyls contained up to 68% stable free radical.     

Vinyl polymerization by metal complexes, 21. Initiation mechanism of vinyl polymerization by amine-copper(ii) complexes in the presence of carbon tetrachloride

In order to elucidate the initiation mechanism of the vinyl polymerization by amine-copper(II) complexes in aqueous solution, in the presence of carbon tetrachloride, the reaction of amine-copper(II) complexes with carbon tetrachloride was studied by ESR, visible spectroscopy, and the spin trapping method. The ESR signal of copper(II) disappeared during the reaction, suggesting the reduction of copper(II) to copper(I) in the initial step of the reaction. This reduction was also ascertained both by visible spectral changes and by the cuproin coloration method. The initiation mechanism is discussed based on these results and the information about the initiating free radical species by the spin trapping method.     

Vinyl polymerization, 311. Synthesis and polymerization of 2-bromoethoxyphenoxyphosphoryl methacrylate

2-Bromoethoxyphenoxyphosphoryl methacrylate ( 5 ) was synthesized by the reaction of 2-bromoethyl phenylchlorophosphonate ( 3 ) with silver methacrylate and then polymerized by a radical initiator. The resulting polymer was soluble in DMF, but insoluble in other organic solvents. The hydrolysis of the polymer with sulfuric acid led to the corresponding poly(methacrylic acid) with a molecular weight of M_n=4,4·10⁵ (P_n=5,1·10³). 5 was copolymerized with acrylonitrile and the monomer reactivity ratio was determined: r₁ = 2,20, r₂=0,27.     

Coordinative polymerization of p-substituted phenyl glycidyl ethers, 2

As a complementary study of a previous work about the influence of the electronic effects of p-substituted phenyl glycidyl ethers on the polymerization behaviour, a new series of monomers with electron-withdrawing groups was prepared, i.e., highly reactive p-functionalized poly(phenyl glycidyl ethers) were prepared. The polymerizations were carried out with four different aluminium-based coordinative initiators, (C₂H₅)₃Al/H₂O (mole ratio 1:0.6) (the Vandenberg catalyst), (C₂H₅)₃Al/CH₃COCH₂COCH₃/H₂O (mole ratio 1:1:0.5) (the Vandenberg chelate catalyst), [(CH₃)₂CHO]₂Al? O? Zn? O? Al[OCH(CH₃)₂]₂ (the Teyssié catalyst) and [(CH₃)₂CHO]₃Al/ZnCl₂ (the Price catalyst), all with different Lewis acid character. The influence of the electron withdrawing groups on the characteristics and conversion of polymers was studied. All polymers were characterized by nuclear magnetic resonance spectroscopy showing higher tacticities when the Price catalysts was used. In some cases the degree of conversion was low due to passivation effects which were studied in several experiments.     

Vinyl polymerization. 195. Effect of trace metals on the polymerization of methyl methacrylate the presence of macromolecules and water: Activation analysis of metals in cellulose and silk

The polymerization of methyl methacrylate was carried out in the presence of silk cellulose and water in order to study the effect of trace metals contained in the fibers the polymerization. It was found that ethylenediamine tetraacetic acid retarded the polymerization, and that the addition of trace metals to the reaction systems could not initiate or accelerate the polymerization. Activation analysis was also made for the fibers. From the results it was concluded that the polymerization was not caused by such trace metals previously present in the fibers, but initiated only by the system of fiber and water.     

Vinyl polymerization. 236. Inhibiting effect of verdazyl in radical polymerization; mechanism of inhibition reaction

Verdazyl, a new type of stable free radical, was found to inhibit effectively the radical polymerization of styrene and methyl methacrylate. Inhibition period measured by dilatomethry was proportional to the concentration of verdazyl. The reaction prodacts formed in the system such as N-benyl-verdazyl, N-2-(2-carbomethoxy)propyl-verdazyl and the deduced reaction product, leucoverdazyl, had no effect on the measurement of inhibition period. 2-(2-Cyano)propyl-verdazyl dissociates at temperatures over 40°C but does not interfere the determination of inhibition period at 30°C. The rate of initiation reaction and the ratio of rate constants, k²_p/2k_t, which were calculated from the consumption rate ofDPPH and from the relationship between polymerization rate and the degree of polymerization. The absorption of verdazyl, at 720 mμ enables to measure inhibition periods from the change of the intensity of the absorption. Polymerizations of vinyl chloride and acrylontrile were also inhibited by verdazyl. Determination of the inhibition period for vinyl acetate was difficult, because the time-conversion curves after the inhibition period were not linear. Polymeric verdazyl also inhibits the radical polymerization of Vinyl monomers.     

Coordinative polymerization of p-substituted phenyl glycidyl ethers, 1. Effect of electron-donating groups

A series of p-substituted glycidyl phenyl ethers

1 IUPAC nomenclature: 2,3-epoxypropyl phenyl ether.

with electron donor groups was prepared using a multistep synthetic method. These compounds were polymerized using four of the most common aluminium-based coordinative initiators, (C₂H₅)₃Al/H₂O (the Vandenberg catalyst), (C₂H₅)₃Al/CH₃COCH₂COCH₃/H₂O (the Vandenberg chelate catalyst), [(CH₃)₂CHO&]₂Al? O? Zn? O? Al[OCH(CH₃)₂]₂ (the Teyssié catalyst) and [(CH₃)₂CHO]₃AV/ZnCI₂ (the Price catalyst), all with different Lewis acid character. The influence of the electron-donor group on the characteristics and conversion was studied. Generally speaking, both the Vandenberg and the Teyssié catalysts yield mostly an insoluble polymer fraction, whereas the Price catalyst was shown to be the most stereoselective catalyst. Moreover, the Vandenberg chelate catalyst gave the highest molecular weight, the Price catalyst the lowest. Thermal characteristics of polymers were studied by means of differential thermal analysis to obtain glass transition temperatuures, melting temperatures and fusion enthalpies.     

Kinetics of polymerization of benzyl acrylate in bulk

The kinetics of polymerization of benzyl acrylate has been studied at 55, 60, and 65°C with azobisisobutyronitrile as initiator. The overall rate of polymerization, degree of polymerization, chain transfer due to monomer, and the ratio of propagation and termination constant were calculated. The overall activation energy, the difference between the activation energy of propagation and termination, and the frequency factor are also reported.     

Vinyl polymerization. 217. Vinyl compounds of nucleic acid basis. I. Synthesis of N-vinylthymine,and N-vinyladenine

The synthesis of N-vinyluracil, N-vinylthymine, and N-vinyladenine is described. The general procedure consists of the conversion of the corresponding nucleric acid bases to their N-hydroxyethyl compounds, followed by chlorination to the N-chloroethyl compounds and dehydrochlorination to the N-vinyl derivaties.     

Vinyl polymerization. 235. Free radicals in the polymerization of vinyl monomers initiated by GOMBERG's and its relatad reactions

Free radicals derived from the GOMBERG 's reaction of arylmethyl halides such as benzyldiphenylmethyl-, and tritylbromide and chloride, with silver powder or mercury can initiate the radical polymerization and copolymerization of styrene, methyl methacrylate, acrylonitrile, vinyl chloride, and vinyl acetate. The orders of initiating abilities of halides in the polymerization of styrene and methyl methacrylate were as follows; for bromides, benzyl- > diphenylmethyl- > trityl-, and for chlorides, diphenylmethyl- > benzyl- > trityl-, when silver was used as metal component, while the order for the both halides is diphenylmethyl- > benzyl- > trityl- with mercury. These results were understood by the competition of the reactivities of halides to metal with those of the derived radicals to monomer. The over-all polymerization rate of the system styrene/silver/benzyl bromide was proportional to monomer concentration, square root of halide concentration, and square root of the amount of added but insoluble silver powder. The radical-like composition curves of styrene-methyl methacrylate copolymers and the inhibition of polymerization by verdazyl, a stable free radical, show that these polymerization systems include radical propagation step. Hexaphenylethane and 1.1.2.2-tetraphenylethane were isolated from the reaction systems, trityl halide/silver and diphenylmethyl chloride/silver or mercury, respectively. Recombination products of verdazyl with diphenylmethyl radical and benzyl radical were also isolated, but not N-trityl-verdazyl. Tracer study with benzyl bromide-7?¹⁴C showed the incorporation of benzyl fragments in the obtained polymer.     

Vinyl chloride studies. II. Initiation and termination in the homogeneous polymerization of vinyl chloride

The polymerization of 4 and 5 molar vinyl chloride in chlorobenzene solution has been studied using 0.005 to 0.1 molar ¹⁴C labelled azoisobutyronitrile as initiator at temperatures of 30 and 40°C. The number of initiator fragments per polymer molecule increases with the rate of initiation and extrapolates to 1.15 at an infinite rate of initiation showing that 25% of mutual termination occurs by combination and 75% by disproportionation. Values found for the efficiency of initiation vary from about 70% at the lowest initiator concentration to 55% at the highest.     

Vinyl polymerization 270. Polymerization of methyl methacrylate initiated by azibenzil

The polymerization of methyl methacrylate initiated by azibenzil (AB) was studied kinetically. The initial rate of polymerization (R_p) was found to be expressed by the equation R_p = k[AB]^0.47[MMA]^0.97. The polymerization proceeded through a radical mechanism. The overall activation energy for the polymerization was estimated as 16.1 kcal/mole. Furthermore, the rate of decomposition of AB was measured in benzene and the following rate equation was obtained: k_d[sec^?1] = 5.75·10¹⁰ exp(-21.9 kcal/RT). From these results the initiation mechanism was discussed.     

Application of spin trapping technique to radical polymerization, 20. Vinyl polymerization initiated by triphenylboron

Triphenylboron was found to serve as an effective radical initiator for vinyl monomers without any participation of oxygen. The polymerization of methyl methacrylate (MMA) initiated by triphenylboron was studied kinetically in acetonitrile. The over-all activation energy of the polymerization was calculated to be 60,3 kJ/mol. The polymerization rate (R_p) can be expressed as follows: R_p = k (Triphenylboron)^0,9[MMA]^1,8. Spin trapping studies revealed formation of phenyl radicals by decomposition of triphenylboron in the absence of oxygen. Decomposition of triphenylboron in toluene yielded o-, m-, and p-methylbiphenyls, the isomer ratio of which was close to that observed in the decomposition of benzoyl peroxide in toluene. Furthermore, an ethanol solution of triphenylboron was found to give a very stable boron centered radical. From these findings, the initiation mechanism for the polymerization is proposed and discussed.