Calculation of Alfrey–Price Q–e Values from 13C-NMR Data

A multiple-correlation analysis program was used to generate equations relating the Alfrey–Price Q and e values of vinyl monomers to the ¹³C-NMR absorption frequencies of the α- and β-carbon atoms of the monomers. Separate equations for the calculation of Q and e values of styrenes, chlorinated olefins, acrylates, methacrylates, vinyl ethers, and esters, nitrogen containing monomers, allyl compounds, and miscellaneous olefins were developed. The correlation coefficients of most of these equations were greater than 0.99 and permit accurate calculation of the Q and e values. The Q and e values so calculated may then be used to obtain estimates of the reactivity ratios in copolymerizations prior to actually performing the experiments. Attempts to develop a single Q value equation and a single e value equation for 63 vinyl monomers of the above classes resulted in relations having correlation coefficients of 0.63 and 0.81, respectively, too low to permit sufficiently accurate calculation of the Q and e values.     

Synthesis and polymerization of heteroaromatic vinyl monomers

Methods of preparing new monomers, 2-vinyl and 2-isopropenyloxazoles and 2-isopropenyl-1,3,4-oxadiazoles are described. New methods were developed to synthesize monomers containing an isoxazole or a thiazole ring. Radical homopolymerization and copolymerization with styrene of these monomers were carried out by using AIBN as an initiator. Monomer reactivity ratios r₁, r₂ and Alfrey-Price Q–e values were determined by the Fineman-Ross and the Mayo-Lewis methods. The localization energy of the β-carbon was calculated by a HITAC-5020 computer, and the monomer reactivity is discussed in terms of L_β.     

Calculation of Reactivity Ratios and Sequence Distributions in Copolymers from Monomers 13C-NMR Data

A screening procedure has been developed to predict the average sequence distribution in vinyl copolymers from monomer ¹³C-NMR data. The ¹³C-NMR absorption frequencies of the carbon atoms of the polymerizable double bond are used to calculate the Alfrey-Price Q and e values as previously described by Borchardt and Dalrymple. These, in turn, are used to calculate the monomer reactivity ratios. Reactivity ratios for 54 copolymerizations were calculated by this procedure and compared to literature values. The copolymer sequence distribution may then be determined by means of a computer program written by Harwood. The sequence distribution in copolymers of methacrylic acid and dimethyl-aminoethyl methacrylate, acrylonitrile and methyl methacrylate, 1,1-dichloroethylene and methacrylonitrile, ethyl acrylate and n-butyl methacrylate, and acrylamide and sodium 2-acrylamido-2-methylpropane sulfonate were calculated from reactivity ratios derived from ¹³C-NMR data and compared to literature values. This procedure may be used to calculate the reactivity ratios from ¹³C-NMR spectra of monomers for which no Q and e values are known. By this method the average sequence distribution of such monomers in copolymers may be predicted, significantly reducing the number of copolymers to be synthesized and tested for use in various applications.     

Change in the reactivity of N-vinylsuccinimide after complexation with dimethyl sulfoxide

The influence of dimethyl sulfoxide on the copolymerization kinetics and the reactivity parameters of N-vinylsuccinimide was studied. It was shown that, owing to the complexation of monomer molecules with dimethyl sulfoxide molecules, the relative activities of monomers are changed. The electron structures of N-vinylsuccinimide and dimethyl sulfoxide molecules and the molecule geometry was considered, and a complexation mechanism was proposed. The Alfrey–Price Q-e parameters of N-vinylsuccinimide during the complexation were analyzed. The causes of the change in the reactivity of monomer were revealed.     

Synthesis of a Diverse Library of N,N-Dimethylamino Containing Monomers Appropriate as Lipid Head Groups

We report on the synthesis of a diverse library of N,N-dimethylamino containing monomers. Subjecting these monomers to Chabrier reaction conditions would yield lipids with polymerizable head groups. This library of lipid head groups is equipped with arms of various lengths containing reduction-oxidation polymerizable groups at the terminus.     

Synthesis and polymerization of N-[1-(1-substituted-2-oxopropyl)]acrylamides and -methacrylamides. copolymerization of these monomers with styrene and substituent effects

The synthesis and polymerization of N-[1-(1-substituted-2-oxopropyl)]acrylamides and -methacrylamides are described. Seven new monomers were prepared by two kinds of synthetic procedure. The polymerization of these monomers was carried out. Monomer reactivity ratios in the polymerization of these monomers with styrene were determined and the Alfrey-Price Q and e values calculated. The effects of substituents on the reactivities in copolymerization were observed, and an interpretation of the results is given.     

Copolymerization of ethylene with a homologous series of vinyl esters

The effect of the alkyl group on the relative reactivity of a homologous series of vinyl esters (2) has been studied with ethylene (1) as reference monomer, tert-butyl alcohol as solvent, at 62°C and 35 kg/cm². The experimental method was based on frequent measurement of the monomer feed composition throughout the copolymerization reaction by means of quantitative gas-chromatographic analysis. Highly accurate monomer reactivity ratios were estimated in a statistically justified manner by a nonlinear least-squares method applied to the integrated copolymer equation. The reactivity of the vinyl ester monomers towards an ethylene radical increased with decreasing electron-with-drawing ability of the ester group. All vinyl ester radicals considered turned out to have the same preference for their own monomer over ethylene (constant r₂ = 1.50). Reactivity ratios are discussed in terms of the Q–e scheme and the Taft relation. It appeared that chiefly polar factors contribute to the observed relative reactivity, while probably resonance stabilization only plays a minor part. Steric hindrance seems to impair monomer reactivity, only from vinyl pivalate on. Relative reactivities of the vinyl esters are compared with literature values, where other reference monomers have been used.     

Ferrocene-containing polymers. II. Radiation-induced copolymerizations of ferrocenylmethyl methacrylate with styrene,methyl methacrylate,and ethyl acrylate

Ferrocenylmethyl methacrylate (FMMA) was copolymerized with styrene (St), methyl methacrylate (MMA), and ethyl acrylate (EA) in benzene solution at 25°C by γ radiation. The reactions proceeded by a free radical mechanism, and monomer reactivity ratios were derived by the Tidwell–Mortimer method for St(M₁)–FMMA(M₂), r₁ = 0.35 and r₂ = 0.46; for MMA(M₁–FMMA)(M₂), r₁ = 0.85 and r₂ = 1.36; for EA(M₁)–FMMA(M₂), r₁ = 0.36 and r₂ = 3.03. The Q and e values of FMMA determined from copolymerization with St were 0.97 and 0.55, respectively. Terpolymerization of a MMA–FMMA–EA system based on the Alfrey–Goldfinger equations was studied. This is a typical terpolymerization system in which reactivities of the monomers obey the Q–e scheme. Comparing the results obtained here with those previously reported for other monomers, we concluded that FMMA is one of the most highly reactive monomers among alkyl methacrylates.     

Copolymerization of new pyrazolone-containing monomers with certain vinyl comonomers

The polymerization ability of two new pyrazolone-containing monomers—3-methyl-1-phenyl-4-crotonoyl-pyrazolone-5 ( Cr ) and 3-methyl-1-phenyl-4-(3′-phenyl-acryloyl) pyrazolone-5 ( Cy )—was investigated. The monomers were obtained by acylation of 3-methyl-1-phenyl-pyrazolone-5 with crotonyl chloride or cinnamoyl chloride, respectively. It was established that the two monomers do not homopolymerize either under the action of ionic and radical initiators nor with γ-rays (doses between 2 and 10 MRad). In contrast to this, the two monomers copolymerize with other vinyl comonomers. Copolymers of Cr and Cy with methacrylic acid (MAA), methyl methacrylate (MMA), and Styrene (St) were synthesized by radical copolymerization. The molecular weights of the polymer products obtained were in the 10,000–65,000 range. It was established that the molecular weight characteristics of the copolymers were affected by the concentration of the pyrazolone-containing monomer and by the chemical nature of the solvent used. The copolymerization of Cr and Cy with MAA was investigated in detail in order to evaluate the relative activity of the new monomers during copolymerization. The reactivity ratios (r) were calculated by three different methods with good agreement. The values obtained for the monomer pairs are: r_MAA = 0.61 ± 0.01, r_Cr = 0.04 ± 0.01; r_MAA = 0.64 ± 0.05, r_Cy = 0.02 ± 0.02. The Q/e values for Cr and Cy were determined using the reactivity ratios of both monomers.     

Molecular orbital study of the Q–e scheme in free radical copolymerization

Molecular orbital calculations were used to study free radical polymerization. Calculations show that the monomer is activated during the reaction and the pi bond becomes a diradical. The radical on the carbon that is about to form the new bond is called the e radical in this article. The other is the Q radical. For different monomers it is shown indirectly that changes in the energies of formation of the Q and e radicals are related to changes in the Q and e terms in the empirical Q–e scheme of Alfrey and Price. The polar effect in the Q–e scheme involves the e-radical, unpaired electron density. Specifically, the Q–e sum (e_x + e_y) is correlated with the e radical spin density. Also the e term is correlated with the electron density on the unsubstituted carbon of the monomer. The relationship of the Q radical to the adjacent substituent is shown by correlating ln Q values with the energy of addition of a hydrogen atom to a monomer. These relationships give theoretical meaning to the Q–e terms and allow calculation of Q and e values from molecular orbital properties for small monomers.     

A comparison of the absolute reactivity of vinyl monomers. I. Kinetic studies on radical polymerization of vinyl monomers initiated by a Mn3+–diglycolic acid redox system

The kinetics of polymerization of acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) initiated by the redox system Mn³⁺–diglycolic acid (DGA) was studied. All three systems followed the same mechanism; namely, initiation by an organic free radical arising from the oxidation of diglycolic acid and termination by the interaction of polymer radicals with Mn³⁺ ion. The rate coefficients k_i/k₀ and k_p/k_t were related to monomer and polymer radical reactivity, respectively. An inverse relation between monomer and polymer radical reactivity was observed. Monomers with higher Q values gave higher k_i/k₀ values but lower k_p/k_t values. The e values of the monomers were important in determining the reactivities of monomers with nearly the same Q values.     

Synthesis,characterization, and polymerization of propenyl ether analogues

A series of aromatic monomers bearing cationically polymerizable propenyl groups were prepared and characterized using the readily available starting materials: isoeugenol and o-allyl phenol. Monomers with both propenyl and vinyl ether functional groups were also synthesized by the reaction of these starting materials with chloroethyl vinyl ether. The reactivity of the resulting monomers in photoinitiated cationic polymerization was studied using differential scanning photocalorimetry and photogel point measurements. Their thermal properties were determined using thermogravimetric analysis. © 1994 John Wiley & Sons, Inc.     

Copolymerization behavior of vinylimidazolium salts

Copolymerization studies of cationic monomers have been reported in the literature to yield wide variations in reactivity ratios and Q–e values, depending on the comonomer and the nature of the solvent. In this work are presented the copolymerization characteristics of a variety of vinylimidazolium salts in both water and ethanol solution. From these studies, the effect of solvent polarity, of substitution at the imidazolium 2-position, of the type of counterion, and of the hydrophilic–hydrophobic character of the monomeric salts could be ascertained. The results of the study are consistent with other related investigations, in that solvent polarity and comonomer both strongly affected copolymerization.     

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.     

N-vinylthiopyrrolidinone

The polymerization reactivity of N-vinylthipyrrolidinone is described. This monomer readily homopolymerizes and forms copolymers with a wide variety of vinyl monomers. Reactivity ratios in the copolymerization of N-vinylthiopyrrolidinone with styrene and methyl methacrylate are reported and the Alfrey-Price Q and e values calculated. These results indicate the high copolymerization reactivity of this monomer in comparison with the oxo-analog, N-vinylpyrrolidinone. Some of the results are in conflict with previously reported data.     

Copolymérisations radicalaires sous haute pression. Influence de la pression sur les rapports de réactivité

The pressure effect upon the reactivity of the radicals in copolymerizations can be important. The present work reports the pressure dependence of the reactivity ratios for some radical copolymerizations involving monomers of various polarities and proposes an interpretation concerning their variations with pressure based upon the Q—e scheme (or Alfrey–Price scheme). The direction as well as the magnitude of the pressure effect can thus be predicted.     

Solvent effects on the copolymerization kinetics of ionic (AMPS) and non-ionic (HEAm) acrylamide derivatives

The free-radical copolymerization of two N-substituted acrylamide monomers, the ionic AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid) and the non-ionic HEAm (2-hydroxyethylacrylamide) is presented. Despite bearing similar polymerizable functionalities, HEAm is more reactive toward free-radical addition than AMPS in water. In a mixed aqueous solvent containing salt, (0.5 M LiNO₃, 50 wt%) and ethanol (50 wt%), the reactivity ratio was found to be r_AMPS = 0.53 and r_HEAm = 1.06 indicating that copolymers with a nearly random distribution of sulfonic and hydroxy functionalities can be prepared.     

Synthesis and polymerization of various vinyl-type monomers containing the pyrrole ring

Vinyl-type monomers containing the pyrrole ring, such as 2-vinylpyrrole (2-VPyrr), N-(pyrrol-2-yl)methylacrylamide (PMA), N-methyl, N-(pyrrol-2-yl)methylacrylamide (MPMA), 2-allylpyrrole (2-AP), β-(pyrrol-1-yl)ethyl vinyl ether (PEVE), 2-diallyl-aminomethylpyrrole (DAMP), and 3-(2-pyrrolylmethyleneimino)propene-1 (PIP) were synthesized by various reactions involving characteristic properties of the pyrrole ring. Radical homopolymerizations and copolymerizations of these monomers were studied. In the homopolymerization of conjugated monomers such as 2-VPyrr and PMA, chain transfer to the pyrrole-containing monomer was remarkable but not degradative. The copolymerization parameters, that is, the values of r₁, r₂, Q₁, and e₁ of 2-VPyrr, were determined to be 0.066, 0.69, 5.53, and ?1.36, respectively in the copolymerization of 2-VPyrr (M₁) with MMA (M₂). The Q and e values of the monomers containing a heteroaromatic ring such as 2-vinylpyrrole, 2-vinylfuran, and 2-vinylthiophene were evaluated by the molecular orbital theory. The e value of PMA was found to be negative (?0.64) in the copolymerization with styrene, although e for acrylamide derivatives is generally positive. This may be explained by the intermolecular hydrogen bonding between the carbonyl group and NH group of PMA. That is, attraction or polarization of π-electrons in the vinyl group of PMA is weakened by such hydrogen bonding. From the results of copolymerization of 2-AP with various comonomers, the comonomers could be classified into three categories: class a monomers, in which both Q and e values are largely positive, can copolymerize with 2-AP; class b monomers, having small e values, homopolymerize and can not copolymerize with 2-AP; class c monomers, in which both Q and e values are small. The Q and e values of the comonomer must be largely positive in order to permit copolymerization with an allyl-type monomer.     

Comparative study of the absolute reactivity of vinyl monomers: Kinetics of polymerization of vinyl monomers initiated by Mn3+–thiodiglycolic acid redox system

The kinetics and mechanism of polymerization of methacrylic acid (MAA) and ethyl acrylate (EA) initiated by the redox system, Mn³⁺–thiodiglycolic acid (TDGA) were investigated in the 15–35°C temperature range. The polymerization kinetics of both the monomers followed the same mechanism, viz., initiation by primary radical and termination by Mn³⁺–thiodiglycolic acid complex. The rate coefficients k_i/k₀ and k_p/k_t were related to the monomer reactivity and polymer radical reactivity, respectively. It was observed that both monomer reactivity and polymer radical reactivity followed the same order, viz., EA > MAA. The polymer radical reactivity varied inversely with the Q values of the monomers.