Monomer Reactivity Ratios R1 Research Articles

Polymerization and Copolymerization of N-(4-Carboxyphenyl)maleimide

Homopolymerization and copolymerization of N-(4-carboxyphenyl)maleimide (CPMI) were performed at 70°C in the presence of azobisisobutyronitrile (AIBN) as an initiator in tetrahydrofuran. The initial rate of polymerization was Rp=k[AIBN]0.65 [CPMI]2.4, where k is an over-all rate constant. The monomer reactivity ratios (r1, r2) in the polymerization of CPMI (M1) with styrene (ST, M2), or with methyl methacrylate (MMA, M2) and Alfrey-Price Q, e values were determined as r1=0.019, r2=0.23, Q1=0.67, e1=1.53 for the CPMI-ST system; r1=0.24, r2=1.08, Q1=1.09, e1=1.56 for the CPMI-MMA system.

Liquid Crystalline Polymers from Fumarates Containing Mesogenic Methoxyphenylazophenoxy Groups

Abstract Radical polymerization of three fumarates, ethyl 4-(4-methoxyphenylazo)phenyl fumarate (1), ethyl 6-[4-(4-methoxyphenylazo)phenoxy]hexyl fumarate (2), and ethyl 11-[4-(4-cyanophenoxycarbonyl)phenoxy]undecyl fumarate (3) was carried out in benzene. Monomers 2 and 3 polymerize to give nematic polyfumarates [poly(2), poly(3)], while monomer 1 gives no polymer. From the copolymerization of monomer 2 (M2) with styrene (M1) the monomer reactivity ratios r1 and r2 were found to be 0.60 and 0.06, respectively. The copolymerization of monomers 2 and 3 was also carried out in an attempt to obtain a guest-host system [poly(2/3)]. The rate of isomerization from trans- to cis-azobenzene was found to be 0.038 min−1 for poly(2/3).

Functionalized monomers, 2. Kinetics of radical polymerization of oxirane‐ and oxetane‐derivatives of styrene and copolymerization of 4‐vinylphenyloxirane with styrene

AbstractThe kinetics of radical polymerization of 4‐vinylphenyloxirane (1), 4‐vinylbenzyloxirane (2), and 2‐(4‐vinylphenyl)oxetane (3) initiated by 2,2′‐azoisobutyronitrile (AIBN) was studied. In the case of 1 the initial rate of polymerization was found to depend on the initiator and monomer concentrations as (rp)total ∝︁ [AIBN]0,5 · [M1]1,36. The higher order of the polymerization rate with respect to 1 was interpreted as due to a concurrent thermally initiated polymerization; the rate of the latter was found to depend on the monomer concentration squared. The value of the ratio propagation rate constant over square root of termination rate constant kp/kt1/2 = 2,8 · 10−2 dm3/2 · mol−1/2 · s−1/2 was determined from the measured dependences (rp)total = f[AIBN] and (rp)total = f([M1]), corrected for the rate of thermally initiated polymerization of 1. On the other hand, the kinetics of radical polymerization of 2 and 3 did not deviate from the standard scheme valid for radical polymerization; in both cases the observed reaction order with respect to initiator and monomer was 0,5 and 1, respectively. Radical copolymerization of 4‐vinylphenyloxirane (M1) with styrene (M2) was characterized by monomer reactivity ratios r1 = 1,06 and r2 = 0,78, respectively, corresponding to the Q, e‐scheme values Q = 0,9 and e = −0,36 for monomer 1.

Synthesis and Polymerization of Optically Active Mono-I-Menthyl Itaconate

Abstract Optically active mono-l-menthyl itaconate (MMI) was prepared from ita-conic acid and l-menthol. MMI was polymerized in bulk at 80°C to give a chiral homopolymer having -49.5° specific rotation. MMI (M1 was copolymerized with styrene (ST, M2), methyl methacrylate (MMA, M2), and N-cyclohexylmaleimide (CHMI, M2) by using 2,2′-azobisisobutyronitrile (AIBN) as the radical initiator and benzene as the polymerization solvent at 50°C. The monomer reactivity ratios (r1, r2) and Alfrey-Price Q, e values were determined to be r1 = 0.28, r2 = 0.32, Q1 = 0.90, and e1 = 0.75 in MMI-ST; r1 = 0.09 and r2 = 0.51 in MMI-MMA; and r1 = 0.78 and r2 = 0.39 in MMI-CHMI. The chiroptical properties of the polymers were investigated.

Polymerization of macromonomers, 3. Monomer reactivity ratios in radical copolymerization of poly(tetrahydrofuran) macromonomers with 2‐vinylnaphthalene

AbstractMethacrylate‐terminated poly(tetrahydrofuran) (MA‐PTHF) and acrylate‐terminated poly‐(tetrahydrofuran) (A‐PTHF) macromonomers (M2) were radically copolymerized with 2‐vinylnaphthalene (2‐VN, M1). The composition of copolymers was determined by UV spectroscopy taking advantage of the very high absorption coefficient (UV) of the monomeric units of 2‐VN in copolymer. The monomer reactivity ratios r1 and r2 evaluated are as follows. MA‐PTHF: r1 =1,3 ± 0,21, ± 0,05; A‐PTHF: r1 = 2,5 ± 0,35, r2 = 0,10 ± 0,05. These reactivity ratios were compared with those in the copolymerizations of 2‐VN with the corresponding small monomers and were discussed in terms of polymer (hindering) effect and the concept of equal reactivity of growing chain.

Molecular design of block and graft copolymers by vinyl‐substituted xanthates

AbstractThe selective polymerization behavior of O‐ethyl S‐4‐vinylbenzyl xanthate (1) was investigated on the basis of polymerization kinetics in the dark and in the presence of UV‐light. S‐Benzyl O‐ethyl xanthate (2) was used as a non‐polymerizable model compound of 1 to evaluate chain transfer constants. In the homopolymerization and the copolymerization of 1 initiated with AIBN in the dark, styryl groups selectively take part in the polymerization, and xanthate groups are not responsible for it. The monomer reactivity ratios (r1 = 0,51 and rMMA = 0,41) of 1 with methyl methacrylate (MMA) are very close to those of styrene with MMA. The photolysis of 2 was investigated by 1H NMR. It was found that photodecomposition of 2 takes place at CH2S (a) and SC( = S) bonds (b) with the ratio: a/b = 1/5. The polymerization of MMA was carried out with 1 upon photoirradiation. Number‐average degrees of polymerization of the polymers obtained increase linearly with conversion. Block and graft copolymers were prepared by using these macrophotoinitiators.

Bulk Copolymerization of Acrylonitrile with Allyl Chloride and Thermal Analysis of the Products

Abstract The bulk copolymerization of acrylonitrile (M1) with allyl chloride (M2), carried out at 40 °C, was initiated by 0.05 mol% of α,α′-azobisisobutyronitrile under nitrogen. The compositions of six copolymers were in the range of allyl chloride units, 0.63–6.32 mol%. The monomer reactivity ratios r1 and r2 were calculated to be 6.04 and 0.035, respectively. Only three copolymers were soluble in N,N-dimethylformamide and their intrinsic viscosities were found to be greater than 4.5 dL g−1. The chlorine contents, although 0.42, 0.87, and 1.03 wt%, were sufficiently effective to cause a change in the behavior of the thermal degradation of polyacrylonitrile (PAN). In DTA curves measured at a rate of 5 °C min−1 under nitrogen for copolymers containing ca. 1 wt% of chlorine, a sharp exotherm due to the polymerization of cyano groups shifted to the higher-temperature side (ca. 40 °C) and the differential temperature decreased to about 1/6. Moreover, the weight loss at 350 °C decreased from 19 wt% for PAN to 13 wt%. A similar thermal-degradation behavior was also observed for acrylonitrile–α-chloroacrylonitrile (CAN) copolymers. However, there was a great difference between allyl chloride and CAN units concerning the effect on the thermal degradation of PAN. Namely, only 1.5 mol% of allyl chloride units corresponded to 10 mol% of CAN units.

Reactivities of Dialkyl Citraconates in Radical Copolymerization with Styrene

Abstract The radical copolymerization of dialkyl citraconate (DRC, R[dbnd]CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, s-C4H9, C6H11, C6H5CH2) (M1) with styrene (ST, M2) was performed at 60°C, using azobisisobutyronitrile as the initiator in tetrahydrofuran in order to clarify the polymerization behavior of DRC and the substituent effects on copolymerization. The monomer reactivity ratios r1 and r2 and the Q1 and e1 values were determined from the results obtained. It was found that the relative reactivities 1/r2 of DRC toward an attack by a polystyryl radical could be correlated not by the steric-substituent constant ES of the alkyl group in DRC, but by the polar-substituent constants σ∗ in Taft' equation: log (1/r2) = ρσ + δES. It was also observed that the e1 values are associated with Taft' σ constant. It was found that the weight-average molecular weights of the copolymers are between 8.5 × 103 and 1.4 × 104.

Reactivities of Dialkyl Dithiol Mesaconates in Radical Copolymerization with Styrene

Abstract Nine novel types of dialkyldithiol mesaconates (DRTM, M1) were synthesized and copolymerized with styrene (Ma) in tetrahydro-furan at 60 °C in order to clarify the polymerization behavior of DRTM and the substituent effects on the copolymerization. From the results obtained, the monomer reactivity ratio r1, r2 and Q1, e1 values were determined. It was found that the relative reactivities l/r2 of DRTM toward an attack by polystyryl radical were correlated only by the polar substituent constant σ∗ of the alkyl group in DRTM, but not by the steric substituent constant E, in Taft's equation: log (l/r2) = σ∗σ∗ + ΔEs. It was also observed that the Q1 and e1 values for DRTM were correlated by Taft's σ∗ constant. The number-average molecular weights of the DRTM-ST copolymer were found to be between 5.0 × 103 and 1.2 × 104.

Reactivities of N‐alkylitaconimides in radical copolymerizations with styrene or methyl methacrylate

AbstractThe radical copolymerizations of N‐alkylitaconimide (RII, R = CH3, C2H5, n‐C3H7, i‐C3H7, n‐C4H9, i‐C4H9, CH2CH2Cl, CH2C6H5) (M1) with styrene (ST) (M2) or methyl methacrylate (MMA)‐(M2) were carried out at 60°C, using azobisisobutyronitrile as an initiator in tetrahydrofuran in order to clarify the substituent effect on the copolymerizations. The monomer reactivity ratios r1, r2 and the Q1 and e1 values were determined from the results obtained. It was found that the relative reactivities 1/r2 of RII toward an attack by a poloystyryl radical could be correlated not by the steric‐substituent constant Es of the alkyl group in RII but by the polar‐substituent constant σ* in Taft's equation: log(1/r2) = ρ*σ* + δ Es. According to the above equation, the ρ* and δ values were obtained as 0.55 and 0, respectively, in the RII‐ST system, while in the RII‐MMA system, the ρ* and δ values were obtained as 0.49 and 0, respectively. It was also observed that the Q1values for RII were proportional to σ* constants and that the e1 values for RII were independent of σ* substituent constant. It was also found that the weight‐average molecular weights of the copolymers are between 8.5 × 104 and 32.5 × 104.

Effect of Solvent on the Radical Copolymerizability of Styrene with 3(2-Methyl)-6-methylpyridazinone

Abstract The radical copolymerization of styrene (St, M1) with 3(2-methyl)-6-methylpyridazinone (I, M2) has been carried out in several p-substltuted phenols at 60 and 70°C. Monomer reactivity ratios (r1) and activation parameters of copolymerization were found to be affected by phenols. The values of the activation energy (δδE‡) and entropy (δδS‡) increased with the increase of the interaction of I with the solvents. Linear relationships were observed between the [sgrave]-values of p-substituents of phenols and the values of log 1/r1 and also of δδE‡ and δδS‡. The radical copolymerization of St (M1) with 6-substituted 3(2-methyl)-pyridazinone was also carried out.

Bulk Copolymerization of Acrylonitrile with α-Chloroacrylonitrile

Abstract Copolymerization of acrylonitrile (M1) with α-chloroacrylonitrile (M2) was carried out at 60 °C using 4.3×10−2 mol% of α,α′-azobisisobutyronitrile. The four copolymers obtained were analyzed, their mole fractions of α-chloroacrylonitrile units being 0.196, 0.377, 0.532, and 0.722, and the monomer reactivity ratios r1 and r2 were found to be 0.31 and 3.25, respectively.

Solvent Effects on the Radical Copolymerizabilities of Styrene with p-Substituted N,N-Diethylcinnamamides and of p-Substituted Styrenes with Methyl Vinyl Sulfoxide

Abstract Radical copolymerizations of styrene (St) with p-substituted-N, N-diethylcinnamamides (I) and also of p-substituted styrenes (II) with methyl vinyl sulfoxide (MVSO) have been carried out in benzene, acetic acid or acetonitrile. The monomer reactivity ratios (r1) were found to be affected by the solvents, p values obtained by using the modified Hammett equation, i. e., log(1/r1) = ρσ + γ ER, were also found to be altered by the solvents. The results are discussed in terms of the solvent effect in the transition state of the propagation reaction.

Alternating polyampholytes prepared by hydrolysis of copolymer of maleic anhydride and N‐vinylsuccinimide

AbstractAlternating polyampholytes (MA‐VA) containing two acidic groups and one basic group were prepared by the copolymerization of maleic anhydride (M1) and N‐vinylsuccinimide (M2) at 60°C with AIBN as the initiator, followed by acid hydrolysis with 1N hydrochloric acid at 140°C for 24 hr. The monomer reactivity ratios r1 and r2 are 0.025 and 0.06, respectively. The structure of polymers was discussed on the basis of the data of their elementary, infrared (IR), and thermal analyses and the binding ability of heavy metal ion. Polyampholytes were soluble in strong acidic and basic media but were precipitated in the pH range 3–4. An isoelectric point at pH 3 was determined by potentiometric titration and the turbidimetric method. By thermal treatment above 205°C the polyampholyte turned quantitatively into a cyclized lactam. This suggests that the polyampholyte MA–VA has an intramolecular hydrogen bond between the amino and γ‐carboxyl groups. The binding of Cu2+ and Hg2+ by the polyelectrolyte was evaluated by equilibrium dialysis.

Reactivity ratios of ionizing monomers in aqueous solution. Copolymerization of acrylic and methacrylic acids with acrylamide

AbstractThe copolymerization behaviour of the systems (a) acrylic acid (AA)‐acrylamide (AM) and (b) methacrylic acid (MA)‐acrylamide was studied in aqueous solution at 30°C as a function of pH. The copolymerization was carried out to high conversion (>10%) and the monomer reactivity ratios r1 for (AA or MA) and r2 (for AM) were computed using the Mayo‐Lewis integrated equation. For the system (a), r1 reached its maximum value of 0,92 at pH 2, and its minimum of 0,33 at pH 6, thereafter increasing again. No systematic variation was found for r2. In system (b), r1 decreased sharply from a maximum of 2,8 at pH 4 to 0,19 at pH 6, then increasing to 0,39 as the pH was raised to 10. The r2 value showed a gradual increase from 0,2 at pH 4 to 0,57 at pH 9. Addition of NaCl (conc.: 1 mol/l) partially restored the value of r1 for both AA and MA to those at low pH. The variation of r1 of AA and MA nearly parallelled the homopolymerization rates of the respective monomers, with respect to pH. These variations were traced to the electrostatic repulsive interactions between the reactive species—ionized monomer and ionized polymeric radical—and hydrophobic interactions. Certain discrepancies in the trends of r1 and r2 were also noted.

Effect of pH on radical polymerization of butadiene 1‐carboxylic acid in aqueous solutions

AbstractRadical polymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) was carried out in aqueous solutions at 50°C with ammonium persulfate (APS) as an initiator. Kinetic studies led to the rate equation, Rp = k[APS]1/2 [Bu‐1‐Acid]1 at pH 6.8. The overall activation energy for the polymerization was 16.0 kcal/mole. The polymerization rate Rp of Bu‐1‐Acid decreased with an increase of pH in the range 2.4–6.8 and increased with an increase of pH in the range 6.8–8.4. Moreover, in the pH range 8.4–13, the rate of polymerization was not affected by the pH of the system. In copolymerization with acrylonitrile, the trends of changes in the monomer reactivity ratios r1, r2 and Q‐e values caused by changes in pH were similar to trends found in homopolymerization described above. In addition, it was observed that the resultant polymer was extended in alkaline solution and contracted in acidic solution.

Radiation copolymerization of vinylene carbonate with isobutyl vinyl ether

AbstractThe radiation‐induced copolymerization of vinylene carbonate (M1) with isobutyl vinyl ether (M2) has been investigated over the temperature range of 40–80°C. The monomer reactivity ratios r1 and r2 were determined to be 0.118 and 0.148, respectively, and an activation energy of 7.6 kcal/mole (31.8 kJ/mole) was calculated for the copolymerization process.

Effect of solvent in radical polymerization of butadiene 1‐carboxylic acid

AbstractThe radical polymerization and copolymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) were studied in a variety of the electron‐donor solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone (MEK), acetonitrile (ACN), and benzene (BZ) using AIBN as an initiator at 50°C. Under these conditions, the polymerization rate of Bu‐1‐Acid increased in the order, DMF < THF < MEK < ACN < BZ in the various solvents. In copolymerization with styrene [M2] and acrylonitrile [M2], the monomer reactivity ratio r1 increased and r2 decreased in the same order. Moreover, it was found that Alfrey‐Price Q‐e value of Bu‐1‐Acid increased depending on solvent in the order DMF < THF < MEK < ACN < BZ. These variations were correlated to the electron‐donating power (Δvcm−) of the solvents used and are discussed on the basis of the solvation of Bu‐1‐Acid into the solvent. Also, it was found that the microstructures of these polymers were always trans‐1,4 and did not change with the solvent used.

Radical polymerization of butadiene‐1‐carboxylic acid

AbstractThe homopolymerization and copolymerization of butadiene‐1‐carboxylic acid (Bu‐1‐Acid) (M1) were studied in tetrahydrofuran at 50°C with azobisisobutyronitrile as an initiator. The initial rate of polymerization was proportional to [AIBN]1/2 and [Bu‐1‐Acid]1. The overall activation energy for the polymerization was 22.87 kcal/mole. For copolymerization with styrene (M2) and acrylonitrile (M2), the monomer reactivity ratios r1, r2 were determined by the Fineman‐Ross method, as follows; r1 = 5.55, r2 = 0.08 (M2 = styrene); r1 = 11.0, r2 = 0.03 (M2 = acrylonitrile). Alfrey‐Price Q‐e values calculated from these values were 6.0 and +0.11, respectively. The Bu‐1‐Acid unit in the copolymer as well as the homopolymer was found from infrared and NMR spectral analyses to be composed of a trans‐1,4 bond. The hydrogen‐transfer polymerization of Bu‐1‐Acid leading to polyester was attempted with triphenylphosphine as initiator, but did not occur.

Preparation of poly[N‐(3‐acryloylaminopropyl)carbazole] and its charge transfer complex with 2,4,7‐trinitrofluorenone

AbstractA new carbazole polymer, poly{1‐[3‐(9‐carbazolyl)propylaminocarbonyl]ethylene} {poly[N‐(3‐acryloylaminopropyl)carbazole]} (6) was prepared by radical polymerization of N‐(3‐acryloylaminopropyl)carbazole (5). Copolymerization of 5 (M1) with styrene (M2) provided the monomer reactivity ratios r1 = 0,13±0,08 and r2 = 3,47±0,12. The Q‐e values of 5 were calculated as Q1 = 0,18 and e1 = +0,10. Fluorescence spectra of 6 and N‐(3‐isobutyrylaminopropyl)carbazole (2), prepared as a monomer model compound, were nearly identical, indicating the absence of intramolecular excimer formation for 6. The stability constants (K) of the charge transfer complexes of 6 and 2 with 2,4,7‐trinitrofluorenone (TNF) were determined in 1,2‐dichloroethane at 20°C under the conditions of both [6] or [2]≫[TNF] and [6] or [2]≪[TNF]. The values of K were 4,9 and 5,2dm3 mol−1 for 2 when [2]≫[TNF] and [2]≪[TNF], respectively, and 16dm3 mol−1 for 6 when [6]≫[TNF]. The polymer 6 precipitated, however, when [6]≪[TNF]. As a reference, charge transfer complex formation of poly[1‐(9‐carbazolyl)‐ethylene] [poly(N‐vinylcarbazole)] [1] with TNF was studied under the same conditions. The values of K for 1 were identical when [1]≫[TNF] and [TNF]. These results were explained by assuming a sandwich‐type charge transfer complex for 6, but not for 1. The space between the carbazolyl groups in 1 would be too small to accomodate a TNF molecule between the chromophores.