Monomer Reactivity Ratios R1 Research Articles

Thermal behavior of pentachlorophenyl methacrylate-acrylonitrile copolymers

Acrylonitrile was copolymerized with pentachlorophenyl methacrylate (PCPMA)in dimethyl formamide using azobisisobutyronitrile as initiator. The composition of the copolymers was determined by nitrogen analysis and the monomer reactivity ratios (r1 and r2) were calculated. Both the homopolymer and the copolymers were characterized by a variety of spectral and thermal methods. Thermogravimetry and differential thermal analysis data showed that the comonomer (PCPMA) initiates the nitrile oligomerization reaction in the copolymer upon heating. A mechanism for the initiation of (PCPMA) units in the nitrile copolymers was also proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 296–302, 2004

Copolymerization of dodecyl‐4‐vinyl benzoate and dodecyl acrylate by conventional, atom transfer, and nitroxide‐mediated free‐radical polymerization

Abstractn‐Dodecyl acrylate (DA) and dodecyl‐4‐vinyl benzoate (DVB) were copolymerized by conventional free‐radical polymerization (CFRP); atom transfer radical polymerization (ATRP), and nitroxide‐mediated living free‐radical polymerization (NMLFRP) with benzoyl peroxide, 1‐phenyl ethyl chloride/cuprous chloride/2,2′‐bipyridine, and benzoyl peroxide/2,2,6,6‐tetramethylpiperidinyl‐1‐oxy initiator systems, respectively. In CFRP and NMLFRP, toluene and xylene were used as solvents, whereas ATRP was performed in bulk. Mayo–Lewis, Kelen–Tüdös, and Fineman–Ross methods were used for the determination of the monomer reactivity ratios (r1 and r2). They all gave nearly the same values of r1 and r2. The reactivity ratios of the two monomers in CFRP, ATRP, and NMLFRP were 0.17 ≤ r1 ≤ 0.4 (DA) and 1.0 ≤ r2 ≤ 1.24 (DVB). The side‐chain crystallinity of the copolymers decreased with an increasing DVB molar fraction. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1818–1830, 2002

Free‐radical copolymerization of 3‐phthalimido‐2‐hydroxypropyl methacrylate with styrene: The determination of monomer reactivity ratios and thermal analysis studies

AbstractFree‐radical copolymerizations of styrene and phthalimido‐2‐hydroxypropyl methacrylate (PHPMA) were carried out at 60 °C in a 1,4‐dioxane solution in the presence of 2,2′‐azobisisobutyronitrile at low conversions (<15%). The copolymer compositions were established by elemental analysis. The monomer reactivity ratios r1 (PHPMA) and r2 (styrene) were determined with the linearized copolymerization equations of the Kelen–Tüdös and inverted Fineman–Ross methods and with the nonlinear relationship of the Mayo–Lewis method to be r1 = 1.41 and r2 = 0.24, r1 = 1.52 and r2 = 0.26, and r1 = 1.15 and r2 = 0.16, respectively. The monomer reactivity ratios and glass‐transition temperatures of the copolymers as functions of the copolymer composition are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 650–658, 2002; DOI 10.1002/pola.10140

FURTHER STUDY OF ALLYL ETHERS AND RELATED COMPOUNDS AS TRANSFER AGENTS IN RADICAL POLYMERIZATIONS

Allyl glycidyl ether (AGE), allyl 1,1,2,3,3,3-hexafluoropropyl ether (AFE), allyl 2-naphthyl ether (ANE), 2-vinyl-1,3-dioxolane (2VD) and allyl alcohol (AA) have been examined as transfer agents in the radical polymerization of methyl methacrylate (MMA) at 60°C; the transfer constants are 1.1 × 10−3, 0.1 × 10−3, 0.2 × 10−3, 1.1 × 10−3 and 0.6 × 10−3, respectively. AFE and AA barely affect the rate of polymerization: AGE, ANE, and 2VD act as weak retarders. There is no direct correlation between effectiveness as a transfer agent and the extent of retardation for these additives. For copolymerization with MMA (monomer-1), the monomer reactivity ratios r1 are 42 ± 5 and 32 ± 5 for AGE and ANE, respectively; for both cases, r2 is very close to zero; 2VD engages in copolymerization with MMA to a negligible extent. Experiments involving styrene or acrylonitrile gave results consistent with those obtained using MMA.

Syntheses and Polymerizations of Novel Chiral Methacrylates Bearing Urethane Bonds and N,N-Dibenzylamino Groups

Four new chiral methacrylates bearing urethane bonds and N,N-dibenzylamino groups (RMOC) were synthesized from 2-methacryloyloxyethyl isocyanate (MOI) and four chiral alcohol derivatives of α-amino acids, L-valine, L-leucine, D-phenylglycine, and L-phenylalanine. Radical polymerizations of RMOC were performed under various conditions to obtain the corresponding poly(RMOC) with number average molecular weights (M̅n) of 2.4×104—6.4×104. Poly(RMOC) has hydrogen bonds based on urethane segments in solvent and exhibited negative (levo) rotation. Specific optical rotations of poly(RMOC) were slightly influenced by solvent and temperature. Radical copolymerizations of RMOC with styrene (ST) and methyl methacrylate (MMA) were performed with AIBN in toluene at 60°C. Monomer reactivity ratios (r1, r2) and Alfrey-Price Q-e were determined. Chiroptical properties of the copolymers were scarcely affected by co-units of ST and MMA. Chiral stationary phases (CSPs) for high performance liquid chromatography (HPLC) were prepared from poly(RMOC) and silica gel and optical resolution ability was investigated. CSPs resolved some racemic compounds (1—5) using methanol/water as mobile phase.

VINYLTRIMETHYLSILANE-CO-METHYLMETHACRYLATE COPOLYMERS. SYNTHESIS AND REACTIVITY RATIOS

In order to obtain information about the copolymerization process of vinyltrimethyl silane with comonomers of different chemical structure, copolymers containing vinyltrimethylsilane and methyl methacrylate at different compositions were synthesized and characterized. Comparison of the reactivity ratios of the resulting copolymers with those containing N-vinyl-2-pyrro-lidone and 2-vinylpyridine previously reported and other related comonomers with different chemical structure allows us to establish some reactivity structure relationship and a generalization for these systems. The monomer reactivity ratios r1 and r2 (MRR) were estimated by using the classical linear fitting procedures and also through a computer program based on a nonlinear minimization algorithm, starting from the r1 and r2 values obtained by the former procedures.

Functional Copolymers of N-(4-Formyl-Phenoxy-4′-Carbonylphenyl) Maleimide with Styrene

A new reactive N-substituted maleimide monomer containing an aldehyde function, N-(4-formyl-phenoxy-4′-carbonylphenyl) maleimide (MI-CHO), was synthesized. The radical copolymerization of MI-CHO with styrene was performed at 60 °C in the presence of 2,2′-azoisobutyronitrile as an initiator in dimethylsulfoxide. The copolymerization of MI-CHO with styrene yielded the ‘nearly equimolar’ alternating copolymers for the mole fractions of MI-CHO in the feed ranging from 0.2 to 0.7. The monomer reactivity ratios ( r1, r2) in the polymerization of MI-CHO ( M1) with styrene ( M2) and the Alfrey–Price Q1 and e1 parameters were determined. The thermal properties of the copolymers were investigated by using thermogravimetric analysis and differential scanning calorimetry.

N-1-ALKYLITACONAMIC ACIDS-CO-STYRENE COPOLYMERS. 1. SYNTHESIS, CHARACTERIZATION AND MONOMER REACTIVITY RATIOS

Copolymers containing N-1-ethylitaconamic acid, N-1-propyl-itaconamic acid, N-1-butylitaconamic acid, N-1-hexylitaconamic acid, N-1-octylitaconamic acid and N-1-decylitaconamic acid with styrene of different comonomer compositions were synthesized and characterized. Copolymer composition was determined by elemental analysis following the nitrogen content in the resulting copolymers. Monomer reactivity ratios r1 and r2 of the different copolymers were estimated using straight line intersection procedures such as Fineman-Ross (F-R) and Kelen-Tüdos (K-T) and by a nonlinear one, according to the reactivity ratios error-in-variables model (RREVM). Good agreement between the different procedures for r1 and r2 determination was found. Differences in the reactivity of N-1-alkylitaconamic acids (NAIA) relative to styrene were found i.e., ethyl and propyl derivative are less reactive with itself than butyl, hexyl, octyl, and decyl derivatives with itself. Copolymers with some tendency toward small block formation are found.

Free-radical copolymerization of vinyl esters using fluoroalcohols as solvents: The solvent effect on the monomer reactivity ratio

Free-radical copolymerizations of vinyl acetate (VAc = M1) and other vinyl esters (= M2) including vinyl pivalate (VPi), vinyl 2,2-bis(trifluoromethyl)propionate (VF6Pi), and vinyl benzoate (VBz) with fluoroalcohols and tetrahydrofuran (THF) as the solvents were investigated. The fluoroalcohols affected not only the stereochemistry but also the polymerization rate. The polymerization rate was higher in the fluoroalcohols than in THF. The accelerating effect of the fluoroalcohols on the polymerization was probably due to the interaction of the solvents with the ester side groups of the monomers and growing radical species. The difference in the monomer reactivity ratios (r1, r2) in THF and 2,2,2-trifluoroethanol was relatively small for all reaction conditions and for the monomers tested in this work, whereas r1 increased in the VAc-VF6Pi copolymerization and r2 decreased in the VAc-VPi copolymerization when perfluoro-tert-butyl alcohol was used as the solvent. These results were ascribed to steric and monomer-activating effects due to the hydrogen bonding between the monomers and solvents. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 220–228, 2000

The kinetics of radical copolymerization of acrylonitrile and methylacrylate with tricaprylylmethylammonium chloride as a phase-transfer catalyst

The phase-transfer radical copolymerization of acrylonitrile (AN) and methylacrylate (MA) with tricaprylylmethylammonium chloride was investigated in Na2S2O8 aqueous-organic two-phase system at 25°C and under nitrogen atmosphere. The rate of copolymerization was expressed as the combined terms of quaternary ammonium ion and peroxydisulfate ion in the aqueous phase rather than the fed concentrations of catalyst and Na2S2O8. The observed initial rate of copolymerization was used to analyze the copolymerization mechanism with a cyclic phase-transfer initiation step in the heterogeneous liquid–liquid system. The monomer reactivity ratio r1 and r2 obtained from the analysis of copolymerization mechanism were 1.584 and 0.856, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3504–3512, 1999

Transformation of copolymerization mechanism ofN-phenyl maleimide and ethyl phenylacrylate in the mixture of dioxane and pyridine

The copolymerization of N-phenylmaleimide (NPMI) with ethyl phenylacrylate (EPA) in a mixture of dioxane (DIO) and pyridine (Py) was investigated. The apparent monomer reactivity ratio r1 (NPMI) = 0.07 ± 0.01 and r2 (EPA) = 0.09 ± 0.02 in DIO was turned to r1 (NPMI) = 3.67 ± 0.07 and r2 (EPA) = 0 ± 0.03 in Py. The copolymerization of NPMI and EPA with the fixed feed ratio (mol/mol 1 : 1) in different volume ratio of DIO/Py showed that the copolymer composition might be varied in a wide range from the 93.5% of NPMI contents in copolymer to 48.7%. When the volume fraction of Py in the mixture of DIO and Py was 10%, the following two kinds of copolymers were formed: a copolymer in which the content of NPMI increased with the Py and the copolymerization also could be inhibited by hydroquinone and a copolymer with low molecular weight almost completely composed of homopolymer of NPMI and is not affected by radical inhibitor as hydroquinone. The transformation of the copolymerization mechanism from the radical to anionic, which was dependent on the volume ratio of DIO and Py, was suggested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2755–2761, 1999

Reactivity in the Radical Copolymerization of Poly(2-oxazoline) Macromonomers with Methacrylate Monomers

The radical copolymerization of vinylbenzyl-terminated poly(2-methyl-2-oxazoline) macromonomers (1 Me-n; n (degree of polymerization) = 3, 15, 28, 31) (M1) with vinyl monomers (M2), i.e., methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) was performed using 2, 2′-azobis(isobutyronitrile) (AIBN) as an initiator at 60°C in ethanol (EtOH). CD3OD, or CD3CN. Monomer reactivity ratios r1 and r2 were evaluated based on the terminal model. Copolymerization of 1 Me-3 with MMA gave reactivity ratios as r1=1.86±1.15 and r2=0.07±0.03 in EtOH, and r1=1.25±0.10 and r2=0.18±0.05 in CD3OD, exhibiting remarkably higher reactivity of the Me-3 compared with the comonomers and corresponding small monomer, styrene. In CD3CN, however, copolymerization of 1 Me-3 with MMA gave r1=0.41±0.10 and r2=0.66±0.10, showing rather lower reactivity of the macromonomer compared with MMA. With HEMA, 1 Me-3 showed high reactivity in EtOH, i.e., r1=1.44±0.10, r2=0.04±0.02. The reactivity of HEMA against the macromonomers was found higher than that of MMA, possibly due to affinity to aprotic poly(2-methyl-2-oxazoline) graft chains on growing species. The high reactivity of 1 Me-n in EtOH and CD3OD would be due to the formation of a micelle-like state. The reactivity of macromonomers decreased generally with chain length (n).

Synthesis of 7,8-bis(benzyloxycarbonyl)-7,8-dicyanoquinodimethane, polymerization, and some properties of its polymer

7,8-Bis(benzyloxycarbonyl)-7,8-dicyanoquinodimethane (1d) was prepared successfully as isolable crystals at room temperature and determined to have an anti-form by 1H-NMR spectroscopy. When 1d was dissolved in basic polar solvents such as acetonitrile, acetone, tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide, spontaneous polymerization took place to give polymers with Mn of 6 x 103 to 9.7 x 105. 1d is homopolymerizable with 2,2'-azobis(isobutyronitrile) (AIBN) as a radical initiator, triethylamine, proton sponge, and triphenylphosphine, but not with boron trifluoride diethyl etherate as a cationic initiator. 1d copolymerized with styrene (St) in the presence of AIBN in chloroform to obtain the monomer reactivity ratios r1 (1d) = 3.1 ± 0.5 and r2(St) = 0.030 ± 0.01 at 60 ° C, and Q and e values of 9.3 and + 0.73, respectively, indicating that 1d is highly conjugative and electron-accepting. The thermal behavior and photodegaradation for poly(1d) were investigated in comparison with the polymer of 7,8-bis(butoxycarbonyl)-7,8-dicyanoquinodimethane (1c).

Alternating Copolymerization of Maleimide and Ethyl Atropate Without Initiator

ABSTRACT The copolymerization of maleimide(MI)(M1) and ethyl atropate (EAP)(M2) was carried out by self-initiation at 60°C, in which M2(Q=0.43, e=0.92) and M1 (Q=0.44, e=1.35) constituted a pair of electron donor and acceptor monomers on Price-Alfrey equation. A high alternating tendency was observed, the monomer reactivity ratios r1 =0.048±0.016 and r2=0.12±0.012 were calculated by a nonlinear least-squares procedure. The spontaneous alternative copolymerization is considered to be carried out by the induced radicals produced via a contact-type charge transfer complex between M1 and M2, which was confirmed by UV spectra. Thermogravimetric analysis (TGA) shows that the resulting copolymers have high thermal stability.

Polymerization ofmeta-naphthoquinone methide: 3,4-benzo-6-methylenebicyclo [3.1.0] hex-3-ene-2-one

Polymerization behavior of meta-naphthoquinone methide, 3,4-benzo-6-methylenebicyclo[3.1.0]hex-3-ene-2-one (1), was studied. Radical initiator 2,2′-azobis(isobutyronitrile) (AIBN) induced polymerization of 1, but ionic initiators potassium tert-butoxide, butyllithium, and boron trifluoride etherate did not. Polymerization of 1 proceeded via ring-opening and aromatization to give a polymer with head-to-tail monomer unit placement. Compound 1 copolymerized with methyl methacrylate (MMA) in the presence of AIBN to obtain the monomer reactivity ratios r1 (1) = 0.28 ± 0.07 and r2(MMA) = 0.39 ± 0.02 at 60°C and Q and e values of Q = 1.04 and e = −1.03, indicating that 1 is a conjugative and electron-donating monomer. Ring-opening and aromatization of 1 also took place in the copolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 741–746, 1997

Propagation and termination processes in free radical copolymerization

AbstractThe propagation and termination processes in free radical copolymerization were discussed on the basis of current experimental data. It was shown that the penultimate unit effect (PUE) in propagation is very general, affecting not only the absolute values of the rate constant but also the monomer reactivity ratios r1 and r2. The analysis suggests that the alternating index r1r2 originates in the PUE. An adequate description of the termination process also requires a penultimate model, which leads to a general, yet simple two‐parameter rate‐of‐copolymerization equation with PUEs in both propagation and termination.

Synthesis and polymerization of N-[4-(cholesteroxycarbonyl)phenyl]itaconimide

A new type of optically active N-[4-(cholesteroxy-carbonyl)phenyl]itaconimide (ChPII) was synthesized from itaconic anhydride, aminobenzoic acid and cholesterol. Radical homopolymerizations of ChPII were performed in several solvents at 60°C to give optically active polymers having [α]D = 1.7 to [α]D = −6.2°. Anionic homopolymerizations of ChPII were also carried out. Radical copolymerizations of ChPII(M1) were performed with styrene (ST, M2), and methyl methacrylate (MMA, M2) in toluene at 60°C. From the reslts, the monomer reactivity ratios (r1, r2) and the Alfrey-Price Q, e values were determined as follows: r1 = 0.26, r2 = 0.10, Q1 = 2.17, e1 = 1.11 for the ChPII-ST system; r1 = 0.187, r2 = 0.37, Q1 = 2.55, e1 = 1.01 for the ChPII-MMA system. ChPII polymer and copolymers were still optically active after hydrolysis, which suggests that asymmetric induction into the polymer main chain took place. Chiroptical properties of the polymers and copolymers were investigated.

Synthesis and polymerization of 7,7-bis(alkoxycarbonyl)-1,4-benzoquinone methides

7,7-Bis(methoxycarbonyl)-, 7,7-bis(ethoxycarbonyl)-, and 7,7-bis(isopropoxycarbonyl)-1,4-benzoquinone methides (4a, 4b, and 4c) were successfully prepared as pure, isolable yellow-orange needles. The values of the first reduction potential for 4a, 4b, and 4c were measured in dichloromethane containing tetrabutylammonium perchlorate by cyclic voltammetry to be −0.54, −0.55, and −0.55 V, respectively, indicating that the alkyl groups do not significantly affect their electron-accepting properties. An anionic initiator butyllithium induced the homopolymerizations of 4a–c at 0°C, but a cationic initiator boron trifluoride etherate did not of 4a–c at 0°C. Compounds 4a and 4b homopolymerized with a radical initiator 2,2′-azobis(isobutyronitrile) (AIBN), but 4c did not, probably due to a larger steric hindrance effect of the isopropyl group compared with methyl and ethyl groups. Homopolymerizable compound 4a copolymerized with styrene in benzene in the presence of AIBN in a random fashion to give the monomer reactivity ratios r1 (4a) = 2.40 ± 0.40 and r2 (styrene) = 0.01 ± 0.02 at 60°C and the Q and e values of 4a were 21.2 and +1.13, respectively, indicating that 4a is a highly conjugative and electron-accepting monomer, while the nonhomopolymerizable compound 4c copolymerized with styrene in a perfectly alternating fashion in benzene in the presence of AIBN at 60°C. No copolymerizations of 4a or 4c with 7,7,8,8-tetracyanoquinodimethane took place in dichloromethane in the presence of AIBN at 60°C. © 1996 John Wiley & Sons, Inc.

Design and Development of Isocyanatoacrylates as Dental Adhesives

During the last 12 years, significant progress has been made in the development of dental adhesive systems. Some of the more promising systems are based on multifunctional structures that contain polymerizable vinyl double bonds and reactive isocyanate groups. The utility of compounds with such structures as adhesives arises in part because their isocyanate functionality is available for reaction independently, without compromising the reactivity of the vinyl groups. The hypotheses tested in this investigation were: (1) that the monomer reactivity ratios (r1, r2) for the free-radical-initiated copolymerization of ethyl alpha-isocyanatoacrylate (alpha-EIA) and 2-isocyanatoethyl methacrylate (IEM) with selected vinyl monomers can be determined; (2) that these reactivity ratios can be used to establish Q (reactivity) and e (polarity) values for alpha-EIA and IEM; and (3) that these reactivity parameters can be useful in designing copolymers with controlled compositions for dental adhesive applications. The free-radical copolymerization characteristics of alpha-EIA and IEM were studied. The isocyanate monomers were copolymerized at seven comonomer ratios with n-butyl acrylate (NBA), methyl methacrylate (MMA), and styrene (STY). Reactivity ratios, r1 and r2, were calculated for each of the copolymer systems, giving:IEM (r1) = 0.38 and STY (r2) = 0.44; IEM (r1) = 1.19 and MMA (r2) = 0.84; IEM (r1) = 2.50 and NBA (r2) = 0.40; alpha-EIA (r1) = 2.20 and STY (r2) = 0.06; alpha-EIA (r1) = 7.00 and MMA (r2) = 0.10; and alpha-EIA (r1) = 23.50 and NBA (r2) = 0.04. The Q (reactivity) and e (polarity) values for IEM and alpha-EIA were calculated from r1 and r2 with use of the Alfrey-Price equations, giving, for IEM, Q = 0.89 and e = 0.60, and, for alpha-EIA, Q = 7.64 and e = 0.74. These reactivity parameters are useful for tailoring copolymers with controlled compositions and properties. Based on these calculated reactivity parameters, several copolymers of IEM [for example, IEM/2-hydroxyethyl methacrylate (HEMA)] are currently being prepared and evaluated as adhesives.

Radical polymerization and antibacterial activity of copolymers based on N-1-adamantylmaleimide

New copolymers were prepared by radical polymerization starting from N-1-adamantylmaleimide (AMI) and styrene (ST). The copolymerization of AMI with ST proceeded easily to give medium molecular weight of copolymers $$\left( {\overline M _n > {\text{10}}^{\text{4}} } \right)$$ in high yield. The poly(AMI-co-ST)s had high Tg (205–236 °C) and good thermal stability. Moreover, the poly(AMI-co-ST)s exhibited activity against the staphlococcus aureus ATCC 25923. The monomer reactivity ratios(r1,r2) in the copolymerizations of AMI with ST, and Alfrey-Price Q, e values for AMI were determined.